Publications

All publications by the Senge Group

Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing

Konrad, N.; Horetski, M.; Sihtmäe, M.; Truong, K.-N.; Osadchuk, I.; Burankova, T.; Kielmann, M.; Adamson, J.; Kahru, A.; Rissanen, K.; Senge, M.O.; Borovkov, V.; Aav, R.; Kananovich, D. Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing. Chemosensors 2021, 9, 278

Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto′s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto′s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2—7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their supramolecular binding to a series of zinc porphyrins was studied with UV-Vis and circular dichroism (CD) spectroscopy, computational analysis and single crystal X-ray diffraction. The association constant values generally increased with the increasing electron-withdrawing properties of the porphyrins and electron-donating ability of the thioureas, a result of the predominant ZnN cation—dipole (Lewis acid—base) interaction. The binding event induced a CD signal in the Soret band region of the porphyrin hosts—a crucial property for chirality sensing of Takemoto-type thioureas

https://dx.doi.org/10.3390/chemosensors9100278

Porphyrinoids for Photodynamic Therapy

Melissari, Z.; Williams, R. M.; Senge, M. O. Porphyrinoids for Photodynamic Therapy. In Applications of Porphyrinoids as Functional Materials; (H. Lang, T. Rüffer (eds.)). The Royal Society of Chemistry, 2021; 252—291

Heliotherapy (Greek etymology: ήΛΙΟ+ ΘΕΡΑΠΕίΑ= sun+ therapy) is the alleviating and therapeutic effect of natural sunlight that can be used to treat skin or muscle disorders. Phototherapy (PT)(Greek etymology: ΦώΤΟ+ ΘΕΡΑΠΕίΑ= light+ therapy) dates back thousands of years when Egyptians, Indians, Chinese, Romans, and Greeks were instinctively utilizing sunlight to treat several diseases, including vitiligo, tuberculosis, and psoriasis. 1 Many advances related to the clinical use and safety of PT have been made in the last 50 years, notably in the area of photodynamic therapy (PDT). PDT is an example of PT where light is used to alleviate and treat malignant diseases such as cancer and infections. In PDT, the so-called photosensitizer ...

https://dx.doi.org/10.1039/9781839164149-00252

Synthesis and Properties of BODIPY Appended Tetraphenylethylene Scaffolds as Photoactive Arrays

Sample, H. C.; Emandi, G.; Twamley, B.; Grover, N.; Khurana, B.; Sol, V.; Senge, M. O. Synthesis and Properties of BODIPY Appended Tetraphenylethylene Scaffolds as Photoactive Arrays. European Journal of Organic Chemistry 2021, 2021, 4136—4143.

Tetraphenylethylene (TPE) and its derivatives exhibit excellent aggregation-induced emission (AIE) properties. The TPE unit is easily accessible, and many functional groups can be introduced in a facile manner to yield effective luminescent materials in both solution and the solid-state. It is because of this, several TPE-based compounds have been developed and applied in many areas, such as OLEDs and chemical sensors. Boron dipyrromethenes (BODIPYs) are a class of pyrrolic fluorophore of great interest with myriad application in both material science and biomedical applications. Through the combination of Pd-catalyzed cross-coupling reactions and traditional dipyrromethene chemistry, we present the syntheses of novel tetra-BODIPY-appended TPE derivatives with different distances between the TPE and BODIPY cores. The TPE-BODIPY arrays 6 and 9 show vastly differing AIE properties in THF/H2O systems, with 9 exhibiting dual-AIE, along with both conjugates being found to produce singlet oxygen (1O2). We presume the synthesized BODIPY-appended TPE scaffolds to be utilized for potential applications in the fields of light-emitting systems and theranostics.

https://dx.doi.org/10.1002/ejoc.202100629

Development of Antimicrobial Laser-Induced Photodynamic Therapy Based on Ethylcellulose/Chitosan Nanocomposite with 5,10,15,20-Tetrakis(m-Hydroxyphenyl)porphyrin

Hasanin, M.S.; Abdelraof, M.; Fikry, M.; Shaker, Y.M.; Sweed, A.M.K.; Senge, M.O. Development of Antimicrobial Laser-Induced Photodynamic Therapy Based on Ethylcellulose/Chitosan Nanocomposite with 5,10,15,20-Tetrakis(m-Hydroxyphenyl)porphyrin. Molecules 2021, 26, 3551.

The development of new antimicrobial strategies that act more efficiently than traditional antibiotics is becoming a necessity to combat multidrug-resistant pathogens. Here we report the efficacy of laser-light-irradiated 5, 10, 15, 20-tetrakis (m-hydroxyphenyl) porphyrin (m THPP) loaded onto an ethylcellulose (EC)/chitosan (Chs) nanocomposite in eradicating multi-drug resistant Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. Surface loading of the ethylcelllose/chitosan composite with m THPP was carried out and the resulting nanocomposite was fully characterized. The results indicate that the prepared nanocomposite incorporates m THPP inside, and that the composite acquired an overall positive charge. The incorporation of m THPP into the nanocomposite enhanced the photo-and thermal stability. Different laser wavelengths (458; 476; 488; 515; 635 nm), powers (5—70 mW), and exposure times (15—45 min) were investigated in the antimicrobial photodynamic therapy (aPDT) experiments, with the best inhibition observed using 635 nm with the m THPP EC/Chs nanocomposite for C. albicans (59±0.21%), P. aeruginosa (71.7±1.72%), and S. aureus (74.2±1.26%) with illumination of only 15 min. Utilization of higher doses (70 mW) for longer periods achieved more eradication of microbial growth.

https://dx.doi.org/10.3390/molecules26123551

Conformational Design of Enzyme-like Porphyrin Binding Pockets for Catalysis and Sensing

Senge, M. O. Conformational Design of Enzyme-like Porphyrin Binding Pockets for Catalysis and Sensing. ECS Meeting Abstracts 2021, 16, 783

Porphyrins have long been recognized as sensors for various analytes. However, this involves mostly metalloporphyrins and there are still limitations with regard to discrimination and sensitivity. Here we illustrate that metal-free metal-free (′free base′) porphyrins can be re-engineered via conformational design to make the core N-H units accessible for interaction with substrates or analytes. This allows to utilize metal-free porphyrin free bases as organocatalysts. Highly conjugated porphyrin macrocyclic systems offer spectrophotometric sensitivity towards geometrical and/or electronic changes and thus, utilizing the porphyrin core for selective detection of substrates in solution offers significant potential for applications. As a proof-of-concept we describe how a combination of macrocycle distortion in conjunction with suitable functional groups in the porphyrin periphery allowed the design of the binding pocket in an …

https://dx.doi.org/-

Ligand-Targeted Delivery of Photosensitizers for Cancer Treatment

Gierlich, P., Mata, A.I., Donohoe, C., Brito, R.M.M., Senge, M.O., Gomes-da-Silva, L.C., Ligand-Targeted Delivery of Photosensitizers for Cancer Treatment. Molecules 2020, 25(22), 5317.

Photodynamic therapy (PDT) is a promising cancer treatment which involves a photosensitizer (PS), light at a specific wavelength for PS activation and oxygen, which combine to elicit cell death. While the illumination required to activate a PS imparts a certain amount of selectivity to PDT treatments, poor tumor accumulation and cell internalization are still inherent properties of most intravenously administered PSs. As a result, common consequences of PDT include skin photosensitivity. To overcome the mentioned issues, PSs may be tailored to specifically target overexpressed biomarkers of tumors. This active targeting can be achieved by direct conjugation of the PS to a ligand with enhanced affinity for a target overexpressed on cancer cells and/or other cells of the tumor microenvironment. Alternatively, PSs may be incorporated into ligand-targeted nanocarriers, which may also encompass multi-functionalities, including diagnosis and therapy. In this review, we highlight the major advances in active targeting of PSs, either by means of ligand-derived bioconjugates or by exploiting ligand-targeting nanocarriers.

https://dx.doi.org/10.3390/molecules25225317

2D Porphyrinic Metal-Organic Frameworks Featuring Rod-Shaped Secondary Building Units

Elliott, R., Ryan, A.A., Aggarwal, A., Zhu, N., Steuber, F.W., Senge, M.O., Schmitt, W., 2D Porphyrinic Metal-Organic Frameworks Featuring Rod-Shaped Secondary Building Units. Molecules 2021, 26, 2955.

Metal-organic frameworks (MOFs) encompass a rapidly expanding class of materials with diverse potential applications including gas storage, molecular separation, sensing and catalysis. So-called ′rod MOFs′, which comprise infinitely extended 1D secondary building units (SBUs), represent an underexplored subclass of MOF. Further, porphyrins are considered privileged ligands for MOF synthesis due to their tunable redox and photophysical properties. In this study, the CuII complex of 5,15-bis(4-carboxyphenyl)-10,20-diphenylporphyrin (H2L-CuII, where H2 refers to the ligand′s carboxyl H atoms) is used to prepare two new 2D porphyrinic rod MOFs PROD-1 and PROD-2. Single-crystal X-ray analysis reveals that these frameworks feature 1D MnII- or CoII-based rod-like SBUs that are coordinated by labile solvent molecules and photoactive porphyrin moieties. Both materials were characterised using infrared (IR) spectroscopy, powder X-ray diffraction (PXRD) spectroscopy and thermogravimetric analysis (TGA). The structural attributes of PROD-1 and PROD-2 render them promising materials for future photocatalytic investigations.

https://dx.doi.org/10.3390/molecules26102955

Structural Effects of meso-Halogenation on Porphyrins

Flanagan, K.J., Paradiz Dominguez, M., Melissari, Z., Eckhardt, H.-G., Williams, R.M., Gibbons, D., Prior, C., Locke, G.M., Meindl, A., Ryan, A.A., Senge, M.O., Structural Effects of meso-Halogenation on Porphyrins, Beilstein J. Org. Chem. 2021, 17, 1149-1170.

The use of halogens in the crystal engineering of supramolecular porphyrin assemblies has been a topic of strong interest over the past decades. With this in mind we have characterized a series of direct meso-halogenated porphyrins using single crystal X-ray crystallography. This is accompanied by a detailed conformational analysis of all deposited meso-halogenated porphyrins in the CSD. In this study we have used the Hirshfeld fingerprint plots together with normal-coordinate structural decomposition and determined crystal structures to elucidate the conformation, present intermolecular interactions, and compare respective contacts within the crystalline architectures. Additionally, we have used density functional theory calculations to determine the structure of several halogenated porphyrins. This contrasts conformational analysis with existing X-ray structures and gives a method to characterize samples that are difficult to crystallize. By using the methods outlined above we were able to deduce the impact a meso halogen has on a porphyrin, for example, meso-halogenation is dependent on the type of alternate substituents present when forming supramolecular assemblies. Furthermore, we have designed a method to predict the conformation of halogenated porphyrins, without need of crystallization, using DFT calculations with a high degree of accuracy.

https://dx.doi.org/10.3762/bjoc.17.88

Classic highlights in porphyrin and porphyrinoid total synthesis and biosynthesis

Senge, M.O., Sergeeva, N.N., Hale, K.J., Classic highlights in porphyrin and porphyrinoid total synthesis and biosynthesis, Chem. Soc. Rev. 2021, 50, 4730-4789.

Porphyrins feature prominently in nature, be it as enzymatic cofactors, electron and exciton shuffles, as photoactive dyes, or as signaling substances. Their involvement in the generation, storage and use of oxygen is pivotal to life, while their photochemical properties are central to the biochemical functioning of plants. When complexed to metals, porphyrins can engage in a multitude of contemporary applications ranging from solar energy generation to serving as catalysts for important chemical reactions. They are also able to function as useful theranostic agents, and as novel materials for a wide range of applications. As such, they are widely considered to be highly valuable molecules, and it almost goes without saying that synthetic organic chemistry has dramatically underpinned all the key advances made, by providing reliable access to them. In fact, strategies for the synthesis of functionalized porphyrins have now reached a state of refinement where pretty well any desired porphyrin can successfully be synthesized with the approaches that are available, including a cornucopia of related macrocycle-modified porphyrinoids. In this review, we are going to illustrate the development of this exciting field by discussing a number of classic syntheses of porphyrins. Our coverage will encompass the natural protoporphyrins and chlorophylls, while also covering general strategies for the synthesis of unsymmetrical porphyrins and chlorins. Various industrial syntheses of porphyrins will also be discussed, as will other routes of great practical importance, and avenues to key porphyrinoids with modified macrocycles. A range of selected examples of contemporary functionalization reactions will be highlighted. The various key syntheses will be described and analyzed from a traditional mechanistic organic chemistry perspective to help student readers, and those who are new to this area. The aim will be to allow readers to mechanistically appreciate and understand how many of these fascinating ring-systems are built and further functionalized.

https://dx.doi.org/10.1039/C7CS00719A

Quantitative Structure-Property Relationship Modelling for the Prediction of Singlet Oxygen Generation by Heavy-atom-free BODIPY Photosensitizers

Buglak, A.A., Charisiadis, A., Sheehan, A., Kingsbury, C.J., Senge, M.O., Filatov, M.A., Quantitative Structure-Property Relationship Modelling for the Prediction of Singlet Oxygen Generation by Heavy-atom-free BODIPY Photosensitizers, Chem. Eur. J. Accepted Author Manuscript, 2021.

Heavy-atom-free sensitizers forming long-living triplet excited states via the spin-orbit charge transfer intersystem crossing (SOCT-ISC) process have potential to replace transition metal complexes in photonic applications. The efficiency of SOCT-ISC in BODIPY donor-acceptor dyads can be tuned by structural modification. Predicting the triplet state yields and reactive oxygen species generation quantum yields in a particular solvent is challenging due to a lack of quantitative structure-property relationship (QSPR) models. We analyzed data on 1O2 generation quantum yields (ΦΔ) for >70 heavy-atom-free BODIPY in toluene, acetonitrile, and THF. To build reliable QSPR models, we synthesized new BODIPYs containing different electron donating groups, studied their optical and structural properties and the solvent dependence of 1O2, which confirmed the formation of triplet states via SOCT-ISC. More than 5000 quantum-chemical descriptors were calculated including descriptors using DFT, namely M06-2X functional. QSPR models predicting ΦΔ values were developed using multiple linear regression (MLR), which perform significantly better than other machine learning methods and show sufficient statistical parameters (R = 0.88-0.91 and q2 = 0.62-0.69) for all three solvents. A small root mean squared error of 8.2% was obtained for ΦΔ values predicted using MLR model in toluene. QSPR and machine learning techniques can be useful for predicting ΦΔ values in different media and virtual screening of new heavy-atom-free BODIPYs with improved photosensitizing ability.

https://dx.doi.org/10.1002/chem.202100922

The human tRNA-guanine transglycosylase displays promiscuous nucleobase preference but strict tRNA specificity

Fergus, C., Al-qasem, M., Cotter, M., McDonnell, C.M., Sorrentino, E., Chevot, F., Hokamp, K., Senge, M.O., Southern, J.M., Connon, S.J., Kelly V.P., The human tRNA-guanine transglycosylase displays promiscuous nucleobase preference but strict tRNA specificity, Nucleic Acids Research. 2021, 49(9), 4877-4890.

Base-modification can occur throughout a transfer RNA molecule; however, elaboration is particularly prevalent at position 34 of the anticodon loop (the wobble position), where it functions to influence protein translation. Previously, we demonstrated that the queuosine modification at position 34 can be substituted with an artificial analogue via the queuine tRNA ribosyltransferase enzyme to induce disease recovery in an animal model of multiple sclerosis. Here, we demonstrate that the human enzyme can recognize a very broad range of artificial 7-deazaguanine derivatives for transfer RNA incorporation. By contrast, the enzyme displays strict specificity for transfer RNA species decoding the dual synonymous NAU/C codons, determined using a novel enzymeRNA capture-release method. Our data highlight the broad scope and therapeutic potential of exploiting the queuosine incorporation pathway to intentionally engineer chemical diversity into the transfer RNA anticodon.

https://dx.doi.org/10.1093/nar/gkab289

Dipyrrinato-Iridium(III) Complexes for Application in Photodynamic Therapy and Antimicrobial Photodynamic Inactivation

Hohlfeld, B.F., Gitter, B., Kingsbury, C.J., Flanagan, K.J., Steen, D., Wieland, G.D., Kulak, N., Senge, M.O., Wiehe, A. Dipyrrinato-Iridium(III) Complexes for Application in Photodynamic Therapy and Antimicrobial Photodynamic Inactivation. Chem. Eur. J. 2021, 27, 6440-6459.

The generation of bio-targetable photosensitizers is of utmost importance to the emerging field of photodynamic therapy and antimicrobial (photo-)therapy. A synthetic strategy is presented in which chelating dipyrrin moieties are used to enhance the known photoactivity of iridium(III) metal complexes. Formed complexes can thus be functionalized in a facile manner with a range of targeting groups at their chemically active reaction sites. Dipyrrins with N- and O-substituents afforded (dipy)iridium(III) complexes via complexation with the respective Cp*-iridium(III) and ppy-iridium(III) precursors (dipy=dipyrrinato, Cp*=pentamethyl-η5-cyclopentadienyl, ppy=2-phenylpyridyl). Similarly, electron-deficient [IrIII(dipy)(ppy)2] complexes could be used for post-functionalization, forming alkenyl, alkynyl and glyco-appended iridium(III) complexes. The phototoxic activity of these complexes has been assessed in cellular and bacterial assays with and without light; the [IrIII(Cl)(Cp*)(dipy)] complexes and the glyco-substituted iridium(III) complexes showing particular promise as photomedicine candidates. Representative crystal structures of the complexes are also presented.

https://dx.doi.org/10.1002/chem.202004776

Crystal structures of 4-bromo-2-formyl-1-tosyl-1H-pyrrole, (E)-4-bromo-2-(2-nitrovinyl)-1-tosyl-1H-pyrrole and 6-(4-bromo-1-tosylpyrrol-2-yl)-4,4-dimethyl-5-nitrohexan-2-one

Kingsbury, C. J., Sample, H., Senge, M. O., Crystal structures of 4-bromo-2-formyl-1-tosyl-1H-pyrrole, (E)-4-bromo-2-(2-nitrovinyl)-1-tosyl-1H-pyrrole and 6-(4-bromo-1-tosylpyrrol-2-yl)-4,4-dimethyl-5-nitrohexan-2-one., Acta Cryst. 2021, E77, 341-345.

The crystal structures of three intermediate compounds in the synthesis of 8-bromo-2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin are reported; 4-bromo-2-formyl-1-tosyl-1H-pyrrole, C12H10BrNO3S, (E)-4-bromo-2-(2-nitrovinyl)-1-tosyl-1H-pyrrole, C13H11BrN2O4S, and 6-(4-bromo-1-tosylpyrrol-2-yl)-4,4-dimethyl-5-nitrohexan-2-one, C19H23BrN2O5S. The compounds show multitudinous intermolecular C—H⋯O interactions, with bond distances and angle consistent in the series and within expectations, as well as varied packing types. The merits of collecting data beyond the standard resolution usually reported for small molecules are discussed.

https://dx.doi.org/10.1107/S2056989021002280

An Insight into Non-Covalent Interactions on the Bicyclo[1.1.1]pentane Scaffold

Grover, N., Flanagan, K.J., Trujillo, C., Kingsbury, C.J. and Senge, M.O. An Insight into Non-Covalent Interactions on the Bicyclo[1.1.1]pentane Scaffold. Eur. J. Org. Chem. 2021, 2021(7), 1113-1122.

The effect of bridgehead substitutions on non-covalent interactions was investigated for seven BCP derivatives. The X-ray analyses show 3D-structures and a combination of non-covalent interactions including HB, XB and CH⋯HC contacts. QTAIM analysis and MEP graphs show the presence of bond critical points and σ-holes.

https://dx.doi.org/10.1002/ejoc.202001564

Structural, Photophysical, and Photobiological Studies on BODIPY-Anthracene Dyads

Callaghan, S., Vindstad, B.E., Flanagan, K.J., Melø, T.B., Lindgren, M., Grenstad, K., Gederaas, O.A. and Senge, M.O., Structural, Photophysical, and Photobiological Studies on BODIPY-Anthracene Dyads. ChemPhotoChem. 2020 5(2), 131-141

We report the structural, photophysical, and photobiological properties of a promising BODIPY-anthracene dyad (BAD) that was previously shown to induce a therapeutic effect against MDA-MB-468ߕcells. The BODIPY was synthesized and its crystal structure was elucidated. We further investigate the potential of this molecule as a versatile photosensitizer for photodynamic therapy against AY27 and F98 cancer cell models. Both necrosis and apoptosis were found to play a role in cell death and G1 phase arrestation was observed following PDT. From time-resolved spectroscopic analysis of absorbance and luminescence, it was found that the singlet oxygen quantum yield of the most promising BODIPY-anthracene dyad is high (>70 %) and originates from a triplet state. Interestingly, despite the efficient PDT effect, long-lived triplet states or singlet oxygen formation were not observed when water (or D2O) was used as the solvent but were readily observed in solvents such as MeOH and EtOH.

https://dx.doi.org/10.1002/cptc.202000191

Strategic synthesis of ′picket fence′ porphyrins based on nonplanar macrocycles

Norvaiša, K., Yeow, K., Twamley, B., Roucan, M., Senge. M. O., Strategic Synthesis of ′Picket Fence′ Porphyrins Based on Nonplanar Macrocycles. Eur. J. Org. Chem. 2021, 1871-1882

Traditional ′picket fence′ porphyrin systems have been a topic of interest for their capacity to direct steric shielding effects selectively to one side of the macrocycle. Sterically overcrowded porphyrin systems that adopt macrocycle deformations have recently drawn attention for their applications in organocatalysis and sensing. Here we explore the combined benefits of nonplanar porphyrins and the old molecular design to bring new concepts to the playing field.

https://dx.doi.org/10.1002/ejoc.202100154

Investigation of the Reactivity of 1-Azido-3-iodobicyclo[1.1.1]pentane under ″Click″ Reaction Conditions

Sitte, E., Twamley, B., Grover, N., Senge, M. O., Investigation of the Reactivity of 1-Azido-3-iodobicyclo[1.1.1]pentane under ″Click″ Reaction Conditions, J. Org. Chem 2021, 86, 1238-1245.

The bicyclo[1.1.1]pentane (BCP) unit is under scrutiny as a bioisostere in drug molecules. We employed methodologies for the synthesis of different BCP triazole building blocks from one precursor, 1-azido-3-iodobicyclo[1.1.1]pentane, by ″click″ reactions and integrated cycloaddition—Sonogashira coupling reactions. Thereby, we accessed 1,4-disubstituted triazoles, 5-iodo-1,4,5-trisubstituted triazoles, and 5-alkynylated 1,4,5-trisubstituted triazoles. This gives entry to the synthesis of multiply substituted BCP triazoles on either a modular or a one-pot basis. These methodologies were further utilized for appending porphyrin moieties onto the BCP core.

https://dx.doi.org/10.1021/acs.joc.0c02432

The Shape of Porphyrins

Kingsbury, C. J., Senge, M. O., The shape of porphyrins, Coord. Chem. Rev, 2021, 431, 213760

Porphyrin molecules are a widely exploited biochemical moiety, with uses in medicinal chemistry, sensing and materials science. The shape of porphyrins, as an aromatic unit, is reductively imagined to be approximately flat, with regular, rigid shape, owing to the popular depiction as a simplified skeletal model. While this regular conformation does exist, the array of substitution patterns in synthetic porphyrins or interactions with the apoprotein in biochemical moieties often induce distortions both in-plane and out-of-plane. Structural deviation reduces symmetry from the ideal D4h and can introduce changes in the physical and electronic structure; physical changes can introduce pockets for favorable intermolecular interactions, and electronic distortion can introduce new electronic transitions and properties. A quantification of porphyrin distortion is presented based on the Normal-coordinate Structural Decomposition method (NSD) pioneered by Shelnutt.

https://dx.doi.org/10.1016/j.ccr.2020.213760.

Elucidating Atropisomerism in Nonplanar Porphyrins with Tunable Supramolecular Complexes

Norvaiša, K., O'Brien, J. E., Gibbons, J. D. and Senge, M. O., Elucidating Atropisomerism in Nonplanar Porphyrins with Tunable Supramolecular Complexes, Chem. Eur. J., 2020, 27, 331-339

Atropisomerism is a fundamental feature of substituted biaryls resulting from rotation around the biaryl axis. Different stereoisomers are formed due to restricted rotation about the single bond, a situation often found in substituted porphyrins. Previously NMR determination of porphyrin atropisomers proved difficult, if not almost impossible to accomplish, due to low resolution or unresolvable resonance signals that predominantly overlapped. Here, we shed some light on this fundamental issue found in porphyrinoid stereochemistry. Using benzenesulfonic acid (BSA) for host—guest interactions and performing 1D, 2D NMR spectroscopic analyses, we were able to characterize all four rotamers of the nonplanar 5,10,15,20-tetrakis(2-aminophenyl)-2,3,7,8,12,13,17,18- octaethylporphyirin as restricted H-bonding complexes.

https://dx.doi.org/10.1002/chem.202003414

Nucleophilic Aromatic Substitution (SNAr) and Related Reactions of Porphyrinoids: Mechanistic and Regiochemical Aspects

Sample, H. C., Senge, M. O., Nucleophilic Aromatic Substitution (SNAr) and Related Reactions of Porphyrinoids: Mechanistic and Regiochemical Aspects, Eur. J. Org. Chem., 2021, (1), 7-42

The nucleophilic substitution of aromatic moieties (SNAr) has been known for over 150 years and found wide use for the functionalization of (hetero)aromatic systems. At current, several ′types′ of SNAr reactions have been established and notably the area of porphyrinoid macrocycles has seen many uses thereof. Herein we detail the SNAr reactions of seven types of porphyrinoids...

https://dx.doi.org/10.1002/ejoc.202001183

Synthetic Advances in the C—H Activation of Rigid Scaffold Molecules

Grover, N.; Senge, M. O., Synthetic Advances in the C—H Activation of Rigid Scaffold Molecules, Synthesis, 2020, 52(22), 3295-3325

The remarkable structural and electronic properties of rigid non-conjugated hydrocarbons afford attractive opportunities to design molecular building blocks for both medicinal and material applications. The bridgehead positions provide the possibility to append diverse functional groups at specific angles and in specific orientations. The current review summarizes the synthetic development in CH functionalization of three rigid scaffolds namely: (a) cubane, (b) bicyclo[1.1.1]pentane (BCP), (c) adamantane.

https://dx.doi.org/10.1055/s-0040-1707884

Synthesis and Structure of meso-Substituted Dibenzihomoporphyrins

Grover, N.; Emandi, G.; Twamley, B.; Khurana, B.; Sol, V.; Senge, M. O. Synthesis and Structure of meso-Substituted Dibenzihomoporphyrins Eur. J. Org. Chem. 2020, 2020(41) 6489-6496

Bench-stable meso-substituted di(p/m-benzi)homoporphyrins were synthesized through acid-catalyzed condensation of dipyrrole derivatives with aryl aldehydes. The insertion of a 1,1,2,2-tetraphenylethene (TPE) or but-2-ene-2,3-diyldi11 benzene unit in the porphyrin framework results in the formation of dibenzihomoporphyrins, merging the features of hydrocarbons and porphyrins. Single crystal X-ray analyses established the non-planar structure of these molecules, with the phenylene rings out of the mean plane, as defined by the dipyrromethene moiety and the two meso-carbon atoms. Spectroscopic and structural investigations show that the macrocycles exhibit characteristics of both TPE or but-2-ene-2,3-diyldibenzene and dipyrromethene units indicating the nonaromatic characteristics of the compounds synthesized. Additionally, the dibenzihomoporphyrins were found to generate singlet oxygen, potentially allowing their use as photosensitizers.

https://dx.doi.org/10.1002/ejoc.202001165

Influence of meso-linker attachment on the formation of core⋯ℼ interactions in urea-functionalized porphyrins.

Flanagan, K. J.; Ryan, A. A.; Twamley, B.; Senge, M. O.; Influence of meso-linker attachment on the formation of core⋯ℼ interactions in urea-functionalized porphyrins. Zeitschrift für Naturforschung 2020, 75b, 755-764.

The ability to cover the face of a porphyrin macrocycle selectively is an attractive feature for concepts such as catalysis and anion binding that is reliant on porphyrin core interactions. Herein, we have synthesized a family of mono-urea functionalized porphyrin complexes with intent to investigate their potential to form core···Π interactions selectively to one face of the porphyrin macrocycle. By altering the distance between the urea moiety and the porphyrin through direct linkage or introducing a linker group we can control the formation of the core interactions.

https://dx.doi.org/10.1515/znb-2020-0099

Synthesis and spectral properties of gem-dimethyl chlorin photosensitizers

Melissari, Z., Sample, H. C., Twamley, B., Williams, R. M. and Senge, M. O., Synthesis and spectral properties of gem-dimethyl chlorin photosensitizers, ChemPhotoChem, 2020, 4, 601-611.

Chlorins that bear a gem-dimethyl group, which attributes their resistance to oxidation, are of interest for applications in photomedicine. Herein, we present the synthesis and the photophysical properties of two geminal-dimethyl chlorins (dihydroporphyrins) and their free base counterparts that act as efficient singlet oxygen generators and thus exhibit potential for use in photodynamic therapy (PDT) as anticancer or antimicrobial agents upon further derivatization.

https://dx.doi.org/10.1002/cptc.202000051

Dual-binding conjugates of diaromatic guanidines and porphyrins for recognition of G-quadruplexes

Grover, J.; Trujillo, C.; Saad, M.; Emandi, G.; Stipanišev, N.; Bernhard, S. S. R., Guédin, A.; Mergny, J.-L.; Senge, M. O.; Rozas, I.; Dual-binding conjugates of diaromatic guanidines and porphyrins for recognition of G-quadruplexes. Org. Biomol. Chem. 2020, 18, 5617—5624.

The first conceptualised class of dual-binding guanine quadruplex binders has been designed, synthesised and biophysically studied. These compounds combine diaromatic guanidinium systems and neutral tetra-phenylporphyrins (classical binding moiety for guanine quadruplexes) by means of a semi-rigid linker. An extensive screening of a variety of guanine quadruplex structures and double stranded DNA via UV-vis, FRET and CD experiments revealed the preference of the conjugates towards guanine quadruplexes.

https://dx.doi.org/10.1039/D0OB01264E

Graphene Oxide Functionalized with Cationic Porphyrins as Materials for the Photodegradation of Rhodamine B.

Larowska, D.; O′Brien, J. M.; Senge, M. O.; Burdzinski, G.; Marciniak, B.; Lewandowska-Andralojc, A.; Graphene Oxide Functionalized with Cationic Porphyrins as Materials for the Photodegradation of Rhodamine B. J. Phys. Chem. C 2020, 124, 15769—15780

Two noncovalent nanohybrids between cationic porphyrin (free-base TMPyP and zinc(II) ZnTMPyP) bearing cationic (N-methylpyridyl) groups and graphene oxide (GO) were constructed with the aim of generating a photocatalyst active for rhodamine B (RhB) degradation. The obtained materials were thoroughly characterized by steady-state and time-resolved absorption and emission methods, which indicated that metalation of the porphyrin with Zn(II) increases the affinity of the porphyrin toward the GO surface. Photocurrent experiment together with femtosecond transient absorption spectroscopy clearly showed the existence of electron transfer from the photoexcited porphyrin to GO.

https://dx.doi.org/10.1021/acs.jpcc.0c03907

Synthesis, characterization, and crystal structure analysis of Zn(II) and Cd(II) coordination compounds containing 4-((pyridin-4-ylmethylene)amino)phenol Schiff-base ligand.

Hajiashrafi, T.; Salehi, S.; Kubicki, M.; Flanagan, K. J.; Senge, M. O.; Synthesis, characterization, and crystal structure analysis of Zn(II) and Cd(II) coordination compounds containing 4-((pyridin-4-ylmethylene)amino)phenol Schiff-base ligand. J. Mol. Struc. 2020, 1221, 128846.

Zn(II) and Cd(II) coordination compounds containing 4-((pyridin-4-ylmethylene)amino)phenol ligands were synthesized and then characterized using spectroscopic techniques and single crystal X-ray crystallography.

https://dx.doi.org/10.1016/j.molstruc.2020.128846

Weak Interactions and Conformational Changes in Core-Protonated A2- and Ax-Type Porphyrin Dications

Kingsbury, C.J.; Flanagan, K.J.; Eckhardt, H.-G.; Kielmann, M.; Senge, M.O. Weak Interactions and Conformational Changes in Core-Protonated A2- and Ax-Type Porphyrin Dications, Molecules 2020, 25, 3195

Individual chemical motifs are known to introduce structural distortions to the porphyrin macrocycle, be it in the core or at the periphery of the macrocycle. The interplay when introducing two or more of these known structural motifs has been scarcely explored and is not necessarily simply additive; these structural distortions have a chance to compound or negate to introduce new structural types. To this end, a series of compounds with complementary peripheral (5,15-disubstitution) and core (acidification) substitution patterns were investigated. The single-crystal X-ray structures of 18 5,15-diphenylporphyrin, 5,15-diphenylporphyrindi-ium diacid, and related compounds are reported, including the first example of a 5,15-dialkylporphyrindi-ium. Normal-coordinate structural decomposition (NSD) analysis is used for a detailed analysis of the conformation of the porphyrin subunit within the crystal structures.

https://dx.doi.org/10.3390/molecules25143195

Porphyrins as Colorimetric and Photometric Biosensors in Modern Bioanalytical Systems

Norvaiša, K., Kielmann, M. and Senge, M. O., Porphyrins as Colorimetric and Photometric Biosensors in Modern Bioanalytical Systems, ChemBioChem, 2020, 21, 1793-1807.

Chlorins that bear a gem-dimethyl group, which attributes their resistance to oxidation, are of interest for applications in photomedicine. Herein, we present the synthesis and the photophysical properties of two geminal-dimethyl chlorins (dihydroporphyrins) and their free base counterparts that act as efficient singlet oxygen generators and thus exhibit potential for use in photodynamic therapy (PDT) as anticancer or antimicrobial agents upon further derivatization...

https://dx.doi.org/10.1002/cbic.202000067

Targeted Synthesis of Regioisomerically Pure Dodecasubstituted Type I Porphyrins through the Exploitation of Peri-interactions

Kielmann, M.; Flanagan, K. J.; Senge, M. O. Targeted Synthesis of Regioisomerically Pure Dodecasubstituted Type I Porphyrins through the Exploitation of Peri-interactions. J. Org. Chem. 2020, 85, 7603—7610

A targeted synthesis of dodecasubstituted type I porphyrins that utilizes the reaction of unsymmetrical 3,4-difunctionalized pyrroles and sterically demanding aldehydes was developed. This way, type I porphyrins could be obtained as the only type isomers, likely due to a minimization of the steric strain arising from peri-interactions. Uniquely, this method does not depend on lengthy precursor syntheses, the separation of isomers, or impractical limitations of the reaction scale. In addition, single crystal X-ray analysis elucidated the structural features of the macrocycles.

https://dx.doi.org/10.1021/acs.joc.0c00798

The Red Color of Life Transformed - Synthetic Advances and Emerging Applications of Protoporphyrin IX in Chemical Biology

Sitte, E. and Senge, M. O., The Red Color of Life Transformed - Synthetic Advances and Emerging Applications of Protoporphyrin IX in Chemical Biology, Eur. J. Org. Chem., 2020, 22, 3171-3191

The use of the heme precursor protoporphyrin IX for biological applications has experienced a steep increase in recent years. Herein, we review possibilities for synthetic modification of this porphyrin scaffold and discuss its emerging key uses in the field of chemical biology.

https://dx.doi.org/10.1002/ejoc.202000074

Short-Chained Anthracene Strapped Porphyrins and their Endoperoxides

Callaghan, S.; Flanagan, K. J.; O'Brien, J. E. and Senge, M. O., Short-Chained Anthracene Strapped Porphyrins and their Endoperoxides, Eur. J. Org. Chem., 2020, 2020 18, 2735-2744.

Herein, we report the synthesis of three short-chained anthracene strapped porphyrins and their corresponding endoperoxides, formed by a cycloaddition reaction between in situ generated singlet oxygen and the anthracene moiety. We also synthesized Zn(II)complexes of the strapped porphyrins. X-ray crystallography and UV/Vis analysis confirmed macrocyclic distortion in the strapped systems.

https://dx.doi.org/10.1002/ejoc.202000283

Towards triptycene functionalization and triptycene-linked porphyrin arrays

Locke, G.M.; Flanagan, K.J. and Senge, M.O., Towards triptycene functionalization and triptycene-linked porphyrin arrays, Beilstein J. Org. Chem. 2020, 16, 763-777.

Herein, 9,10-diethynyltriptycene is investigated for its use as a rigid isolating unit in the synthesis of multichromophoric arrays. Sonogashira cross-coupling conditions are utilized to attach various porphyrins and boron dipyrromethenes (BODIPYs) to the triptycene scaffold. While there are previous examples of triptycene porphyrin complexes, this work reports the first example of a linearly connected porphyrin dimer, linked through the bridgehead carbons of triptycene.

https://dx.doi.org/10.3762/bjoc.16.70

Exploring the Relationship Between Structure and Activity in BODIPYs Designed for Antimicrobial Phototherapy

Hohlfeld, B. F., Gitter, B., Flanagan, K., Kingsbury, C. J., Kulak, N., Senge, M. O., & Wiehe, A., Exploring the Relationship Between Structure and Activity in BODIPYs Designed for Antimicrobial Phototherapy. Org. Biomol. Chem., 2020, 18, 2416-2431.

A synthetic strategy to BODIPY dyes is presented giving access to a range of new compounds relevant in the context of antimicrobial photodynamic therapy (aPDT). BODIPYs with the 8-(4-fluoro-3-nitrophenyl) and the 8-pentafluorophenyl substituents were used for the synthesis of new mono- and dibrominated BODIPYs.

https://dx.doi.org/10.1039/d0ob00188k

Synthesis, crystal structure, and ADME prediction studies of novel imidazopyrimidines as antibacterial and cytotoxic agents

Abdel-Mohsen, H. T.; Abood, A.; Flanagan, K. J.; Meindl, A.; Senge, M. O. and El Diwani, H. I., Synthesis, crystal structure, and ADME prediction studies of novel imidazopyrimidines as antibacterial and cytotoxic agents, Arch. Pharm. Chem. Life Sci., 2020, 353, 3, 1900271.

In the present study, a novel series of polyfunctionalized imidazopyrimidines 6a-u and 9a-d were efficiently constructed by a domino reaction between 2-imino-6-substituted-2,3-dihydropyrimidin-4(1H)-ones 4a-d or 8a-c and 2-bromoacetophenones 5a-i under mild basic conditions. The synthesized series were screened for their antibacterial activity against Staphylococcus aureus and Bacillus subtilis as Gram-positive (+) bacteria, as well as against Gram-negative (-) bacteria Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella typhi.

https://dx.doi.org/10.1002/ardp.201900271

Organische Chemie.

Andexer, J. N.; Beifuss, U.; Beuerle, F.; Brasholz, M.; Breinbauer, R.; Ernst, M.; Greb, J.; Gulder, T.; Hüttel, W.; Kath-Schorr, S.; Kordes, M.; Lehmann, M.; Lindel, T.; Luy, B.; Mück-Lichtenfeld, C.; Muhle, C.; Narine, A.; Niemeyer, J.; Paradies, J.; Pfau, R.; Pietruszka, J.; Schaschke, N.; Senge, M. O.; Straub, B. F.; Werner, T.; Werz, D. B.; Winter, C. Organische Chemie. Nachrichten aus der Chemie, 2020, 68, 42—72.\

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https://dx.doi.org/10.1002/nadc.20204095515

Bridging and Conformational Control of Porphyrin Units through Non-Traditional Rigid Scaffolds

Grover, N.; Locke, G. M.; Flanagan, K. J.; Beh, M. H. R.; Thompson, A.; Senge, M. O. Chem. Eur. J. 2020, 26, 2405-2416.

Connecting two porphyrin units in a rigid linear fashion, without any undesired electron delocalization or communication between the chromophores, remains a synthetic challenge. Herein, a broad library of functionally diverse multi-porphyrin arrays that incorporate the non-traditional rigid linker groups cubane and bicyclo[1.1.1]pentane (BCP) is described. A robust, reliable, and versatile synthetic procedure was employed to access porphyrin-cubane/BCP-porphyrin arrays, representing the largest non-polymeric structures available for cubane/BCP derivatives.

https://dx.doi.org/10.1002/chem.201904199

Targeting Receptor TyrosineKinase VEGFR-2 in Hepatocellular Cancer:Rational Design, Synthesis and Biological Evaluation of 1,2-Disubstituted Benzimidazoles.

Abdel-Mohsen, H. T.; Abdullaziz, M. A.; El Kerdawy, A. M.; Ragab, F. A. F.; Flanagan, K. J.; Mahmoud, A. E. E.; Ali, M. M.; El Diwani, H. I.; Senge, M. O. Targeting Receptor TyrosineKinase VEGFR-2 in Hepatocellular Cancer:Rational Design, Synthesis and Biological Evaluation of 1,2-Disubstituted Benzimidazoles. Molecules, 2020, 25, 770

In this study, a novel series of 1,2-disubstituted benzo[d]imidazoles was rationally designed as VEGFR-2 inhibitors targeting hepatocellular carcinoma. Our design strategy is two-fold; it aimed first at studying the effect of replacing the 5-methylfuryl moiety of the well-known antiangiogenic 2-furylbenzimidazoles with an isopropyl moiety on the VEGFR-2 inhibitory activity and the cytotoxic activity. Our second objective was to further optimize the structures of the benzimidazole derivatives through elongation of the side chains at their one-position for the design of more potent type II-like VEGFR-2 inhibitors. The designed 1,2-disubstituted benzimidazoles demonstrated potent cytotoxic activity against the HepG2 cell line, reaching IC50 = 1.98 ΜM in comparison to sorafenib (IC50 = 10.99 ΜM).

https://dx.doi.org/10.3390/molecules25040770

Crystal structures of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl)porphyrin as the chloroform monosolvate and tetrahydrofuran monosolvate

Kingsbury, C. J., Flanagan, K. J., Kielmann, M., Twamley, B. and Senge, M.O.; Crystal structures of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl)porphyrin as the chloroform monosolvate and tetrahydrofuran monosolvate; Acta Cryst. 2020, E76, 214-220.

The crystal structures of the title compounds, two solvates (CHCl3 and THF) of a symmetric and highly substituted porphyrin, C44H2Br8F20N4 or OBrTPFPP, are described.

https://dx.doi.org/10.1107/S2056989020000432

Ethynylphenyl-Derivatized Free Base Porphyrins: Anodic Oxidation Processes and Covalent Grafting onto Glassy Carbon Electrodes

Gamm, P.; Sheridan, M. V.; Van Wyck, S.J.; Meindl, A.; Senge, M.O. and Geiger, W.E.; Ethynylphenyl-Derivatized Free Base Porphyrins: Anodic Oxidation Processes and Covalent Grafting onto Glassy Carbon Electrodes, Langmuir, 2020, 36, 1, 96-108.

In six of seven cases, direct anodic oxidation of the ethynyl group of an ethynylphenyl-derivatized free-base porphyrin gave modified glassy carbon electrodes in which the porphyrin was strongly surface-bound, most likely in a perpendicular geometry through covalent attachment of the ethynyl group to a surface carbon atom.

https://dx.doi.org/10.1021/acs.langmuir.9b03452

Investigating the Impact of Conformational Molecular Engineering on the Crystal Packing of Cavity Forming Porphyrins

Flanagan, K. J., Twamley, B. and Senge, M. O., Investigating the Impact of Conformational Molecular Engineering on the Crystal Packing of Cavity Forming Porphyrins, Inorg. Chem., 2019, 58, 23, 15769-15787.

Herein we report the synthesis of 5,10,15,20-tetraaryl-(X)-substituted-2,3,7,8,12,13,17,18-octaethylporphyrins (OETArXPs) and a structural investigation of their solid-state properties via small molecule X-ray diffraction. A series of halogen (fluorine to iodine), nitrogenous (azido, cyano), alkyl (TMS-acetylene and acetylene), and chained (benzyloxy) porphyrins were chosen as the initial target molecules. Following this, a selection of tetravalent metal complexes [Cu(II), Ni(II), and Pd(II)] based on these porphyrins were synthesized to allow for an investigation of the effects of metal complexes on the structural properties of these highly substituted porphyrins.

https://dx.doi.org/10.1021/acs.inorgchem.9b01963

Cell death in photodynamic therapy: From oxidative stress to anti-tumor immunity

Donohoe, C., Senge, M. O., Arnaut, L. G. and Gomes-da-Silva, L. C., Cell death in photodynamic therapy: From oxidative stress to anti-tumor immunity. Biochim. Biophys. Acta, Rev. Cancer 2019, 1872, 188308.

Photodynamic therapy is a promising approach for cancer treatment that relies on the administration of a photosensitizer followed by tumor illumination. The generated oxidative stress may activate multiple mechanisms of cell death which are counteracted by cells through adaptive stress responses that target homeostasis rescue.

https://dx.doi.org/10.1016/j.bbcan.2019.07.003

Conformational remodeling of porphyrins as receptors with switchable N-H⋯X binding modes

Norvaiša, K., Flanagan, K. J., Gibbons, D. & Senge, M. O., Conformational Remodeling of Porphyrins as Receptors with Switchable N-H...X Binding Modes, Angew. Chem. Int. Ed., 2019, 58, 46, 16553-16557

The selectivity and functional variability of porphyrin factors is typically based on substrate binding by metalloporphyrins, with the pyrrole nitrogen atoms only serving to chelate the metal ions. In a first step to porphyrin centers with "enzyme-like" activity, a structural and spectroscopic investigation shows ...

https://dx.doi.org/10.1002/anie.201907929

Hydrogels: Soft matters in photomedicine

Khurana, B., Gierlich, P., Meindl, A., Gomes-da-Silva, L.C. & Senge, M.O., Hydrogels: Soft matters in photomedicine, Photochem. Photobiol. Sci., 2019, 18, 2613-2656.

Photodynamic therapy (PDT), a shining beacon in the realm of photomedicine, is a non-invasive technique that utilizes dyebased photosensitizers (PSs) in conjunction with light and oxygen to produce reactive oxygen species to combat malignant tissue and infectious microorganisms. Yet, for PDT to become a common, routine therapy, it is still necess...

https://dx.doi.org/doi:10.1039/c9pp00221a

Trends and targets in antiviral phototherapy

Wiehe, A., O'Brien, J. M. & Senge, M. O., Trends and targets in antiviral phototherapy, Photochem. Photobiol. Sci., 2019, 18, 2565-2612.

Photodynamic therapy (PDT) is a well-established treatment option in the treatment of certain cancerous and pre-cancerous lesions. Though best-known for its application in tumor therapy, historically the photodynamic ...

https://dx.doi.org/10.1039/C9PP00211A

Solid-state supramolecular architectures of a series of Hg(ii) halide coordination compounds based on hydroxyl-substituted Schiff base ligands.

Hajiashrafi, T.; Salehi, S.; Kubicki, M.; Bauzà, A.; Frontera, A.; Flanagan, K. J.; Senge, M. O., Solid-state supramolecular architectures of a series of Hg(ii) halide coordination compounds based on hydroxyl-substituted Schiff base ligands. CrystEngComm., 2019, 21, 6301-6312.

Crystal engineering of coordination complexes has become an important research domain of modern inorganic chemistry. Herein, six Hg(II) coordination compounds containing 2-((pyridin-3-ylmethylene)amino)phenol and 4-((pyridin-4-ylmethylene)amino)phenol ligands were synthesized and characterized by single crystal X-ray crystallography and spectroscopic techniques

https://dx.doi.org/10.1021/acs.jpcc.9b03718

A hydroxamic-acid-containing nucleoside inhibits DNA repair nuclease SNM1A.

Doherty, W.; Dürr, E.-M.; Baddock, H. T.; Lee, S. Y.; McHugh, P. J.; Brown, T.; Senge, M. O., Scanlan, E. M.; McGouran, J. F., A hydroxamic-acid-containing nucleoside inhibits DNA repair nuclease SNM1A, Org. Biomol. Chem., 2019, 17, 8094-8105.

Nine modified nucleosides, incorporating zinc-binding pharmacophores, have been synthesised and evaluated as inhibitors of the DNA repair nuclease SNM1A. The series included oxyamides, hydroxamic acids, hydroxamates, a hydrazide, a squarate ester and a squaramide. A hydroxamic acid-derived nucleoside inhibited the enzyme, offering a novel approach for potential therapeutic development through the use of rationally designed nucleoside derived inhibitors.

https://dx.doi.org/10.1039/C9OB01133A

A lead BODIPY-phenylanthracene dyad for application in photodynamic therapy

Callaghan, S., Filatov, M. A., Savoie, H., Boyle, R.W. & Senge, M. O., A lead BODIPY-phenylanthracene dyad for application in photodynamic therapy, Proc. SPIE 11070, 17th International Photodynamic Association World Congress, 2019 11070, 110709I.

Over the past four years we have developed BODIPY dyads capable of triplet state generation from charge transfer states generated by photoinduced electron transfer. In the current work we identify a lead compound for application in photodynamic therapy. This system is composed of a phenylanthracene electron donor unit and a dimethyl-substituted BODIPY acceptor unit. We have demonstrated that this compound, in sub-micromolar concentrations, can effectively generate singlet oxygen in polar solvents and induce cytotoxicity in human breast cancer cells (MDA-MB-468) when exposed to light. The photophysical properties of these compounds are chemically tunable and thus open the door not only to a new class of photodynamic therapy photosensitizers, but also agents for triplet-triplet annihilation up-conversion applications.

https://dx.doi.org/10.1117/12.2525246

Synthesis of Porphyrinoids, BODIPYs, and (Dipyrrinato)ruthenium(II) Complexes from Prefunctionalized Dipyrromethanes

Hohlfeld, B.F., Flanagan, K. J., Kulak, N., Senge, M.O., Christmann, M. & Wiehe, A., Synthesis of Porphyrinoids, BODIPYs, and (Dipyrrinato)ruthenium(II) Complexes from Prefunctionalized Dipyrromethanes, Eur. J. Org. Chem, 2019, 2019, 25, 4020-4033.

The introduction of functional groups into the meso-position of dipyrromethanes, boron-dipyrromethenes (BODIPYs) and porphyrinoids, is of fundamental importance in designing such dye systems for material sciences or photomedicine. One route that has proven to be particularly useful in this respect is the nucleophilic aromatic substitution (SNAr) on porphyrinoids and their precursors carrying electron-withdrawing substituents. To further expand this methodology, the potential of the 4-fluoro-3-nitrophenyl and the 3,4,5-trifluorophenyl moieties for the synthesis of functionalized dipyrromethanes, BODIPYs, and porphyrinoids has been evaluated.

https://dx.doi.org/10.1002/ejoc.201900530

Controllable Charge-Transfer Mechanism at Push-Pull Porphyrin/Nanocarbon Interfaces.

ArpaÇay, P., Maity, P., El-Zohry, A. M., Meindl, A., Akca, S., Plunkett, S., Senge, M. O., Blau, W. J. and Mohammed, O. F., J. Phys. Chem. C 2019, 123, 23, 14283-14291.

Push-pull porphyrins are made of an electron donor (D), an electron acceptor (A), and a conjugated bridge connecting the D and A units. The tunability of their highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap can modulate their inter- and intramolecular charge-transfer (CT) and charge-separation (CS) characteristics and their reaction mechanism. Here, ultrafast charge transfer at the interfaces between 5,15-donor-acceptor push-pull porphyrins (Por-tBu and Por-OC8) and nanocarbon materials in the form of fullerene (C60) and graphene carboxylate (GC) are investigated using steady-state and pump-probe spectroscopic techniques.

https://dx.doi.org/10.1021/acs.jpcc.9b03718

Structure and conformation of photosynthetic pigments and related compounds. 15. Conformational analysis of chlorophyll derivatives-implications for hydroporphyrins in vivo

Gibbons, D., Flanagan, K. J., Pounot, L. & Senge, M.O., Structure and conformation of photosynthetic pigments and related compounds. 15. Conformational analysis of chlorophyll derivatives-implications for hydroporphyrins in vivo, Photochem. Photobiol. Sci., 2019, 18, 1479-1494.

Chlorophylls are fundamental macrocyclic cofactors in photosynthetic reaction centers and light-harvesting complexes. Their biological function is well understood on the basis of protein structural data and a significant ...

https://dx.doi.org/10.1039/C8PP00500A

Functionalization of Deutero- and Protoporphyrin IX Dimethyl Esters via Palladium-Catalyzed Coupling Reactions

O'Brien, J. M., Sitte, E., Flanagan, K. J., Kühner, H., Hallen, L. J., Gibbons, D. & Senge, M. O., Functionalization of Deutero- and Protoporphyrin IX Dimethyl Esters via Palladium-Catalyzed Coupling Reactions, J. Org. Chem. 2019, 84, 10, 6158-6173.

Herein, we report the functionalization of the ß-positions of deutero- and protoporphyrin IX dimethyl esters. Initial halogenations were carried out on both deutero- and protoporphyrin IX dimethyl esters. Although previously reported, vastly optimized yields with respect to deuteroporphyrin halogenation were obtained.

https://dx.doi.org/10.1021/acs.joc.9b00350

Not Your Usual Bioisostere: Solid State Study of 3D Interactions in Cubanes

Flanagan, K. J., Bernhard, S. S. R., Plunkett, S. & Senge, M. O., Not Your Usual Bioisostere: Solid State Study of 3D Interactions in Cubanes, Chem. Eur. J., 2019, 25, 28, 6941-6954.

Previous studies by Desiraju and co-workers have implicated the acidic hydrogen atoms of cubane as a support network for hydrogen bonding groups. Herein we report a detailed structural analysis of all currently available 1,4-disubstituted cubane structures with an emphasis on how the cubane scaffold interacts in its solid-state environment.

https://dx.doi.org/10.1002/chem.201806432

Highly Efficient One-Dimensional Triplet Exciton Transport in a Palladium-Porphyrin-Based Surface-Anchored Metal-Organic Framework

Adams, M., Kozlowska, M., Baroni, N., Oldenburg, M., Ma, R., Busko, D., Turshatov, A., Emandi, G., Senge, M.O., Haldar, R., Wöll, C., Nienhaus, G.U., Richards, B.S. & Howard, I.A., Highly Efficient One-Dimensional Triplet Exciton Transport in a Palladium-Porphyrin-Based Surface-Anchored Metal-Organic Framework, ACS Appl. Mater. Interfaces, 2019, 11, 17, 15688-15697.

Efficient photon-harvesting materials require easy-to-deposit materials exhibiting good absorption and excited-state transport properties. We demonstrate an organic thin-film material system, a palladium—porphyrin-based surface-anchored metal—organic framework (SURMOF) thin film that meets these requirements. Systematic investigations using transient absorption spectroscopy confirm that triplets are very mobile within single crystalline domains; a detailed analysis reveals a triplet transfer rate on the order of 1010 s-1. The crystalline nature of the SURMOFs also allows a thorough theoretical analysis using the density functional theory. The theoretical results reveal that the intermolecular exciton transfer can be described by a Dexter electron exchange mechanism that is considerably enhanced by virtual charge-transfer exciton intermediates.

https://dx.doi.org/10.1021/acsami.9b03079

Incremental Introduction of Organocatalytic Activity into Conformationally Engineered Porphyrins

Kielmann, M., Grover, N., Kalisch, W.W. & Senge, M.O., Incremental Introduction of Organocatalytic Activity into Conformationally Engineered Porphyrins, Eur. J. Org. Chem., 2019, 2019, 14, 2448-2452.

To study the correlation of macrocycle nonplanarity and catalytic activity of free base porphyrins in detail, a series of six tetraphenylporphyrins with graded degree of ß-ethyl substitution ("H2EtxTPPs" 1-6; x = 0, 2, 4, ...

https://dx.doi.org/10.1002/ejoc.201801691

Nonconjugated Hydrocarbons as Rigid-Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

Locke, G. M., Bernhard, S. S. R. and Senge, M. O., Nonconjugated Hydrocarbons as Rigid-Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry. Chem. Eur. J., 2019 25, 18, 4590-4647.

Nonconjugated hydrocarbons, like bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, triptycene, and cubane are a unique class of rigid linkers. Due to their similarity in size and shape they are useful mimics of classic benzene ...

https://dx.doi.org/10.1002/chem.201804225

Trendbericht Organische Chemie (Trends in Organic Chemistry)

Andexer, J. N., Beifuss, U., Beuerle, F., Brasholz, M., Breinbauer, R., Ernst, M., Gulder, T. A. M., Kath-Schorr, S., Kordes, M., Lehmann, M., Lindel, T., Lüdeke, S., Luy, B., Mantel, M., Mück-Lichtenfeld, C., Muhle-Goll, C., Narine, A., Niemeyer, J., Pfau, R., Pietruszka, J., Schaschke, N., Senge, M. O., Straub, B. F., Werner, T., Werz, D. B. and Winter, C., Organische Chemie., Nachr. Chem. 2019 66, 46—78.

Rekordwert bei der Umwandlung von Sonnenlicht in Tandemsolarzellen — längstes Acen — X-förmiges Porphyrintetramer — hochpotenter Influenza-Neuramidinidase-Inhibitor — Totalsynthese von Isoplagiochin D — chirales Phosphat zur stereoselektiven Katalyse — mechanochemische Direktsynthese einfacher Alkoxysilane aus Silicium und Alkoholen.

https://dx.doi.org/10.1002/nadc.20194085243

In vitro cytotoxicity of a library of BODIPYanthracene and -pyrene dyads for application in photodynamic therapy.

Callaghan, S.; Filatov, M. A.; Savoie, H.; Boyle, R. W.; Senge, M. O. In vitro cytotoxicity of a library of BODIPYanthracene and -pyrene dyads for application in photodynamic therapy. Photochem. Photobiol. Sci. 2019 18, 495—504.

The facile synthesis and in vitro activity of a library of heavy atom-free BODIPY-anthracene, -pyrene dyads (BAD-13—BPyrD-19) and a control (BODIPY 20) are reported. We demonstrate that singlet oxygen produced from dyad triplet states formed from charge-separated states is sufficient to induce cytotoxicity in human breast cancer cells (MDA-MB-468) at micromolar concentrations. The compounds in this series are promising candidates for photodynamic therapy, especially BAD-17 which displays significant photocytotoxicity (15% cell viability) at a concentration of 5 × 10—7 M, with minimal toxicity (89% cell viability) in the absence of light.

https://dx.doi.org/10.1039/C8PP00402A

The role of π–π stacking and hydrogen-bonding interactions in the assembly of a series of isostructural group IIB coordination compounds.

Hajiashrafi, T.; Zekriazadeh, R.; Flanagan, K. J.; Kia, F.; Bauzá, A.; Frontera, A.; Senge, M. O. The role of π–π stacking and hydrogen-bonding interactions in the assembly of a series of isostructural group IIB coordination compounds. Acta Cryst. 2019 C75, 178—188.

The supra­molecular chemistry of coordination compounds has become an im­portant research domain of modern inorganic chemistry. Herein, six iso­structural group IIB coordination compounds containing a 2-{[(2-meth­oxy­phen­yl)imino]­meth­yl}phenol ligand, namely di­chlorido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­niumyl­idene]meth­yl}pheno­lato-κO)zinc(II), [ZnCl2(C28H26N2O4)], 1, di­iodido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­niumyl­idene]meth­yl}pheno­lato-κO)zinc(II), [ZnI2(C28H26N2O4)], 2, di­bromido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­n­iumyl­idene]meth­yl}pheno­lato-κO)cadmium(II), [CdBr2(C28H26N2O4)], 3, di­iodido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­niumyl­idene]meth­yl}pheno­lato-κO)cadmium(II), [CdI2(C28H26N2O4)], 4, di­chlorido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­niumyl­idene]meth­yl}pheno­lato-κO)mercury(II), [HgCl2(C28H26N2O4)], 5, and di­iodido­bis­(2-{(E)-[(2-meth­oxy­phen­yl)aza­niumyl­idene]meth­yl}pheno­lato-κO)mercury(II), [HgI2(C28H26N2O4)], 6, were synthesized and characterized by X-ray crystallography and spectroscopic techniques. All six compounds exhibit an infinite one-dimensional ladder in the solid state governed by the formation of hydrogen-bonding and π–π stacking inter­actions. The crystal structures of these compounds were studied using geometrical and Hirshfeld surface analyses. They have also been studied using M06-2X/def2-TZVP calculations and Bader's theory of `atoms in mol­ecules'. The energies associated with the inter­actions, including the contribution of the different forces, have been evaluated. In general, the π–π stacking inter­actions are stronger than those reported for conventional π–π complexes, which is attributed to the influence of the metal coordination, which is stronger for Zn than either Cd or Hg. The results reported herein might be useful for understanding the solid-state architecture of metal-containing materials that contain MIIX2 subunits and aromatic organic ligands.

https://dx.doi.org/10.1107/S2053229618018314

Molekulares Engineering freier Porphyrinbasen als Liganden — das N-H⋯X-Bindungsmotiv in Tetrapyrrolen.

Kielmann, M.; Senge, M. O. Molekulares Engineering freier Porphyrinbasen als Liganden - das N-H⋯X-Bindungsmotiv in Tetrapyrrolen. Angew. Chem. 2019, 131, 2, 424-448.

Die N-H-Einheiten im Kern planarer Porphyrine sind oft nicht zugänglich, um Wasserstoffbrückenkomplexe mit Akzeptormolekülen zu bilden. Dies liegt daran, dass die funktionellen Aminogruppen durch das makrozyklische System abgeschirmt sind, was die Bildung intermolekularer H-Brücken hemmt.

https://dx.doi.org/10.1002/ange.201806281

Molecular Engineering of Free-Base Porphyrins as Ligands—The N-H⋯X Binding Motif in Tetrapyrroles.

Kielmann, M.; Senge, M. O. Molecular Engineering of Free-Base Porphyrins as Ligands - The N-H⋯X Binding Motif in Tetrapyrroles. Angew. Chem. Int. Ed. 2019, 58, 418—441.

The core N—H units of planar porphyrins are often inaccessible to forming hydrogen-bonding complexes with acceptor molecules. This is due to the fact that the amine moieties are ″shielded″ by the macrocyclic system, impeding the formation of intermolecular H-bonds. However, methods exist to modulate the tetrapyrrole conformations and to reshape the vector of N—H orientation outwards, thus increasing their availability and reactivity. Strategies include the use of porpho(di)methenes and phlorins (calixphyrins), as well as saddle-distorted porphyrins. The former form cavities due to interruption of the aromatic system. The latter are highly basic systems and capable of binding anions and neutral molecules via N—H ⋯X-type H-bonds. This Review discusses the role of porphyrin(oid) ligands in various coordination-type complexes, means to access the core for hydrogen bonding, the concept of conformational control, and emerging applications, such as organocatalysis and sensors.

https://dx.doi.org/10.1002/anie.201806281

Nonplanar Porphyrins by N-Substitution: A Neglected Pathway.

Roucan, M.; Flanagan, K. J.; O′Brien J.; Senge, M. O. Nonplanar Porphyrins by N-Substitution: A Neglected Pathway. Eur. J. Org. Chem., 2018, 6432 - 6446.

N -substitution of porphyrins has been a neglected route towards nonplanar porphyrins for the past decades. Previously, they featured in a host of potential medicinal and biochemical applications. However, tailored syntheses of N -methylated porphyrins, improvements of synthetic methodology, or full conformational analyses were lacking since the initial studies. Here we investigated and optimized synthetic pathways to generate specific N -methylated porphyrins exclusively and in good yields. Full characterizations of the spectroscopy and structural properties associated with the insertion of different numbers of methyl into the porphyrin core of 5,10,15,20-tetrasubstituted A4- and 5,15-disubstituted A2-type porphyrins was carried out by using UV/Vis, NMR, and X-ray crystallographic techniques. The latter, in conjunction with detailed normal structural decomposition analyses, identified the structural consequences of number and isomeric pattern of N -methylation in terms of macrocycle nonplanarity and the underlying out-of-plane and in-plane distortion modes.

https://dx.doi.org/10.1002/ejoc.201800960

Reaction of porphyrin-based surface-anchored metal—organic frameworks caused by prolonged illumination.

Adams, M.; Baroni, N.; Oldenburg, M.; Kraffert, F.; Behrends, J.; McQueen, R. W.; Haldar, R.; Busko, D.; Turshatov, A.; Emandi, G.; Senge, M. O.; Wöll, C.; Lips, K.; Richards, B. S.; Howard, I. A. Reaction of porphyrin-based surface-anchored metal—organic frameworks caused by prolonged illumination. Phys. Chem. Chem. Phys., 2018, 20, 29142-29151

Crystalline surface-anchored metal—organic framework (SURMOF) thin films made from porphyrin-based organic linkers have recently been used in both photon upconversion and photovoltaic applications. While these studies showed promising results, the question of photostability in this organic—inorganic hybrid material has to be investigated before applications can be considered. Here, we combine steady-state photoluminescence, transient absorption, and time-resolved electron paramagnetic resonance spectroscopy to examine the effects of prolonged illumination on a palladium-porphyrin based SURMOF thin film. We find that phototreatment leads to a change in the material's photoresponse caused by the creation of stable products of photodecomposition — likely chlorin — inside the SURMOF structure. When the mobile triplet excitons encounter such a defect site, a short-lived (80 ns) cation—anion radical pair can be formed by electron transfer, wherein the charges are localized at a porphyrin and the photoproduct site, respectively.

https://dx.doi.org/10.1039/C8CP05254A

The good, the bad, and the ugly — controlling singlet oxygen through design of photosensitizers and delivery systems for photodynamic therapy.

Callaghan, S.; Senge, M. O. The good, the bad, and the ugly — controlling singlet oxygen through design of photosensitizers and delivery systems for photodynamic therapy. Photochem. Photobiol. Sci. 2018, 17, 1490—1514.

Singlet oxygen, although integral to photodynamic therapy, is notoriously uncontrollable, suffers from poor selectivity and has fast decomposition rates in biological media. Across the scientific community, there is a conscious effort to refine singlet oxygen interactions and initiate selective and controlled release to produce a consistent and reproducible therapeutic effect in target tissue. This perspective aims to provide an insight into the contemporary design principles behind photosensitizers and drug delivery systems that depend on a singlet oxygen response or controlled release. The discussion will be accompanied by in vitro and in vivo examples, in an attempt to highlight advancements in the field and future prospects for the more widespread application of photodynamic therapy.

https://dx.doi.org/10.1039/C8PP00008E

Synthesis of amphiphilic meso-tetrasubstituted porphyrin-L-amino acid and -heterocyclic conjugates based on m-THPP.

Sweet, A. M. K.; Senge, M. O.; Atta S. M. Sh.; Farrag, D. S.; Abdel-Rahman, A.-R. H.; Shaker, Y. M. Synthesis of amphiphilic meso-tetrasubstituted porphyrin-L-amino acid and -heterocyclic conjugates based on m-THPP. J. Porphyr. Phthalocya. 2018, 22, 997—1009.

Two series of amphiphilic meso-tetrasubstituted porphyrin conjugates based on 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (m-THPP) covalently linked to L-amino acids and heterocycles were synthesized efficiently in the context of a program targeting new photosensitizers for PDT. 5,10,15-Tris(3-hydroxyphenyl)-20-(3-oxyacetic acid)phenyl]porphyrin and the respective trihexyl ether derivatives were conjugated with polar and non-polar natural L-amino acids such as glycine, L-proline, and L-tyrosine via an amide bond linker using N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate in diisopropylethylamine (HBTU/DIPEA).

https://dx.doi.org/10.1142/S1088424618500979

Fluorescent imidazole-based chemosensors for the reversible detection of cyanide and mercury ions.

Emandi, G.; Flanagan, K. J.; Senge, M. O. Fluorescent imidazole-based chemosensors for the reversible detection of cyanide and mercury ions. Photochem. Photobiol. Sci. 2018, 17, 1450—1461.

We report 4-(2-(5-(tert-butyl)-3-formyl-2-hydroxyphenyl)-1H-phenanthro[9,10-d]imidazol-1-yl)benzoic acid 1 and 4-(2-(5-(tert-butyl)-3-formyl-2-hydroxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)benzoic acid 2 as reversible luminescent sensors for the detection of cyanide and mercury ions. These imidazole derivatives were characterized using spectroscopic techniques and single crystal X-ray crystallography. The compounds showed sensing exclusively towards CN— ions, which resulted in the quenching of fluorescence and a decreased singlet state life time.

https://dx.doi.org/10.1039/c8pp00226f

Crystal structure and synthesis of 3-(1H-pyrrol-2-yl)-1-(thiophen-2-yl)propanone

Gibbons, D., Emandi, G.and Senge, M. O., Crystal structure and synthesis of 3-(1H-pyrrol-2-yl)-1-(thiophen-2-yl)propanone, Acta Cryst. 2018, E74, 1463—1466.

The title compound, C11H9NOS, was obtained in an improved yield compared to previous literature methods. The molecule is essentially planar with a maximum deviation of 0.085ߕÅ from the mean plane through all non-H atoms. There is directive intermolecular hydrogen bonding in the form of N—Hef;O hydrogen bonds with a distance of 2.889ߕ(3)ߕÅ between the pyrrole amine and the ketone carbonyl O atom. The resulting hydrogen-bonding network defines a ribbon parallel to the a axis. These ribbons form offset stacks along the b axis.

https://dx.doi.org/10.1107/S2056989018012331

Pre-/post-functionalization in dipyrrin metal complexes — antitumor and antibacterial activity of their glycosylated derivatives

Gutsche, C. S., Gräfe, S., Gitter, B., Flanagan, K. J., Senge, M. O., Kulak, N. and Wiehe, A., Pre-/post-functionalization in dipyrrin metal complexes — antitumor and antibacterial activity of their glycosylated derivatives, Dalton Trans., 2018, 47, 12373-12384

A post-functionalization route to tris(dipyrrinato) metal complexes is presented giving access to a range of new complexes relevant in the context of medicinal inorganic chemistry. A pentafluorophenyl group in the meso-position of the dipyrrin ligand serves as an anchor for the connection with alcohols and thiocarbohydrates. The photochemotherapeutic activity of the complexes has been assessed in cellular assays with tumor cell lines and against the Gram-positive bacterium S. aureus. Finally, it is shown that this post-functionalization is also applicable to other dipyrrinato metal complexes.

https://dx.doi.org/10.1039/C8DT03059F

BODIPY-Pyrene and Perylene Dyads as Heavy-Atom-Free Singlet Oxygen Sensitizers

Filatov, M. A., Karuthedath, S., Polestshuk, P. M., Callaghan, S., Flanagan, K. J., Wiesner, T., Laqaui, F. and Senge, M. O., BODIPY-Pyrene and Perylene Dyads as Heavy-Atom-Free Singlet Oxygen Sensitizer, ChemPhotoChem 2018, 2, 606 —615

Dyads combining BODIPY as an electron acceptor and pyrene or perylene as electron donor subunits were prepared and their photophysical properties were studied by steady-state and transient spectroscopy. Depending on the structure of the subunits and the polarity of the media, the dyads show either bright fluorescence or photo-induced electron transfer (PeT) in solution. Charge-transfer (CT) states formed as a result of PeT and were found to yield triplet excited states of the BODIPY. In the presence of molecular oxygen, the dyads sensitize singlet oxygen (1O2) with quantum yields of up to 0.75.

https://dx.doi.org/10.1002/cptc.201800020

Synthesis and Characterization of Temperature-Sensitive and Chemically Cross-Linked Poly(N-isopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy

Belali, S., Savoie, H., O′Brien, J. M., Cafolla, A. A., O′Connell, B., Karimi, A. R., Boyle, R. W. and Senge, M. O., Synthesis and Characterization of Temperature-Sensitive and Chemically Cross-Linked Poly(Nߛisopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy, Biomacromolecules 2018, 19, 1592—1601.

A novel poly(N-isopropylacrylamide) (PNIPAM) hydrogel containing different photosensitizers (protoporphyrin IX (PpIX), pheophorbide a (Pba), and protoporphyrin IX dimethyl ester (PpIX-DME)) has been synthesized with a significant improvement in water solubility and potential for PDT applications compared to the individual photosensitizers (PSs). Conjugation of PpIX, Pba, and PpIX-DME to the poly(N-isopropylacrylamide) chain was achieved using the dispersion polymerization method. This study describes how the use of nanohydrogel structures to deliver a photosensitizer with low water solubility and high aggregation tendencies in polar solvents overcomes these limitations. FT-IR spectroscopy, UV—vis spectroscopy, 1H NMR, fluorescence spectroscopy, SEM, and DLS analysis were used to characterize the PNIPAM—photosensitizer nanohydrogels. Spectroscopic studies indicate that the PpIX, Pba, and PpIX-DME photosensitizers are covalently conjugated to the polymer chains, which prevents aggregation and thus allows significant singlet oxygen production upon illumination. Likewise, the lower critical solution temperature was raised to ∼44 °C in the new PNIPAM-PS hydrogels. The PNIPAM hydrogels are biocompatible with >90% cell viability even at high concentrations of the photosensitizer in vitro. Furthermore, a very sharp onset of light-dependent toxicity for the PpIX-based nanohydrogel in the nanomolar range and a more modest, but significant, photocytotoxic response for Pba-PNIPAM and PpIX-DME-PNIPAM nanohydrogels suggest that the new hydrogels have potential for applications in photodynamic therapy.

https://dx.doi.org/10.1021/acs.biomac.8b00293

Porphyrins in troubled times: a spotlight on porphyrins and their metal complexes for explosives testing and CBRN defense

Kielmann, M., Prior, C., and Senge, M. O., Porphyrins in troubled times: a spotlight on porphyrins and their metal complexes for explosives testing and CBRN defense, New J. Chem., 2018, 42, 7529-7550.

Porphyrins are large Π-aromatic systems that can complex metal ions from all across the periodic table. The resulting metalloporphyrins are readily tunable with regards to analyte detection properties, and constitute an important class of chemical sensors. In light of the current geopolitical situation and security concerns, we review the potential of porphyrins and their metal complexes for the detection of explosives and their use in chemical, biological, radiological and nuclear (CBRN) defense and set them in the context of up-and-coming security-related applications.

https://dx.doi.org/10.1039/C7NJ04679K

Enhancing the photoluminescence of surface anchored metal—organic frameworks: mixed linkers and efficient acceptors

Oldenburg, M., Turshatov, A., Busko, D., Jakovy, M., Haldar, R., Chen, K., Emandi, G., Senge, M. O., Wöll, C., Hodgkiss, J. M., Richards, B. S., and Howard, I. A., Enhancing the photoluminescence of surface anchored metal—organic frameworks: mixed linkers and efficient acceptors, Phys. Chem. Chem. Phys., 2018, 20, 11564-11576.

We present two approaches to enhance the photoluminescence quantum yield (PLQY) of surface-anchored metal—organic frameworks (SURMOFs). In the first approach we fabricate SURMOFs from a mix of an emissive linker with an optically-inert linker of equivalent length, diluting the emissive linker while maintaining the SURMOF structure. This approach enhances the internal PLQY. However, the increase in internal PLQY is achieved at the expense of a drastic reduction in optical absorption, thus the external PLQY remains low. To overcome this limitation, a second approach is explored wherein energy-accepting guest chromophores are infiltrated into the framework of the active linker. At the correct acceptor concentration, an internal PLQY of 52% — three times higher than the previous approach — is achieved. Additionally, the absorption remains strong leading to an external PLQY of 8%, an order of magnitude better than the previous approach. Using this strategy, we demonstrate that SURMOFs can achieve PLQYs similar to their precursor chromophores in solution. This is of relevance to SURMOFs as emitter layers in general, and we examine the optimized emitter layer as part of a photon upconversion (UC) SURMOF heterostructure. Surprisingly, the same PLQY is not observed after triplet—triplet annihilation in the UC heterostructure as after its normal photoexcitation (although the UC layers exhibit low thresholds consistent with those reported in our previous work). We discuss the potential bottlenecks in energy transport that could lead to this unexpected reduction in PLQY after excitation via triplet—triplet annihilation, and how future design of SURMOF UC multilayers could overcome these limitations.

https://dx.doi.org/10.1039/C7CP08452H

Control of triplet state generation in heavy atom-free BODIPY—anthracene dyads by media polarity and structural factors

Filatov, M. A., Karuthedath, S., Polestshuk, P. M., Callaghan, S., Flanagan, K. J., Telitchko, M., Wiesner, T., Laquai, F., Senge, M. O., Control of triplet state generation in heavy atom-free BODIPY—anthracene dyads by media polarity and structural factors, Phys. Chem. Chem. Phys. 2018, 20, 8016—8031.

A family of heavy atom-free BODIPY—anthracene dyads (BADs) exhibiting triplet excited state formation from charge-transfer states is reported. Four types of BODIPY scaffolds, different in the alkyl substitution pattern, and four anthracene derivatives have been used to access BADs. Fluorescence and intersystem crossing (ISC) in these dyads depend on donor—acceptor couplings and can be accurately controlled by substitution or media polarity. Under conditions that do not allow charge transfer (CT), the dyads exhibit fluorescence with high quantum yields. Formation of charge-transfer states triggers ISC and the formation of long-lived triplet excited states in the dyads. The excited state properties were studied by steady-state techniques and ultrafast pump—probe spectroscopy to determine the parameters of the observed processes. Structural information for various BADs was derived from single crystal X-ray structure determinations alongside DFT molecular geometry optimization, revealing the effects of mutual orientation of subunits on the photophysical properties. The calculations showed that alkyl substituents on the BODIPY destabilize CT states in the dyads, thus controlling the charge transfer between the subunits. The effect of the dyad structure on the ISC efficiency was considered at the M06-2X level of theory, and a correlation between mutual orientation of the subunits and the energy gap between singlet and triplet CT states was studied using a multireference CAßCF method.

https://dx.doi.org/10.1039/C7CP08472B

Sterically induced distortions of nickel(II) porphyrins — Comprehensive investigation by DFT calculations and resonance Raman spectroscopy

Schindler, J., Kupfer, S., Ryan, A. A., Flanagan, K. J., Dietzek, B., Senge, M. O., Sterically induced distortions of nickel(II) porphyrins — Comprehensive investigation by DFT calculations and resonance Raman spectroscopy, Coord. Chem. Rev. 2018, 360, 1—16.

A series of 5,15-disubstituted and 5,10,15,20-tetrasubstituted, and 5,10,15,20-tetrasubstituted-2,3,7,8,12,13,17,18-octaethyl nickel(II) porphyrins in dichloromethane is reported to comprehensively access their sterically induced distortions from planarity. Thus, the tutorial review focuses on both resonance Raman spectroscopic investigations and structural investigations based on DFT. We relate different theoretical and experimental methodologies to predict out-of-plane distortions of the porphyrin macrocycles which are quantified by normal-coordinate structural decomposition. This comprehensive compilation reveals shortcomings in the molecular mechanic calculations and illustrates the impact of crystal packing forces on crystal structures. Non-planar distortions shift the experimentally observed resonance Raman marker bands Ν2, Ν3 and Ν4 to lower frequency. A revised correlation between this shift and the calculated structural parameter (ruffling angle) is presented and reveals deviations from reported correlations based on molecular mechanics.

https://dx.doi.org/10.1016/j.ccr.2017.12.014

Organic Chemistry Trend Report 2017

Straub, B., Andexer, J. N., Arenz, C., Beifuss, U., Beuerle, F., Brasholz, M., Breinbauer, R., Ditrich, K., Ernst, M., Gulder, T. A. M., Kordes, M., Krueger, A., Lehmann, M., Lindel, T., Lüdeke, S., Luy, B., Meier, M. A. R., Mück-Lichtenfeld, C., Muhle-Goll, C., Narine, A., Paradies, J., Pfau, R., Pietruszka, J., Schaschke, N., Senge, M. O., Werner, T., Werz, D. B., Winter, C., Worgull, D., Nachr. Chem. 2018, 66, 249—280.

Molecular node with topological chirality - structure elucidation of the polyol macrolide deplelid A - total synthesis of crocagin A - organocatalysis in supramolecular aggregates - sustainable oxidation on oxymorphone - iron-catalyzed enantioselective C — H activation and alkylation - fluorescent artificial DNA base pair

https://dx.doi.org/10.1002/nadc.20184072148

The Janus-faced chromophore: a donor—acceptor dyad with dual performance in photon up-conversion

Kiseleva, N., Filatov, M. A., Oldenburg, M., Busko, D., Jakoby, M., Howard, I. A., Richards, B. S., Senge, M. O., Borisov, S. M., Turshatov, A., The Janus-faced chromophore: a donor—acceptor dyad with dual performance in photon up-conversion, Chem. Commun., 2018, 54, 1607-1610.

An electron donor—acceptor dyad based on BODIPY (acceptor) and anthracene (donor) plays either the role of sensitizer or emitter in triplet—triplet annihilation photon up-conversion (TTA-UC). This Janus-like behavior was achieved via altering the relative ordering of charge-transfer and local excited state energies in the dyad through the polarity of TTA-UC media.

https://dx.doi.org/10.1039/C7CC08930A

Cubane Cross-Coupling and Cubane—Porphyrin Arrays

Bernhard, S. S. R., Locke, G. M., Plunkett, S., Meindl, A., Flanagan, K. J., Senge, M. O., Cubane Cross-Coupling and Cubane-Porphyrin Arrays.Chem. Eur. J. 2018, 24, 1026—1030.

Herein, an improved methodology for aryl-cubane cross-coupling is reported. The peculiarities of the cubane core and its behavior during cross-coupling conditions were analyzed, while the versatility of this adapted Baran cross-coupling methodology was demonstrated by the synthesis of various aryl-cubane systems, including coupling products of cubanes and porphyrins. Furthermore, arm extension of alkynyl-cubanes by Sonogashira reactions is demonstrated, showcasing the first proof of the stability of the cubane core in the presence of palladium catalysts.

https://dx.doi.org/10.1002/chem.201704344

Conformational control of nonplanar free base porphyrins: towards bifunctional catalysts of tunable basicity

Roucan, M., Kielmann, M., Connon, S. J., Bernhard, S. S. R., Senge, M. O., Conformational control of nonplanar free base porphyrins: towards bifunctional catalysts of tunable basicity, Chem. Commun., 2018, 54, 26-29.

For the first time, free base and N-methylated porphyrins have been utilized as bifunctional organocatalysts in Michael additions and it was found that distortion of the macrocycle is a vital prerequisite for their catalytic activity. Conformational design has been used to tailor the properties of nonplanar porphyrins with regards to availability of the N—H units for hydrogen bonding (distortion-dependent hydrogen bonding) and the basicity of the heterocyclic groups. NMR spectroscopic- and catalyst screening studies provided insight into the likely mode of catalyst action. This unprecedented use of free base and N-substituted porphyrins as organocatalysts opens a new functional role for porphyrins.

https://dx.doi.org/10.1039/C7CC08099A

Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic

Khan, M. S. J., Wang, Y.-W., Senge, M. O., Peng, Y., Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic, J. Hazard. Mater. 2018, 342, 10—19.

Two highly sensitive probes bearing a nucleophilic imine moiety have been utilized for the selective detection of chemical warfare agent (CWA) mimics. Diethyl chlorophosphate (DCP) was used as mimic CWAs. Both iminocoumarin-benzothiazole-based probes not only demonstrated a remarkable fluorescence ON-OFF response and good recognition, but also exhibited fast response times (10 s) along with color changes upon addition of DCP. Limits of detection for the two sensors 1 and 2 were calculated as 0.065 ΜM and 0.21 ΜM, respectively, which are much lower than most other reported probes. These two probes not only show high sensitivity and selectivity in solution, but can also be applied for the recognition of DCP in the gas state, with significant color changes easily observed by the naked eye.

https://dx.doi.org/10.1016/j.jhazmat.2017.08.009

Merging Triptycene, BODIPY and Porphyrin Chemistry: Synthesis and Properties of Mono- and Trisubstituted Triptycene Dye Arrays

Emandi, G., Shaker, Y. M., Flanagan, K. J., O′Brien, J. M., Senge, M. O., Merging Triptycene, BODIPY and Porphyrin Chemistry: Synthesis and Properties of Mono- and Trisubstituted Triptycene Dye Arrays, Eur. J. Org. Chem. 2017, 6680—6692.

A series of functionalized triptycene scaffolds has been synthesized using 2-formyltriptycene and 5-(2-triptycenyl)dipyrromethane. Using these two key precursors, mixed condensations with different aromatic aldehydes and aryl-dipyrromethanes gave access to all members of triptycenyl meso -substituted porphyrins (AB3-, A2B2-, A3B-, and A4) and allowed their photophysical and electrochemical characterization. Additionally, the first crystal structure of tetratriptycenylporphyrin is reported. 2-Formyltriptycene was also used for the preparation of two different mono-BODIPY-triptycene compounds, while 2,6,14-triiodotriptycene was used in Suzuki and Sonogashira cross-coupling reactions to obtain threefold BODIPY-substituted triptycene—dye conjugates. The mono- and tri-BODIPY-substituted triptycene scaffolds exhibit good absorption in the visible to NIR region indicating the potential use of the triptycene scaffold as the core of multi-dye light-harvesting systems.

https://dx.doi.org/10.1002/ejoc.201701206

Water-soluble, neutral 3,5-diformyl-BODIPY with extended fluorescence lifetime in a self-healable chitosan hydrogel

Belali, S., Emandi, G., Cafolla, A. A., O′Connell, B., Haffner, B., Möbius, M. E., Karimi, A., Senge, M. O., Water-soluble, neutral 3,5-diformyl-BODIPY with extended fluorescence lifetime in a self-healable chitosan hydrogel, Photochem. Photobiol. Sci., 2017, 16, 1700-1708.

3,5-Diformyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (3,5-diformyl-BODIPY) can be used as an efficient biofunctional cross-linker to generate a new class of chitosan-based hydrogels with fluorescence resonance energy transfer (FRET) dynamics and good solubility in water. The hydrogel was fully characterized by FT-IR, UV-vis, fluorescence, FE-SEM, AFM, rheology and picosecond time-resolved spectroscopic techniques. The self-healing ability was demonstrated by rheological recovery and macroscopic and microscopic observations. The fluorescence lifetime was found to increase in aqueous solution of the BODIPY-chitosan hydrogel compared to the 3,5-diformyl-BODIPY monomer. Calculations based on experimental results such as red-shift and decreased intensity of the emission spectrum of highly dye-concentrated hydrogel in comparison to dilute hydrogels, together with changes in the fluorescence lifetime of the hydrogel at different concentration of dyes, suggest that the BDP-CS hydrogels fluorescence dynamics obey the Förster resonance energy transfer (FRET). Improvements in mechanical and photochemical properties and the acceptable values of BODIPY fluorescence lifetime in the hydrogel matrix indicate the utility of the newly synthesized hydrogels for biomedical applications.

https://dx.doi.org/10.1039/C7PP00316A

Lactones and Flavonoids isolated from the Leaves of Globimetula braunii

Ja′afar, M. K.; Jamill, S.; Basar, N.; Bakar, M. B.; Sarker, S. D.; Flanagan, K. J.; Senge, M. O., Lactones and Flavonoids isolated from the Leaves of Globimetula braunii, Nat. Prod. Commun. 2017, 12, 1455—1458.

The dried powdered leaves of Globimetula braunii (Engler) Van Tiegh were effectively extracted by the cold extraction method. Purification of the EtOAc-soluble and MeOH-soluble extracts successfully yielded two lactones namely (R)-6-[(S)-2-hydroxy-4-(4-hydroxyphenyl)butyl]—5,6-dihydropyran-2-one (dodoneine) 1 and (1R,5S,7S)-[2-(4-hydroxyphenyl)ethyl]-2,6-dioxabicyclo[3.3.1]-nonan-3-one (2), together with five flavonoids namely quercetin 3, (+)-catechin 4, quercitrin 5, rutin 6 and avicularin 7. Their structures were established by spectroscopic means, and the absolute configuration of compound 1 was confirmed by X-ray analysis.

https://dx.doi.org/10.1177/1934578X1701200918

Delayed release singlet oxygen sensitizers based on pyridone-appended porphyrins

Callaghan, S., Filatov, M. A., Sitte, E., Savoie, H., Boyle, R. W., Flanagan, K. J., Senge, M. O., Delayed release singlet oxygen sensitizers based on pyridone-appended porphyrins, Photochem. Photobiol. Sci., 2017, 16, 1371—1374

A new type of porphyrin photosensitizer capable of generating singlet oxygen upon irradiation, storing it through binding to pyridone subunits, followed by slow release at 20—40 °C, is reported. The timescale of singlet oxygen release can be varied depending on the pyridone group substitution pattern, forming endoperoxides of different stabilities. Modified tetra- and octa-substituted pyridone-porphyrins showed solubility in water, allowing for straightforward delivery into cells. The effect of delayed singlet oxygen formation due to endoperoxide decomposition was demonstrated on cancer cells in vitro.

https://dx.doi.org/10.1039/C7PP00244K

Synthesis of Long-Wavelength Absorbing Porphyrin m-Benzoic Acids as Molecular Tectons for Surface Studies

Meindl, A., Ryan, A. A., Flanagan, K. J., Senge, M. O., Synthesis of Long-Wavelength Absorbing Porphyrin m-Benzoic Acids as Molecular Tectons for Surface Studies, Heterocycles 2017, 94, 1518—1541.

Porphyrins are becoming increasingly important building blocks in material science. This is due in part to several favorable characteristics; such as strong absorption into the infrared region, tunable electronic properties and the possibility to modify and define the porphyrin core in multiple ways. Herein we report synthetic methodologies for porphyrin-based molecular tectons for surface studies. The study aims to generate porphyrins with directional anchoring groups of different length and we report a library of long-wavelength absorbing porphyrins with a special focus on organometallic coupling reactions for the introduction of benzoic acid moieties as anchor groups.

https://dx.doi.org/10.3987/COM-17-13744

Comparative Synthetic Strategies for the Generation of 5,10- and 5,15-Substituted Push-Pull Porphyrins

Meindl, A., Plunkett, S., Ryan, A. A., Flanagan, K. J., Callaghan, S., Senge, M. O., Comparative Synthetic Strategies for the Generation of 5,10- and 5,15-Substituted Push-Pull Porphyrins, Eur. J. Org. Chem. 2017, 3565—3583.

Contemporary applications in optics, medicine, solar cells, or material science are increasingly reliant on unsymmetrically substituted porphyrins. Due to their widespread applications and rise in demand we undertook a comparative analysis of synthetic strategies for meso -substituted porphyrins and present the synthesis of five different series of so-called A2BC push-pull porphyrins. The synthetic pathways used were applied to both 5,15-substituted and 5,10-substituted porphyrins, showcasing their flexibility and adaptability for different needs. Our approach combines well-known reactions with a strategic and logical stepwise functionalization allowing researchers to change and modify the electronic properties of these systems at various points of the syntheses. This facilitates the easy optimization of the synthesis of systems of current interest, for example, porphyrins for dye-sensitized solar cells (DßCs) or for use in nonlinear optics, as well as fast generation of compound libraries.

https://dx.doi.org/10.1002/ejoc.201700093

Sequential Nucleophilic Substitution of the Α-Pyrrole and p -Aryl Positions of meso -Pentafluorophenyl-Substituted BODIPYs

Gutsche, C. S., Hohlfeld, B. F., Flanagan, K. J., Senge, M. O., Kulak, N., Wiehe, A., Sequential Nucleophilic Substitution of the Α-Pyrrole and p-Aryl Positions of meso-Pentafluorophenyl-Substituted BODIPYs, Eur. J. Org. Chem. 2017, 3187—3196

Boron—dipyrrins (BODIPYs) have found widespread application in bioimaging and materials science. These applications require the tuning of the chemical and photophysical properties of the fluorophore through the introduction of functional groups at the BODIPY core. In this context, an approach to difunctionalized BODIPYs was explored. Oxidative nucleophilic substitution of hydrogen (ONSH) in the 3-(Α-)position of the BODIPYs was combined with nucleophilic substitution (SNAr) at the aryl unit of pentafluorophenyl-substituted BODIPYs and their dipyrrane precursors. In an alternative approach, Α-alkoxy-substituted BODIPYs were prepared starting from the corresponding dipyrrin. In this case, the Α-methoxy group of the BODIPY was susceptible to a hitherto unreported methoxy/amino exchange. The compounds were investigated with respect to their optical spectroscopic properties, revealing the influence of the different substitution patterns on their absorption and emission spectra.

https://dx.doi.org/10.1002/ejoc.201700264

Synthesis of a Family of Highly Substituted Porphyrin Thioethers via Nitro Displacement in 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin

Kielmann, M., Flanagan, K. J., Norvaiša, K., Intrieri, D., Senge, M. O., Synthesis of a Family of Highly Substituted Porphyrin Thioethers via Nitro Displacement in 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyri, J. Org. Chem. 2017, 82, 5122—5134.

A series of highly substituted porphyrin thioethers was synthesized from 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetranitroporphyrin (H2OETNP). The reactions proceeded via a SNAr mechanism with a broad range of aromatic thiols in the presence of a base. This is a rapid way to prepare a large variety of meso-substituted porphyrins from only one precursor. Single crystal X-ray analysis revealed that these new porphyrin thioethers are highly distorted, exhibiting conformational properties that are distinctive of both meso-sulfur substitution and steric overcrowding in general. Additionally, denitration of H2OETNP under basic conditions was investigated, yielding products of stepwise desubstitution. This allowed a comparative X-ray crystallographic study to delineate the successive structural effects of an increasing degree of nitro substitution in the complete series of nitro-substituted octaethylporphyrins.

https://dx.doi.org/10.1021/acs.joc.7b00328

Generation of Triplet Excited States via Photoinduced Electron Transfer in meso-anthra-BODIPY: Fluorogenic Response toward Singlet Oxygen in Solution and in Vitro

Filatov, M. A., Karuthedath, S., Polestshuk, P. M., Savoie, H., Flanagan, K. J., Sy, C., Sitte, E., Telitchko, M., Laquai, F., Boyle R. W., Senge, M. O., Generation of Triplet Excited States via Photoinduced Electron Transfer in meso-anthra-BODIPY: Fluorogenic Response toward Singlet Oxygen in Solution and in Vitro, J. Am. Chem. Soc. 2017, 139, 6282—6285.

Heavy atom-free BODIPY-anthracene dyads (BADs) generate locally excited triplet states by way of photoinduced electron transfer (PeT), followed by recombination of the resulting charge-separated states (Cß). Subsequent quenching of the triplet states by molecular oxygen produces singlet oxygen (1O2), which reacts with the anthracene moiety yielding highly fluorescent species. The steric demand of the alkyl substituents in the BODIPY subunit defines the site of 1O2 addition. Novel bis- and tetraepoxides and bicyclic acetal products, arising from rearrangements of anthracene endoperoxides were isolated and characterized. 1O2 generation by BADs in living cells enables visualization of the dyads distribution, promising new imaging applications.

https://dx.doi.org/10.1021/jacs.7b00551

Sustainable water treatment in aquaculture — photolysis and photodynamic therapy for the inactivation of Vibrio species

Malara, D.; Mielke, C.; Oelgemöller, M; Senge, M. O.; Heimann, K., Sustainable water treatment in aquaculture — Photolysis and photodynamic therapy for the inactivation of Vibrio species. Aquac. Res. 2017, 48, 2954—2962.

Species of the genus Vibrio have been recognized as one of the most significant pathogens in aquaculture farming, causing mass mortality of farmed stocks. Photodynamic Antimicrobial Chemotherapy (PACT ) with singlet oxygen (1O2) has been identified as a powerful and sustainable water treatment method for pathogen eradication. In this study, the efficiencies of photolytic and photodynamic disinfection protocols were studied with two Vibrio species, Vibrio parahaemolyticus and Vibrio owensii . The selected microorganisms were successfully cultivated in marine broth and irradiations were performed with ~108 bacteria mL —1. Treated samples were monitored for bacterial regrowth for up to 7 days. Photolysis experiments were initially conducted with UV -A, UV -B for up to 2 h and visible (VIS ) light for up to 24 h. Of these, only irradiation with UV -B light for at least 45 min was efficient in controlling Vibrio . Irradiations with VIS light were subsequently repeated under PACT conditions in dose—response experiments with two water-soluble porphyrins, [T4(MePy)P] and [TPPS 4]. Disinfections of samples were successful for both porphyrin types at minimum concentrations of 10 ΜM and 24 h of irradiation.

https://dx.doi.org/10.1111/are.13128

Triptycene scaffolds: Synthesis and properties of triptycene-derived Schiff base compounds for the selective and sensitive detection of CN— and Cu2+

Emandi, G.; Browne, M. P.; Lyons, M. E.; Prior, C. and Senge, M. O. Triptycene scaffolds: Synthesis and properties of triptycene-derived Schiff base compounds for the selective and sensitive detection of CN- and Cu2+. Tetrahedron, 2017, 73, 2956—2965.

A series of triptycene-derived Schiff bases were synthesized by condensation between amino triptycenes with an appropriate aldehyde and were isolated in good to excellent (85—90%) yields. Amongst these, a triptycene-hydroxybenzaldehyde Schiff base compound proved to be a selective sensor for cyanide. It exhibited a ″turn-on″ fluorescence response at 490 nm to CN— facilitated by the nucleophilic addition of CN— to the aldehyde group, accompanied by a visible color change from orange to yellow. Likewise, a triptycene salicylaldehyde adduct was shown to be highly sensitive towards the detection of the CN— ion with a detection limit of 0.9 ΜM. On the other hand a triptycene-BODIPY Schiff base compound could be used for the detection of Cu2+ ions over other competing, biologically relevant metal ions in acetonitrile. Photophysical studies revealed a 1:1 binding model for the triptycene-BODIPY compound.

https://dx.doi.org/10.1016/j.tet.2017.04.005

Platinum(II) Ring-Fused Chlorins as Near-Infrared Emitting Oxygen Sensors and Photodynamic Agents

Pereira, N. A. M.; Laranjo, M.; Casalta-Lopes, J.; Serra, A. C.; Pineiro, M.; Pina, J.; Seixas de Melo, J. S.; Senge, M. O.; Botelho, M. F.; Martelo, L.; Burrows, H. D.; Pinho e Melo, T. M. V. D. Platinum(II) Ring-Fused Chlorins as Near-Infrared Emitting Oxygen Sensors and Photodynamic Agents. ACS Med. Chem. Lett. 2017, 8, 310—315.

Novel near-infrared luminescent compounds based on platinum(II) 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins are described. These compounds have high photostability and display light emission, in particular simultaneous fluorescence and phosphorescence emission in solution at room temperature, in the biologically relevant 700—850 nm red and near-infrared (NIR) spectral region, making them excellent materials for biological imaging. The simultaneous presence of fluorescence and phosphorescence emission at room temperature, with the phosphorescence strongly quenched by oxygen whereas fluorescence remains unaffected, allows these compounds to be used as ratiometric oxygen sensors in chemical and biological media. Both steady-state (fluorescence vs phosphorescence intensities) and dynamic (dependence of phosphorescence lifetimes upon oxygen concentration) luminescence approaches can be used. Photocytotoxicity studies against human melanocytic melanoma cells (A375) indicate that these compounds display potential as photosensitizers in photodynamic therapy.

https://dx.doi.org/10.1021/acsmedchemlett.6b00476

Organische Chemie 2016

Straub, B. F., Andexer, J., Arenz, C., Beifuss, U., Beuerle, F., Brasholz, M., Breinbauer, R., Ditrich, K., Gulder, T. A. M., Hüttel, W., Kordes, M., Krueger, A., Lehmann, M., Lindel, T., Luy, B., Meier, M. A. R., Mück-Lichtenfeld, C., Muhle-Goll, C., Müller, T. J. J., Narine, A., Paradies, J., Pfau, R., Pietruszka, J., Schaschke, N., Senge, M. O., Werner, T., Werz, D. B., Winter, C. A. and Worgull, D., Organische Chemie 2016, Nachr. Chem., 2016, 65, 266-304.

Molekulare SMS zur sicheren Nachrichtenübermittlung — außergewöhnliche Sternmesogene — enzymatische C-H-Insertion durch iridiumhaltiges Porphyrin — Totalsynthese hexacyclischer Daphniphyllum-Alkaloide — organokatalytische asymmetrische Cope-Umlagerung — Photoinduktion mit Elektronen-Relais-Strategie — FeCl3-katalysierte Carbonyl-Olefin-Kreuzmetathese — Psychedelic-NMR-Experiment — oral verfügbares Orphan Drug bei Morbus Fabry.

https://dx.doi.org/10.1002/nadc.20174059831

High-Content Imaging for Photosensitizer Screening

Vaz, G. M. F., Senge, M. O., Ryan, S.-L. and Davies, A., High-Content Imaging for Photosensitizer Screening, in: Imaging in Photodynamic Therapy (Eds.: Hamblin, M. R., Huang, Y.), CRC Press, Boca Raton, 2017, pp. 103-116.

Historically speaking, the rst photosensitizer (PS) to be used in a clinical setting was psoralen, still used today in psoriasis treatment (PUVA, psoralene and ultraviolet A radiation) (Figure 6.1). However, most commonly, photosensitizers are porphyrin derivatives due to not only their high absorption in the rednear-infrared region of light (signicantly increasing the depth at which PDT can be used in tissue), but they are also naturally occurring compounds and/or can be chemically synthesized and modied using ″simple″ chemical synthetic approaches (Juzeniene and Moan, 2007).

https://dx.doi.org/10.1201/b21922

Spectroelectrochemical Investigation of the One-Electron Reduction of Nonplanar Nickel(II) Porphyrins

Schindler, J., Kupfer, S., Zedler, L., Wächtler, M., Gräfe, S., Ryan, A. A., Senge, M. O. and Dietzek, B., Spectroelectrochemical Investigation of the One-Electron Reduction of Nonplanar Nickel(II) Porphyrins, ChemPhysChem, 2016, 17, 3480-3493.

The electrochemical reduction of a series of nickel porphyrins with an increasing number of substituents was investigated in acetonitrile. A one-electron reduction of [5,15-bis(1-ethylpropyl)porphyrinato]nickel(II) leads to π-anion radicals and to efficient formation of phlorin anions, presumably by disproportionation and subsequent protonation of the doubly reduced species.

https://dx.doi.org/10.1002/cphc.201600698

Glycosidase Activated Release of Fluorescent 1,8-Naphthalimide Probes for Tumor Cell Imaging from Glycosylated ′Pro-Probes′

Calatrava-Pérez, E., Bright, S. A., Achermann, S., Moylan, C., Senge, M. O., Veale, E. B., Williams, D. C., Gunnlaugsson, T. and Scanlan, E. M., Glycosidase Activated Release of Fluorescent 1,8-Naphthalimide Probes for Tumor Cell Imaging from Glycosylated ′Pro-Probes′, Chem. Commun., 2016, 52, 13086-13089.

Glycosylated 4-amino-1,8-naphthalimide derivatives possess a native glycosidic linkage that can be selectively hydrolysed in situ by glycosidase enzymes to release the naphthalimide as a fluorescent imaging or therapeutic agent. In vitro studies using a variety of cancer cell lines demonstrated that the naphthalimides only get taken up into cells upon enzymatic cleavage from the glycan unit; a mechanism that offers a novel approach for the targeted delivery of probes/drugs.

https://dx.doi.org/10.1039/c6cc06451e

Towards Electron Transfer Compounds with Rigid Resistor Units

Locke, G. M. and Senge, M. O., Towards Electron Transfer Compounds with Rigid Resistor Units, ECS Trans., 2016, 72, 1-11.

There is a growing need to access small rigid scaffolds for use in organic and medicinal chemistry. It is a requirement of many systems that the substituents are arranged in a precisely known, specific and invariable orientation. The applications of such scaffold span from host—guest interactions, photosynthesis, light harvesting and energy transfer amongst others. Both triptycene and cubane are rigid three dimensional scaffolds which are capable of arranging substituents in such a spatially defined manner.

https://dx.doi.org/10.1149/07216.0001ecs

Molecular Devices Based on Reversible Singlet Oxygen Binding in Optical and Photomedical Applications

Filatov, M. A. and Senge, M. O., Molecular Devices Based on Reversible Singlet Oxygen Binding in Optical and Photomedical Applications, Mol. Syst. Des. Eng., 2016, 1, 258-272.

Polycyclic aromatic hydrocarbons are known to bind singlet oxygen with formation of endoperoxides, which can be released upon heating. This process is now capturing broad attention due to its potential in photomedicine. Singlet oxygen generation upon decomposition of endoperoxides at ambient temperatures represents an alternative to classical photodynamic therapy (PDT), which is limited by hypoxia and reduced light penetration into cancer tissue.

https://dx.doi.org/10.1039/C6ME00042H

Nucleophilic Aromatic Substitution on Pentafluorophenyl-Substituted Dipyrranes and Tetrapyrroles as a Route to Multifunctionalized Chromophores for Potential Application in Photodynamic Therapy

Gutsche, C. S., Ortwerth, M., Gräfe, S., Flanagan, K. J., Senge, M. O., Reissig, H.-U., Kulak, N. and Wiehe, A., Nucleophilic Aromatic Substitution on Pentafluorophenyl-Substituted Dipyrranes and Tetrapyrroles as a Route to Multifunctionalized Chromophores for Potential Application in Photodynamic Therapy, Chem. Eur. J., 2016, 22, 13953-13964.

The application of porphyrinoids in biomedical fields, such as photodynamic therapy (PDT), requires the introduction of functional groups to tune their solubility for the biological environment and to allow a coupling to other active moieties or carrier systems. A valuable motif in this regard is the pentafluorophenyl (PFP) substituent, which can easily undergo a regiospecific nucleophilic replacement (SNAr) of its para-fluorine atom by a number of nucleophiles.

https://dx.doi.org/10.1002/chem.201601857

The Characterization of an Intestine-Like Genomic Signature Maintained during Barrett′s-Associated Adenocarcinogenesis Reveals an NR5A2-Mediated Promotion of Cancer Cell Survival

Duggan, S. P., Behan, F. M., Kirca, M., Zaheer, A., McGarrigle, S. A., Reynolds, J. V., Vaz, G. M. F., Senge, M. O. and Kelleher, D., The Characterization of an Intestine-Like Genomic Signature Maintained during Barrett′s-Associated Adenocarcinogenesis Reveals an NR5A2-Mediated Promotion of Cancer Cell Survival, 2016, 6, 32638.

Barrett′s oesophagus (BO), an intestinal-type metaplasia (IM), typically arising in conjunction with gastro-oesophageal reflux disease, is a prominent risk factor for the development of oesophageal adenocarcinoma (OAC). The molecular similarities between IM and normal intestinal tissues are ill-defined. Consequently, the contribution of intestine-enriched factors expressed within BO to oncogenesis is unclear. Herein, using transcriptomics we define the intestine-enriched genes expressed in meta-profiles of BO and OAC.

https://dx.doi.org/10.1038/srep32638

Studying the Intersystem Crossing Rate and Triplet Quantum Yield of Meso-Substituted Porphyrins by Means of Pulse Train Fluorescence Technique

de Souza, T. G. B., Viva, M. G., Mendoça, C. R., Plunkett, S., Filatov, M. A., Senge, M. O. and De Boni, L., Studying the Intersystem Crossing Rate and Triplet Quantum Yield of Meso-Substituted Porphyrins by Means of Pulse Train Fluorescence Technique, J. Porphyrins Phthalocyanines, 2016, 20, 1-10.

Excited state dynamics, particularly intersystem crossing, of a set of meso-substituted porphyrins bearing different electron—donor and acceptor groups was studied by pulse train fluorescence technique. Triplet quantum yield was found to be critically dependent on the nature of meso-substituents in the porphyrin system. Porphyrins with meso methoxyphenyl groups were found to show high triplet quantum yields (φT between 0.70 and 0.81).

https://dx.doi.org/10.1142/S1088424616500048

Current Developments in Using Meso-(Tetra)substituted Porphyrins for PDT

Shaker, Y. M., Sweed, A. M. K., Moylan, C.; Rogers, L., Ryan, A. A., Petitdemange, R. and Senge, M. O., Current Developments in Using Meso-(Tetra)substituted Porphyrins for PDT, in: Handbook of Photodynamic Therapy: Updates on Recent Applications of Porphyrin-Based Compounds (Eds.: Pandey, R. K., Kessel, D., Dougherty, T. J.), World Scientific, Singapore, 2016, pp. 95-149.

meso-Substituted porphyrins present a readily accessible class of porphyrins which has found wide applications in biomedical sciences. Contemporary syntheses allow the generation of large libraries of compounds with variable meso-substituents or the preparation of bioconjugates. This chapter summarizes current synthetic strategies and medicinal chemistry applications of meso-substituted porphyrins in photodynamic therapy (PDT).

https://dx.doi.org/10.1142/9789814719650_0003

A Two-Pronged Attack on DNA: Targeting Guanine Quadruplexes with Nonplanar Porphyrins and DNA-Binding Small Molecules

Rozas, I. and Senge, M. O., A Two-Pronged Attack on DNA: Targeting Guanine Quadruplexes with Nonplanar Porphyrins and DNA-Binding Small Molecules, Future Med. Chem., 2016, 8, 609-612.

A combination of DNA-binding small molecules with fluorescent, nonplanar porphyrins within one system can offer potential as theranostic agents for nucleic acid targeting.

https://dx.doi.org/10.4155/fmc-2016-0040

Organische Chemie

Itzen, A., Schaschke, N., Beifuss, U., Lehmann, M., Krueger, A., Beuerle, F., Senge, M. O., Breinbauer, R., Mück-Lichtenfeld, C., Müller, T. J. J., Denißen, M., Lindel, T., Pietruszka, J., Worgull, D., Gulder, T., Paradies, J., Muñiz, K., Bach, T., Ditrich, K., Winter, C., Kordes, M., von Deyn, W., Pfau, R., Muhle-Goll, C., Luy, B., Werz, D. B., Arenz, C., Hüttel, W., Andexer, J. N. and Straub, B. F., Organische Chemie, Nachr. Chem., 2016, 64, 255-294.

Siliciumrhodaminderivate weisen Formaldehyd nach — neues Nanomaterial: Graphitphasen polymeren Kohlenstoffnitrids — molekulare Drähte — homogene Cof-Dünnschichten bei Raumtemperatur — Biosyntheserekord: 1,8 MDa großes kolGen — [3,3]-sigmatrope Umlagerung führt zu quartären Stereozentren.

https://dx.doi.org/10.1002/nadc.20164047492

Contribution of Bacteriochlorophyll Conformation to the Distribution of Site-Energies in the FMO Protein

MacGowan, S. A. and Senge, M. O., Contribution of Bacteriochlorophyll Conformation to the Distribution of Site-Energies in the FMO Protein, Biochim. Biophys. Acta, 2016, 1857, 427-442.

The structural data for the Fenna—Matthews—Olson (FMO) protein indicate that the bacteriochlorophylls (BChls) display a significant degree of conformational heterogeneity of their peripheral substituents and the protein-induced nonplanar skeletal deformations of the tetrapyrrole macrocycle. As electronic properties of chromophores are altered by such differences, a conformational effect may influence the site-energies of specific pigments and thus play a role in mediating the excitation energy transfer dynamics, but this has not yet been established.

https://dx.doi.org/10.1016/j.bbabio.2016.02.001

Drug Discovery Approaches Utilizing Three-Dimensional Cell Culture

Ryan, S.-L., Baird, A.-M., Vaz, G., Urquhart, A. J., Senge, M. O., Richard, D. J., O'Byrne, K. J. and Davies, A. M., Drug Discovery Approaches Utilizing Three-Dimensional Cell Culture, Assay Drug Dev. Technol., 2016, 14, 19-28.

Historically, two-dimensional (2D) cell culture has been the preferred method of producing disease models in vitro. Recently, there has been a move away from 2D culture in favor of generating three-dimensional (3D) multicellular structures, which are thought to be more representative of the in vivo environment. This transition has brought with it an influx of technologies capable of producing these structures in various ways.

https://dx.doi.org/10.1089/adt.2015.670

Preparation of Tri- and Hexasubstituted Triptycene Synthons by Transition Metal Catalyzed Cross-Coupling Reactions for Post-Modifications

Moylan, C., Rogers, L., Shaker, Y. M., Davis, M., Eckhardt, H.-G., Eckert, R., Ryan, A. A. and Senge, M. O., Preparation of Tri- and Hexasubstituted Triptycene Synthons by Transition Metal Catalyzed Cross-Coupling Reactions for Post-Modifications, Eur. J. Org. Chem., 2015, 185-195.

Rational building strategies and appropriate synthons have been developed for the use of triptycene as a rigid presenting scaffold. Palladium-catalyzed cross-coupling reactions, such as Sonogashira and Suzuki couplings, were used to install a variety of different synthetic handles around the triptycene periphery in a high-yielding and controlled manner.

https://dx.doi.org/10.1002/ejoc.201501272

Crystal Structure of 5-Tert-butyl-10,15,20-triphenylporphyrin

Flanagan, K. J., Mothi, E. M., Kötzner, L. and Senge, M. O., Crystal Structure of 5-Tert-butyl-10,15,20-triphenylporphyrin, Acta Cryst., 2016, E72, 128-132.

In the title free base porphyrin, C42H34N4, the neighbouring N⋯N distances in the center of the ring vary from 2.818 (8) to 2.998 (8) Å and the phenyl rings are tilted from the 24-atom mean plane at angles varying between 62.42 (2)-71.63 (2)°. The NH groups are involved in intramolecular bifurcated N-H⋯(N,N) hydrogen bonds. The Ca-Cm-Ca angles vary slightly for the phenyl rings, between 124.19 (18)-126.17 (18)°.

https://dx.doi.org/10.1107/S2056989016000025

Conformational and Structural Studies of Meso Monosubstituted Metalloporphyrins—Edge-on Molecular Interactions of Porphyrins in Crystals

Senge, M. O., Flanagan, K. J., Ryan, A. A., Ryppa, C., Donath, M. and Twanley, B., Conformational and Structural Studies of Meso Monosubstituted Metalloporphyrins—Edge-on Molecular Interactions of Porphyrins in Crystals, Tetrahedron, 2016, 72, 105-115.

A series of meso monosubstituted metalloporphyrins were synthesized to assess the structural chemistry of porphyrins with only one substituent. The structures of four nickel(II) and zinc(II) complexes with either alkyl or aryl residues indicate primarily planar macrocycles. This gives rise to a different type of π-interactions in the crystal and the formation of dimeric, trimeric or tetrameric porphyrin units that function as building blocks for the overall crystal structure.

https://dx.doi.org/10.1016/j.tet.2015.11.008

Conformational Control of Cofactors in Nature — the Influence of Protein-Induced Macrocycle Distortion on the Biological Function of Tetrapyrroles

Senge, M. O., MacGowan, S. A. and O'Brien, J., Conformational Control of Cofactors in Nature — the Influence of Protein-Induced Macrocycle Distortion on the Biological Function of Tetrapyrroles, Chem. Commun., 2015, 51, 17031-17063.

Tetrapyrrole-containing proteins are one of the most fundamental classes of enzymes in nature and it remains an open question to give a chemical rationale for the multitude of biological reactions that can be catalyzed by these pigment—protein complexes. There are many fundamental processes where the same (i.e., chemically identical) porphyrin cofactor is involved in chemically quite distinct reactions.

https://dx.doi.org/10.1039/C5CC06254C

Getting it Right: 3D Cell Cultures for the Assessment of Photosensitizers for Photodynamic Therapy

Senge, M. O. and Stafford, S., Getting it Right: 3D Cell Cultures for the Assessment of Photosensitizers for Photodynamic Therapy, Future Med. Chem., 2015, 7, 1957-1960.

Cancer drug screening is rapidly moving towards the use of 3D cell models. The added complexity of PDT action makes this a conditio sine qua non for the screening of new photosensitizers.

https://dx.doi.org/10.4155/fmc.15.133

Crystal Structure of [5-n-Butyl-10-(2,5-dimethoxy-phenyl)-2,3,7,8,13,12,17,18-octaethylporphyrin-ato]nickel(II)

Flanagan, K. J., Mothi, E. M., Kötzner, L. and Senge, M. O., Crystal Structure of [5-n-Butyl-10-(2,5-dimethoxy-phenyl)-2,3,7,8,13,12,17,18-octaethylporphyrin-ato]nickel(II), Acta Cryst., 2015, E71, 1397-1400.

The asymmetric unit of the title nickel(II) porphyrin, [Ni(C48H60N4O2)], contains one independent molecule. The average Ni—N bond length is 1.917 (13) Aa;. The molecules are arranged in a closely spaced lattice structure in which neighbouring porphyrins are oriented in inversion-related dimers. The nickel(II) porphyrin is characterized by a significant degree of a ruffled (B1u) conformation with small contributions from saddle (B2u) and wave (y) [Eg(y)], as determined using normal structural decomposition.

https://dx.doi.org/10.1107/S2056989015020058

Specific Drug Formulation Additives: Revealing the Impact of Architecture and Block Length Ratio

Wieczorek, S., Schwaar, T., Senge, M. O. and Börner, H. G., Specific Drug Formulation Additives: Revealing the Impact of Architecture and Block Length Ratio, Biomacromolecules, 2015, 16, 3308-3312.

Combining poly(ethylene glycol) (PEG) with sequence-defined peptides in PEG—peptide conjugates offers opportunities to realize next-generation drug formulation additives for overcoming undesired pharmacological profiles of difficult small molecule drugs. The tailored peptide segments provide sequence-specific, noncovalent drug binding, and the hydrophilic PEG block renders the complexes water soluble. On the basis of a peptide sequence known to bind the photosensitizer m-tetra(hydroxyphenyl)chlorin (m-THPC) for photodynamic cancer therapy, a set of different conjugate architectures is synthesized and studied.

https://dx.doi.org/10.1021/acs.biomac.5b00961

Crystal Structure of 4-(Methoxycarbonyl)phenyl-boronic acid

Flanagan, K. J. and Senge, M. O., Crystal Structure of 4-(Methoxycarbonyl)phenyl-boronic acid, Acta Cryst., 2015, 71, 1151-1154.

In the title compound, C8H9BO4, the methoxycarbonyl group is rotated out of the plane of the benzene ring by 7.70 (6)°. In the crystal, molecules are linked via pairs of O—H⋯O hydrogen bonds, involving the boronic acid OH groups, forming inversion dimers. The dimers are linked via O—H⋯O hydrogen bonds, involving a boronic acid OH group and the carbonyl O atom, forming undulating sheets parallel to (10-2).

https://dx.doi.org/10.1107/s2056989015015923

Crystal Structures of 2-Furylbenzimidazoles with Antiangiogenic Inhibition of VEGF in Cell Line MCF-7

Flanagan, K. J., Shaker, Y. M., Temirak, A., El Diwani, H. I. and Senge, M. O., Crystal Structures of 2-Furylbenzimidazoles with Antiangiogenic Inhibition of VEGF in Cell Line MCF-7, Heterocycles, 2015, 91, 1603-1613.

The first crystal structures of four 2-furylbenzimidazole acetohydrazide derivatives are reported herein. The compounds have been shown to be planar with a small cant that varies from 4 to 30°. The X-ray crystal structure of the compounds 7-10 revealed that compounds are oriented in the cis configuration which suggests that the acid hydrazide group is essential for the enhanced potency of 2-furylbezimidazoles as anti-angiogenic agents.

https://dx.doi.org/10.3987/COM-15-13258

N-H Hydrogen Bonding in Porphyrins - from Conformational Design to Supramolecular Chemistry

Senge, M. O., N-H Hydrogen Bonding in Porphyrins - from Conformational Design to Supramolecular Chemistry, ECS Trans., 2015, 66, 1-10.

Typically porphyrin N-H units are not involved in intermolecular hydrogen bonds as they are 'shielded' by the macrocycle system. However, two possibilities exist to utilize the pyrrole nitrogen atoms in such bonds: a) Porpho(di)methenes and phlorins (calixphyrin-type systems) contain sp3-hybridized meso positions and the interruption of the aromatic system gives rise to specific cavities and often roof- or bowl-shaped conformations making the core nitrogen and N—H units more accessible for coordination. b) Likewise, saddle-distorted nonplanar porphyrins are very basic and can bind anions and neutral molecules via N-H hydrogen bonds in the core.

https://dx.doi.org/10.1149/06616.0001ecst

Chemical Synthesis and Medicinal Applications of Glycoporphyrins

Moylan, C., Scanlan, E. M. and Senge, M. O., Chemical Synthesis and Medicinal Applications of Glycoporphyrins, Curr. Med. Chem., 2015, 22, 2238-2348.

This review presents an in-depth overview of the modification of porphyrins with bioconjugates and their applications in medicine today. Porphyrin bioconjugates ranging from nucleotides to steroids are under active scrutiny. However, carbohydrates have been at the forefront of such research in recent years and offer significant potential. This is attributed to their own selectivity to lectins on the surface of cancer cells and their influence on the amphiphilicity of the porphyrin macrocycle.

https://dx.doi.org/10.2174/0929867322666150429113104

Lead Structures for Applications in Photodynamic Therapy 7. Efficient Synthesis of Amphiphilic Glycosylated Lipid Porphyrin Derivatives: Refining Linker Conjugation for Potential PDT Applications

Moylan, C., Sweed, A. M. K., Shaker, Y. M., Scanlan, E. M. and Senge, M. O., Lead structures for applications in photodynamic therapy 7. Efficient synthesis of amphiphilic glycosylated lipid porphyrin derivatives: refining linker conjugation for potential PDT applications, Tetrahedron, 2015, 71, 4145-4153.

Herein, we report synthetic strategies towards a library of amphiphilic tetraphenyl porphyrins anchored to synthetic saccharides and lipid modalities. The carbohydrates and lipid functionalities are covalently linked to the model photosensitizer via a copper (I) catalyzed alkyne azide cycloaddition reaction or an oxypropyl linkage achieved by nucleophilic substitution chemistry.

https://dx.doi.org/10.1016/j.tet.2015.04.097

Lead Structures for Applications in Photodynamic Therapy. 6. Temoporfin Anti-Inflammatory Conjugates to Target the Tumor Microenvironment for In Vitro PDT

Rogers, L., Sergeeva, N. N., Paszko, Vaz, G. M. F., Senge, M. O., Lead Structures for Applications in Photodynamic Therapy. 6. Temoporfin Anti-Inflammatory Conjugates to Target the Tumor Microenvironment for In Vitro PDT, PLoS One, 2015, 10, e0125372.

Due to the ongoing development of clinical photodynamic therapy (PDT), the search continues for optimized photosensitizers that can overcome some of the side effects associated with this type of treatment modality. The main protagonists being: post-treatment photosensitivity, due to only limited cellular selectivity and post-treatment tumor regrowth, due to the up-regulation of pro-inflammatory agents within the tumor microenvironment.

https://dx.doi.org/10.1371/journal.pone.0125372

Pdots, a new type of nanoparticle, bind to mTHPC via their lipid modified surface and exhibit very high FRET efficiency between the core and the sensitizer

Haupt, S., Lazar, I., Weitman, H., Senge, M. O., Ehrenberg, B., Pdots, a new type of nanoparticle, bind to mTHPC via their lipid modified surface and exhibit very high FRET efficiency between the core and the sensitizer, Phys. Chem. Chem. Phys., 2015, 17, 11412-11422.

Pdots are a new type of nanoparticle which exhibit strong potential for future applications in biophysics and cell biology. They are composed of organic chromophoric polymers, whose surfaces can be modified with different amphiphilic polymers, such as PEGylated lipids to make them very stable as colloids in water.

https://dx.doi.org/10.1039/C4CP05579A

Highly Strained Tertiary sp3 Scaffolds: Synthesis of Functionalized Cubanes and Exploration of Their Reactivity under Pd(II) Catalysis

Plunkett, S., Flanagan, K. J., Twamley, B., Senge, M. O., Highly Strained Tertiary sp3 Scaffolds: Synthesis of Functionalized Cubanes and Exploration of Their Reactivity under Pd(II) Catalysis, Organometallics, 2015, 34, 7, 1408-1414.

A series of chemically distinct, highly strained, activated cubane scaffolds were synthesized through optimization of the metal—halogen exchange reactions of iodinated cubane derivatives. This included the first reported successful attachment of both boron and phosphorus, key elements in potential transition-metal-catalyzed cross-coupling reactions, on the cubane scaffold.

https://dx.doi.org/10.1021/acs.organomet.5b00151

How green is green chemistry? Chlorophylls as a bioresource from biorefineries and their commercial potential in medicine and photovoltaics

Ryan, A. A., Senge, M. O., How green is green chemistry? Chlorophylls as a bioresource from biorefineries and their commercial potential in medicine and photovoltaics, Photochem. Photobiol. Sci., 2015, 14, 638-660.

As the world strives to create a more sustainable environment, green chemistry has come to the fore in attempts to minimize the use of hazardous materials and shift the focus towards renewable sources. Chlorophylls, being the definitive ″green″ chemical are rarely used for such purposes and this article focuses on the exploitation of this natural resource⋯

https://dx.doi.org/10.1039/C4PP00435C

Organische Chemie 2014

Beifuss, U., Lehmann, M., Krueger, A., Beuerle, F., Senge, M. O., Breinbauer, R., Mück-Lichtenfeld, C., Gers, C. F., Müller, T. J. J., Lindel, T., Worgull, D., Pietruszka, J., Paradies, J., Bach, T., Muniz, K., Straub, B. F., Stark, A., Ditrich, K., von Deyn, W., Kordes, M., Wiebe, C., Pfau, R., Luy, B., Muhle-Goll, C., Arenz, C., Sewald, N., Andexer, J., Hüttel, W., Itzen, A. and Werz, D. B., Organische Chemie, Nachr. Chem., 2015, 63, 266-305.

Neuartiges Luciferin — enantioselektive Photoreaktionen — Homogenkatalyse: Selektivitäten und Intermediate — verringerte NMR-Probenmengen — repetitive Zellwand-Polysaccharide — funktionale Nanostrukturen

https://dx.doi.org/10.1002/nadc.201590092

Porphyrin substituent regiochemistry, conformation and packing — the case of 5,10-diphenylporphyrin

Senge, M. O., Dahms, K., Holdt, H.-J., Kelling, A., Porphyrin substituent regiochemistry, conformation and packing — the case of 5,10-diphenylporphyrin, Z. Naturforsch., 2015, 70b, 2, 119-123.

5,10-Disubstituted porphyrins are more recent additions to the family of meso-substituted porphyrins. A crystallographic comparison of 5,10-diphenylporphyrin with the regioisomeric 5,15-disubstituted system reveals striking differences in their conformation. In the free base porphyrins the former uses mainly out-of-plane distortion to alleviate steric strain while in-plane core elongation predominates in the latter.

https://dx.doi.org/10.1515/znb-2014-0217

Lead structures for applications in photodynamic therapy. 5. Synthesis and biological evaluation of water soluble phosphorus(V) 5,10,15,20-tetraalkylporphyrins for PDT

Ryan, A. A., Ebrahim, M. M., Petitdemange, R., Vaz, G. M., Paszko, E., Sergeeva, N. N., Senge, M. O., Lead structures for applications in photodynamic therapy. 5. Synthesis and biological evaluation of water soluble phosphorus(V) 5,10,15,20-tetraalkylporphyrins for PDT, Photodiagn. Photodyn. Ther., 2014, 11, 4, 510-515.

Improved photosensitizers for use in photomedicine must possess good water-solubility and optimal photophysical properties. Phosphorus(V) porphyrins fulfill these criteria and are a class of porphyrins with significant potential applications in phototherapy. Five phosphorus(V) porphyrins bearing alkyl substituents have been synthesized. Reasonable to good yields were obtained for all P(V) insertions and all compounds underwent biological evaluation for their PDT activity on two esophageal cancer cell lines, OE33 and SKGT-4.

https://dx.doi.org/10.1016/j.pdpdt.2014.07.003

Structural investigation of 5,10-A2B2-type porphyrins: palladium(II) and zinc(II) complexes of 5,10-dibromo-15,20-bis(4-methylphenyl)porphyrin

Senge, M. O., Zawadzka, M., Structural investigation of 5,10-A2B2-type porphyrins: palladium(II) and zinc(II) complexes of 5,10-dibromo-15,20-bis(4-methylphenyl)porphyrin, Acta Crystallogr., Sect. C: Struct. Chem., 2014, C70, 12, 1143-1146.

The analysis of [5,10-dibromo-15,20-bis(4-methylphenyl)porphyrinato]palladium(II), [Pd(C34H22Br2N4)], and [5,10-dibromo-15,20-bis(4-methylphenyl)porphyrinato](methanol)zinc(II), [Zn(C34H22Br2N4)(CH4O)], reveals a small but localized influence of the bromine residues on the conformation of the macrocycle. A comparison of the 5,10-dibromo substituent pattern with literature data for 5,15-dibromoporphyrins shows similar in-plane distortions in both but a different mix of out-of-plane distortion modes for the different regiochemical arrangements.

https://dx.doi.org/10.1107/S2053229614023687

Impact of Substituents and Nonplanarity on Nickel and Copper Porphyrin Electrochemistry: First Observation of a CuII/CuIII Reaction in Nonaqueous Media.

Fang, Y., Senge, M. O., Van Caemelbecke, E., Smith, K. M., Medforth, C. J., Zhang, M., Kadish, K. M., Impact of Substituents and Nonplanarity on Nickel and Copper Porphyrin Electrochemistry: First Observation of a CuII/CuIII Reaction in Nonaqueous Media., Inorg. Chem., 2014, 53, 19, 10772-10778.

Electrochemical studies of the oxidation of dodecasubstituted and highly nonplanar nickel porphyrins in a noncoordinating solvent have previously revealed the first nickel(III) porphyrin dication. Herein, we investigate if these nonplanar porphyrins can also be used to detect the so far unobserved copper(III) porphyrin dication.

https://dx.doi.org/10.1021/ic502162p

Tailoring Porphyrin (Nano)Structures

Ryan, A. A., Letchford, K. A., Senge, M. O., Tailoring Porphyrin (Nano)Structures, ECS Trans., 2014, 61, 34, 1-12.

Porphyrins present one of the most ubiquitous classes of compounds in chemistry, optics, medicine, and materials science. This is a result of their multifaceted roles in nature and the wide range of tunable molecular properties. Further advances in translational research and a more detailed understanding of their biological function require a specific tailoring of the macrocycle to the desired task.

https://dx.doi.org/10.1149/06134.0001ecst

Chlorophylls, Symmetry, Chirality, and Photosynthesis

Senge, M. O., Ryan, A. A., Letchford, K. A., MacGowan, S. A., Mielke, T., Chlorophylls, Symmetry, Chirality, and Photosynthesis, Symmetry, 2014, 6, 781-843.

Chlorophylls are a fundamental class of tetrapyrroles and function as the central reaction center, accessory and photoprotective pigments in photosynthesis. Their unique individual photochemical properties are a consequence of the tetrapyrrole macrocycle, the structural chemistry and coordination behavior of the phytochlorin system, and specific substituent pattern.

https://dx.doi.org/10.3390/sym6030781

Crystal structure of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin

Senge, M. O., Eckhardt, H.-G., Crystal structure of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin, Acta Crystallogr. Sect. E: Struct. Rep. Online, 2014, E70, o1085-o1086.

In the title compound, C44H37BN4O2, the dihedral angle between the plane of the porphyrin macrocycle ring system [r.m.s. deviation = 0.159 (1) Å] and those of three phenyl rings are 66.11 (4), 74.75 (4) and 57.00 (4)º. The conformational distortion is characterized by a mixture of ruffled, saddle and in-plane distortion modes.

https://dx.doi.org/10.1107/S1600536814019680

Synthesis of Diazepine-fused Porphyrinoids and Annulated Porphyrin Arrays

Ryan, A. A., Pouyatos, F., Stallivieri, A., Balaban, T. S., Senge, M. O., Synthesis of Diazepine-fused Porphyrinoids and Annulated Porphyrin Arrays, Z. Naturforsch., 2014, 69b, 889-898.

Porphyrins with exocyclic rings allow for significant modulation of the photochemical properties of the macrocycle via modulation of the aromatic system through electronic and conformational effects. Here we sought to generate such porphyrinoids via a stepwise strategy involving two cycloaddition steps, the first improving the synthesis of a relatively unstable dehydropurpurin intermediate which ring opens to form a key 1,5-diketone species.

https://dx.doi.org/10.5560/znb.2014-4100

Simple Porphyrin Desymmetrization: 5,10,15,20-Tetrakis(3-hydroxyphenyl)porphyrin (m-THPP) as a Gateway Molecule for Peripheral Functionalization

Rogers, L., Burke-Murphy, E., Senge, M. O., Simple Porphyrin Desymmetrization: 5,10,15,20-Tetrakis(3-hydroxyphenyl)porphyrin (m-THPP) as a Gateway Molecule for Peripheral Functionalization, 2014, 2014, 20, 4283-4294.

This study details the development of a facile approach to unsymmetrical porphyrins that starts from the known photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (m-THPP) and employs nucleophilic substitution, esterification, and metal-catalyzed cross-coupling reactions. The room temperature reactions proceeded in excellent yields to provide a valuable gateway to new photosensitizers.

https://dx.doi.org/10.1002/ejoc.201402433

The translocator protein as a potential molecular target for improved treatment efficacy in photodynamic therapy

Rogers, L., Senge, M. O., The translocator protein as a potential molecular target for improved treatment efficacy in photodynamic therapy, Future Med. Chem., 2014, 6, 7, 775-792.

Since its serendipitous discovery over 30 years ago, the translocator protein (18 kDa) has been demonstrated to play an important role in a multitude of critical biological processes. Although implemented as a novel therapeutic and diagnostic tool for a variety of disease states, its most promising role is as a molecular target for anticancer treatments such as photodynamic therapy (PDT).

https://dx.doi.org/10.4155/fmc.14.37

(5-n-Butyl-10,20-diisobutylporphyrinato)nickel(II)

Senge, M. O., Dahms, K., (5-n-Butyl-10,20-diisobutylporphyrinato)nickel(II), Acta Crystallogr. Sect. E: Struct. Rep. Online., 2014, E70, m251.

The asymmetric unit of the title compound, [Ni(C32H36N4)], contains two independent molecules exhibiting an overall ruffled conformation of the porphyrin macrocycle and differing mainly in the positions of the methyl groups. The average Ni-N bond lengths are 1.912 (2) and 1.910 (2) Å in the two molecules.

https://dx.doi.org/10.1107/S1600536814012884

Licht für Medizin und Diagnostik

Griesbeck, A., Ihmels, H., Licha, K., Mielke, T., Senge, M. O., Strehmel, B. and Wöll, D., Licht für Medizin und Diagnostik, Nachr. Chem., 2014, 62, 612-616.

Tumortherapie, bildgebende Diagnostik, Fluoreszenzmikroskopie und schaltbare Materialien nutzen und profitieren von photochemischen und photophysikalischen Methoden.

https://dx.doi.org/10.1002/nadc.201490196

Organische Chemie 2013

Beuerle, F., Krueger, A., Lehmann, M., Bach, T., Beifuss, U., Müller, T. J. J., Giernoth, R., Ditrich, K., Straub, B. F., Schreiner, P. R., Lindel, T., Böse, D., Pietruszka, J., Pfau, R., Breinbauer, R., Sewald, N., Weinhold, E., Arenz, C., Andexer, J., Müller, M., von Deyn, W., Kordes, M., Wiebe, C., Muniz, K., Senge, M. O., Paradies, J., Luy, B., Muhle-Goll, C., Biskup, M. B. and Bräse, S., Organische Chemie 2013, Nachr. Chem., 2014, 62, 264-301.

Fluid-enhanced crystal engineering — zytosolische DNA-Sensoren — Metall-Carben-Komplexe in der Biokatalyse — Photochemische Cyclisierungen

https://dx.doi.org/10.1002/nadc.201490086

Ni—Cu ion exchange observed for Ni(II)—porphyrins on Cu(111)

Doyle, C. M., Cunniffe, J. P., Krasnikov, S. A., Preobrajenski, A. B., Li, Z., Sergeeva, N. N., Senge, M. O., Cafolla, A. A., Ni—Cu ion exchange observed for Ni(II)—porphyrins on Cu(111), Chem. Commun., 2014, 50, 3447-3449.

A Ni—Cu ion exchange has been observed for (5,15-dibromo-10,20-diphenylporphyrinato)nickel(II) (NiDBrDPP) and (5,10,15,20-tetrakis(4-bromophenyl)porphyrinato)nickel(II) (NiTBrPP) on Cu(111). The ion exchange proceeds at a faster rate for the NiDBrDPP/Cu(111) system compared to NiTBrPP/Cu(111). This is explained in terms of the macrocycle—substrate distance and the distortions that occur when the molecules are deposited on the Cu(111) surface.

https://dx.doi.org/10.1039/C3CC48913B

Effects of Preparation Conditions of Poly(lactide-co-glycolide) Nanoparticles Loaded with Amphiphilic Porphyrins and Their Photoactivities.

da Silveria, J. M., da Silva, A. R., Senge, M. O., Jorge, R. A., Effects of Preparation Conditions of Poly(lactide-co-glycolide) Nanoparticles Loaded with Amphiphilic Porphyrins and Their Photoactivities., J. Nanosci. Nanotechnol., 2014, 14, 8, 6274-6286.

Three porphyrins, (5,10,15,20-tetra(3-hydroxyphenyl)porphyrin, 5-hexyl-10,20-bis(3-hydroxyphenyl)-porphyrin and 5-hexyl-10,15,20-tris(3-hydroxyphenyl)porphyrin), with different amphiphilicities and equal singlet oxygen quantum yields in ethanol, were encapsulated into 50:50 poly(lactide-coglycolide), nanoparticles prepared by the emulsion/evaporation technique. A 22 factorial design was utilized to evaluate the influence of the porphyrin/polymer mass ratio and the percentage of ethanol in the aqueous phase on the size and zeta potential of the nanoparticles.

https://dx.doi.org/10.1166/jnn.2014.8855

Micro- or nanorod and nanosphere structures derived from a series of phenyl-porphyrins

Reddy, M. H. V., Al-Shammari, R. M., Al-Attar, N., Kennedy, E., Rogers, L., Lopez, S., Senge, M. O., Keyes, T. E., Rice, J. H., Micro- or nanorod and nanosphere structures derived from a series of phenyl-porphyrins, Phys. Chem. Chem. Phys., 2014, 16, 4386-4393.

We examine here a series of meso-phenyl porphyrin micro- and nanostructures. Optical absorption and emission spectroscopy imaging and atomic force microscopy are used to investigate the effect of peripheral groups in nano- and microstructures of 5,10,15,20-tetraphenylporphyrin (H2TPP) compared to three other phenylporphyrins, i.e. 5,10,15-triphenylporphyrin (H2-Tri-PP), 5,10-diphenylporphyrin (H25,10-BPP) and 5,15-diphenylporphyrin (H25,15-BPP) molecules.

https://dx.doi.org/10.1039/C3CP54936D

Fractal structures in n-phenyl-porphyrin J-aggregate films

Reddy, M. H. V., Al-Shammari, R. M., Al-Attar, N., Rogers, L., Lopez, S., Forster, R. J., Senge, M. O., Keyes, T. E., Rice, J. H., Fractal structures in n-phenyl-porphyrin J-aggregate films, Mater. Chem. Phys., 2014, 143, 3, 963-968.

Studied here are thin films of a series of phenyl-porphyrins. The effect of the phenyl number and positioning on the porphyrin core is shown to have a significant impact on the ability of phenyl-porphyrins to produce aggregates. When four phenyl groups (H2TPP) and three phenyl groups are present (H2-Tri-PP) a strong aggregate film forms with fractal like structure.

https://dx.doi.org/10.1016/j.matchemphys.2013.10.030

From thioether substituted porphyrins to sulfur linked porphyrin dimers: an unusual SNAr via thiolate displacement?

Ryan, A. A., Plunket, S., Casey, A, McCabe, T., Senge, M. O., Chem. Commun., 2014, 50, 353-355.

Treatment of meso 2-ethylhexyl-3-mercaptopropionate substituted porphyrins with base at room temperature generated a porphyrin thiolate anion which in situ reacted in a nucleophilic aromatic substitution (SNAr) reaction with remaining thioether derivative. This reaction yielded S-linked bisporphyrins in good yields, with mechanistic insight obtained via displacement reactions. Additionally, SNAr of the thioether chain was achieved using S- and organolithium nucleophiles.

https://dx.doi.org/10.1039/C3CC46828C

Laser induced protonation of free base porphyrin in chloroform results in the enhancement of positive nonlinear absorption due to conformational distortion

Zawadzka, M., Wang, J., Blau, W. J., Senge, M. O., Laser induced protonation of free base porphyrin in chloroform results in the enhancement of positive nonlinear absorption due to conformational distortion, J. Porphyrins Phthalocyanines, 2013, 17, 11, 1129-1133.

Free base porphyrin in chloroform solution irradiated with focused laser beam, in an open Z-scan set-up, changed color from purple to green, which was associated with protonation of the porphyrin with protonic species from photodegradation of the solvent. Protonation is demonstrated as a simple means to improve the optical limiting performance of free base porphyrin nonlinear optical (NLO) materials.

https://dx.doi.org/10.1142/S108842461350082X

Solvent effect on the nonlinear absorption of 5,10-A2B2meso substituted porphyrins

Zawadzka, M., Wang, J., Blau, W. J., Senge, M. O., Solvent effect on the nonlinear absorption of 5,10-A2B2meso substituted porphyrins, Photochem. Photobiol. Sci., 2013, 12, 1811-1823.

The effect of the solvent on the nonlinear absorptive properties of two series of 5,10-A2B2 porphyrins was investigated with an open Z-scan technique in the ns time regime. The recorded responses, which varied between compounds and solvents, were fitted to a four-level model where the one-photon excited state absorption is followed by a two-photon process arising from the higher excited states.

https://dx.doi.org/10.1039/C3PP50156F

High Content Screening as High Quality Assay for Biological Evaluation of Photosensitizers In Vitro

Vaz, G. M. F., Paszko, E., Davies, A. M., Senge, M. O., High Content Screening as High Quality Assay for Biological Evaluation of Photosensitizers In Vitro, PLoS One, 2013, 8, 7, e70653.

A novel single step assay approach to screen a library of photodynamic therapy (PDT) compounds was developed. Utilizing high content analysis (HCA) technologies several robust cellular parameters were identified, which can be used to determine the phototoxic effects of porphyrin compounds which have been developed as potential anticancer agents directed against esophageal carcinoma.

https://dx.doi.org/10.1371/journal.pone.0070653

Synthesis and Functionalization of Triply Fused Porphyrin Dimers

Ryan, A. A, Senge, M. O., Synthesis and Functionalization of Triply Fused Porphyrin Dimers, Eur. J. Org. Chem., 2013,18, 3700-3711.

A library of symmetric and unsymmetric singly linked and triply fused porphyrin dimers are synthesized in moderate to very good yields. A variety of functional groups are tolerated. Numerous synthetic strategies, incorporating oxidative radical coupling and organolithium and palladium-catalyzed coupling methods, are utilized.

https://dx.doi.org/10.1002/ejoc.201201622

5,15-Bis(4-pentyloxyphenyl)porphyrin

Senge, M. O., 5,15-Bis(4-pentyloxyphenyl)porphyrin, Acta Crystallogr. Sect. E: Struct. Rep. Online, 2013, E69, o1048.

In the title compound, C42H42N4O2, the complete molecule is generated by a crystallographic inversion centre. The porphyrin system exhibits a near planar macrocycle conformation with an average deviation from the least-squares plane of the 24 macrocycle atoms of 0.037 (5) Å.

https://dx.doi.org/10.1107/S160053681301550X

Nonlinear absorption properties of 5,10-A2B2 porphyrins — Correlation of molecular structure with the nonlinear responses

Zawadzka, M., Wang, J., Blau, W. J., Senge, M. O., Nonlinear absorption properties of 5,10-A2B2 porphyrins — Correlation of molecular structure with the nonlinear responses, Photochem. Photobiol. Sci., 2013, 12, 996-1007.

The nonlinear absorption properties of two series of novel free base and metalated meso 5,10-A2B2 substituted porphyrins, both bearing p-tolyl as an A substituent and TMS-ethynyl or bromine as a B substituent, were investigated with the open Z-scan technique at 532 nm in the ns time regime.

https://dx.doi.org/10.1039/c3pp25410k

Chemical Synthesis in Solution and Porphyrin Nanostructures on Surfaces - Similar Concepts, Different Results

Ryan, A. A., Cafolla, A. A., Senge, M. O., Chemical Synthesis in Solution and Porphyrin Nanostructures on Surfaces - Similar Concepts, Different Results, ECS Trans., 2013, 45, 20, 77-90.

The chemistry of porphyrins is reaching out to more complex and ever larger polyporphyrin arrays. In solution the synthesis of porphyrin arrays is greatly aided by recent advances in organometallic chemistry which now allows the rational construction of selected tetrapyrrole scaffolds. Examples for these are unsymmetrical porphyrin arrays with conjugating and nonconjugating linker groups and the use of presenting scaffolds such as triptycenes.

https://dx.doi.org/10.1149%2F04520.0077ecst

Synthesis and biological evaluation of Foscan® bile acid conjugates to target esophageal cancer cells

Rogers, L., Majer, F., Sergeeva, N. N, Paszko, E., Gilmer, J. F., Senge, M. O., Synthesis and biological evaluation of Foscan® bile acid conjugates to target esophageal cancer cells, Bioorg. Med. Chem. Lett., 2013, 23, 9, 2495-2499.

Porphyrins and chlorins such as Foscan® have a natural proclivity to accumulate in cancer cells. This trait has made them good candidates for photosensitizers and as imaging agents in phototherapy. In order to improve on cellular selectivity to lower post-treatment photosensitivity bile acid porphyrin bioconjugates have been prepared and investigated in esophageal cancer cells.

https://dx.doi.org/10.1016/j.bmcl.2013.03.040

Organische Chemie 2012

Beuerle, F., Krueger, A., Lehmann, M., Bach, T., Beifuss, U., Müller, T. J. J., Giernoth, R., Ditrich, K., Straub, B. F., Schreiner, P. R., Lindel, T., Böse, D., Pietruszka, J., Pfau, R., Breinbauer, R., Sewald, N., Weinhold, E., Arenz, C., Andexer, J., Müller, M., von Deyn, W., Kordes, M., Wiebe, C., Muniz, K., Senge, M. O., Paradies, J., Luy, B., Muhle-Goll, C., Biskup, M. B. and Bräse, S., Organische Chemie 2012, Nachr. Chem., 2013, 61, 265-297.

Graphene — Nanostrukturen aus DNA-Bausteinen — Tuberkulose-Diagnostik — Pyrrolysin — Fluorierungen — Strukturbiologie mit NMR — Haupt-Effekt.

https://dx.doi.org/10.1002/nadc.201390087

Synthesis and Reactivity of Allenylporphyrins

Plunkett, S., Dahms, K., Senge, M. O., Synthesis and Reactivity of Allenylporphyrins, Eur. J. Org. Chem., 2013, 2013, 8, 1566-1579.

The synthesis of a diverse library of allenylporphyrins by using two distinct metal-catalyzed pathways is described. The reactivities of both directly linked allenylporphyrins and those with a phenyl ″spacer″ have been investigated with promising results.

https://dx.doi.org/10.1002/ejoc.201201535

Platelets, Photosensitizers, and PDT.

Radomski, M. W., Senge, M. O., Platelets, Photosensitizers, and PDT, Photodiagn. Photodyn. Ther., 2013, 10, 1, 1-16.

Photodynamic therapy (PDT) has both direct cell and indirect vascular effects. Both are well established and the latter has given rise to specifically target angiogenesis in PDT treatments. While the vascular effects are well understood, further advances in anti-angiogenesis require a detailed understanding of PDT effects at the microvasculature level.

https://dx.doi.org/10.1016/j.pdpdt.2012.08.004

Computational Quantification of the Physicochemical Effects of Heme Distortion: Redox Control in the Reaction Center Cytochrome Subunit of Blastochloris viridis

MacGowan, S. A., Senge, M. O., Computational Quantification of the Physicochemical Effects of Heme Distortion: Redox Control in the Reaction Center Cytochrome Subunit of Blastochloris viridis, Inorg. Chem., 2013, 52, 3, 1228—1237.

A facile, experimentally calibrated computational procedure is described that affords the relative ordering of heme cofactor reduction potentials with respect to intrinsic shifts brought about by apoprotein induced heme-macrocycle distortion. The method utilizes heme-Fe partial atomic charges and is useful with the computationally inexpensive B3LYP/3-21g method calculated for simplified heme models extracted from the Protein Data Bank incorporating only the effects of varying macrocycle conformations and thereby delineating their physicochemical effects.

https://dx.doi.org/10.1021/ic301530t

Modeling of Nonlinear Absorption of 5,10-A2B2 Porphyrins in the Nanosecond Regime.

Zawadzka, M., Wang, J., Blau, W. J., Senge, M. O., Modeling of Nonlinear Absorption of 5,10-A2B2 Porphyrins in the Nanosecond Regime, J. Phys. Chem. A, 2013, 117, 1, 15—26

The nonlinear absorption (NLA) properties of free base and metalated porphyrins with a unique 5,10-A2B2 substitution pattern were studied with open Z-scan technique at 532 nm in the nanosecond regime over a broad range of input fluence. The NLA responses were found to be dependent on structural features and the solvent used.

https://dx.doi.org/10.1021/jp304817u

Transferrin conjugation does not increase the efficiency of liposomal Foscan during in vitro photodynamic therapy of oesophageal cancer

Paszko, E., Vaz, G. M. F., Ehrhardt, C., Senge, M. O., Transferrin conjugation does not increase the efficiency of liposomal Foscan during in vitro photodynamic therapy of oesophageal cancer, Eur. J. Pharm. Sci., 2013, 48, 1-2, 202-210

Photodynamic therapy (PDT) is based on the delivery of photocytotoxic agents to a target tissue, followed by irradiation. In order to increase the efficiency of PDT in oesophageal cancer therapy, polyethylene glycol (PEG)-grafted, transferrin (Tf)-conjugated liposome formulations of 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (Foscan), a second-generation photosensitiser, were prepared. Expression of transferrin receptors (CD71) in the oesophageal cancer cell line, OE21, was confirmed by immunoblot and confocal laser scanning microscopy.

https://dx.doi.org/10.1016/j.ejps.2012.10.018

The Molecular and Crystal Structures of Galvinol Derivatives

Senge, M. O., The Molecular and Crystal Structures of Galvinol Derivatives, Z. Naturforsch., 2012, 67b, 1137—1143.

Galvinols are interesting, sterically hindered compounds that serve as precursors for the generation of stable galvinoxyl radicals. In order to elucidate their basic structural chemistry and the influence of steric effects on their conformation a comparative analysis of several galvinol derivatives was undertaken. The aryl and quinoid subunits could clearly be identified, and substituents at the connecting methine bridge were found to influence the conformation of the molecules.

https://dx.doi.org/10.5560/znb.2012-0211

Synthesis and Biological Evaluation of a Library of Glycoporphyrin Compounds

Daly, R., Vaz, G., Davies, A. M., Senge, M. O., Scanlan, E. M., Synthesis and Biological Evaluation of a Library of Glycoporphyrin Compounds, Chem. Eur. J., 2012, 18, 46, 14671—14679

A library of glycosylated porphyrins (glycoporphyrins) was prepared and the compounds were evaluated for their photodynamic therapy (PDT) activity against the oesophageal squamous-cell carcinoma cell line OE21 in vitro. A synthetic methodology was developed to allow incorporation of biologically active carbohydrates, including the histo-blood-group antigen trisaccharide LewisX, onto the porphyrin backbone. The effect of the carbohydrate group and substitution pattern on the PDT activity, cell uptake and subcellular localisation of the glycoporphyrin compounds is reported.

https://dx.doi.org/10.1002/chem.201202064

Immunoliposomes

Paszko, E., Senge, M. O., Immunoliposomes, Curr. Med. Chem., 2012, 19, 31, 5239—5277.

Since their discovery by Bangham about 50 years ago, liposomes have become promising tools in drug delivery systems. This has increased the therapeutic index of many drugs, and offers improved drug targeting and controlled release. In order to further improve the specificity of liposomes for malignant tissues, targeted liposomal formulations have been developed which represent the next step of liposomal drug delivery in medical treatment. Antibodies and antibody fragments are the most widely used targeting moieties for liposomes due to the high specificity for their target antigens. This has given rise to a new class of drug delivery vehicles, the so-called immunoliposomes.

https://dx.doi.org/10.2174/092986712803833362

[5,15-Bis(2-methylpropyl)-porphyrinato]nickel(II)

Senge, M. O., [5,15-Bis(2-methylpropyl)-porphyrinato]nickel(II), Acta Cryst., 2012, E68, m1191-1192.

The title compound, [Ni(C28H28N4)], crystallizes with two independent molecules in the unit cell, one of which is located on an inversion center. Both macrocycles exhibit a planar conformation with average deviation from the least-squares-plane of the 24 macrocycle atoms of Δ24 = 0.043 Å for the first molecule and 0.026 Å for the molecule located on an inversion center.

https://dx.doi.org/10.1107/S1600536812035726

Photochemical Transformations Involving Porphyrins and Phthalocyanines

Sergeeva, N. N., Senge, M. O., Photochemical Transformations Involving Porphyrins and Phthalocyanines. In: CRC Handbook of Organic Photochemistry and Photobiology, (Griesbeck, A., Oelgemöller, M., Ghetti, F., eds.), CRC Press, Boca Raton, ISBN 9781439811818, pp. 831-876.

Photochemistry of the porphyrins and their relatives has been largely inspired by photosynthetic processes in nature. As a result of this, most current studies generally utilize the chemistry of magnesium and zinc porphyrin analogues. Especially, magnesium tetrapyrrole chelates, i.e. magnesium porphyrins and phthalocyanines have found wide interest.

https://dx.doi.org/10.1201/b12252-35

Adsorption of 5,10,15,20-tetrakis (4-bromophenyl)porphyrin on germanium(001)

Berner, N. C.; Sergeeva, Y. N.; Sergeeva, N. N.; Senge, M. O.; Cafolla, A. A.; McGovern, I. T., Adsorption of 5,10,15,20-tetrakis (4-bromophenyl)porphyrin on germanium(001), Phys. Status Solidi C, 2012, 9, 6, 1404— 1407.

A comparative study of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin and 5,10,15,20-tetraphenylporphyrin molecules adsorbed on the Ge(001) surface, using scanning tunnelling microscopy and photoemission spectroscopy, reveals that the bromine substituents influence the adsorption mechanism significantly.

https://dx.doi.org/10.1002/pssc.201100650

Control of the axial coordination of a surface-confined manganese(III) porphyrin complex.

Beggan, J. P., Krasnikov, S. A., Sergeeva, N. N., Senge, M. O., Cafolla, A. A., Control of the axial coordination of a surface-confined manganese(III) porphyrin complex, Nanotechnology, 2012, 23, 235606 (10pp)

The organization and thermal lability of chloro(5,10,15,20-tetraphenylporphyrinato)manganese(III) (Cl-MnTPP) molecules on the Ag(111) surface have been investigated under ultra-high vacuum conditions, using scanning tunnelling microscopy, low energy electron diffraction and x-ray photoelectron spectroscopy. The findings reveal the epitaxial nature of the molecule—substrate interface, and moreover, offer a valuable insight into the latent coordination properties of surface-confined metalloporphyrins.

https://dx.doi.org/10.1088/0957-4484/23/23/235606

Lead structures for applications in photodynamic therapy. Part 4. mTHPC — A drug on its way from second to third generation photosensitizer?

Senge, M. O., Lead structures for applications in photodynamic therapy. Part 4. mTHPC — A drug on its way from second to third generation photosensitizer?, Photodiagn. Photodyn. Ther., 2012, 9, 2, 170-179.

5,10,15,20-Tetrakis(3-hydroxyphenyl)chlorin (mTHPC, Temoporfin) is a widely investigated second generation photosensitizer. Its initial use in solution form (Foscan (R)) is now complemented by nanoformulations (Fospeg (R), Foslip (R)) and new chemical derivatives related to the basic hydroxyphenylporphyrin framework. Advances in formulation, chemical modifications and targeting strategies open the way for third generation photosensitizers and give an illustrative example for the developmental process of new photoactive drugs.

https://dx.doi.org/10.1016/j.pdpdt.2011.10.001

Organische Chemie 2011

Beuerle, F., Krüger, A., Lehmann, M., Bach, T., Beifuss, U., Müller, T. J. J., Senge, M. O., Giernoth, R., Ditrich, K., Paradies, J., Muniz, K., Straub, B. F., Schreiner, P. R., Schröder, D., Lindel, T., Pietruszka, J., Soffing, C., Pfau, R., Breinbauer, R., Sewald, N., Weinhold, E., Biskup, M. B., Dräger, G., Arenz, C., Andexer, J., Müller, M., von Deyn, W., Newton, T., Rheinheimer, J., Muhle-Goll, C., Luy, B. and Bräse, S., Organische Chemie 2011, Nachr. Chem., 2012, 60, 265—299.

Organische Solarzellen — Origami-Techniken — Photoschaltbare Organokatalysatoren — Fluorierungen — Spaltung von Ameisensäure — Klick-Chemie an RNA

https://dx.doi.org/10.1515/nachrchem.2012.60.3.265

Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED

Murphy, B. E., Krasnikov, S. A., Cafolla, A. A., Sergeeva, N. N., Vinogradov, N. A., Beggan, J. P., Lübben, O., Senge, M. O., Shvets, I. V., Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED, J. Phys.: Condens. Matter., 2012, 24, 045005 (6pp)

The room temperature self-assembly and ordering of (5,15-diphenylporphyrinato)nickel(II) (NiDPP) on the Ag(111) and Ag/Si(111)-(√3 × √3)R30° surfaces have been investigated using scanning tunnelling microscopy and low-energy electron diffraction. The self-assembled structures and lattice parameters of the NiDPP monolayer are shown to be extremely dependent on the reactivity of the substrate, and probable molecular binding sites are proposed.

https://dx.doi.org/10.1088/0953-8984/24/4/045005

5,10-A2B2-Type meso-Substituted Porphyrins—A Unique Class of Porphyrins with a Realigned Dipole Moment.

Senge, M. O., Ryppa, C., Fazekas, M., Zawadzka, M., Dahms, K., 5,10-A2B2-Type meso-Substituted Porphyrins—A Unique Class of Porphyrins with a Realigned Dipole Moment, Chem. Eur. J., 2011, 17, 48, 13562-13573.

Current applications in porphyrin chemistry require the use of unsymmetrically substituted porphyrins. Many current industrial interests in optics and biomedicine require systems with either push—pull (electron-donating and -withdrawing groups) or amphiphilic systems (hydrophobic and hydrophilic groups). In this context we present the class of 5,10-A2B2-type porphyrins for which two different substituents are positioned in diagonally opposite meso positions.

https://dx.doi.org/10.1002/chem.201101934

Synthesis and evaluation of the europiumIII and zincII complexes as luminescent bioprobes in high content cell-imaging analysis

Sergeeva, N. N., Donnier-Marechal, M., Vaz, G., Davies, A. M., Senge, M. O., Synthesis and evaluation of the europiumIII and zincII complexes as luminescent bioprobes in high content cell-imaging analysis, J. Inorg. Biochem., 2011, 105, 12, 1589-1595

Novel phenanthroline derivatives and their europium(III) and zinc(II) complexes have been prepared in up to 92%. In contrast to the stable zinc complexes, the europium compounds exhibit a strong luminescence in THF solution. However, quenching of the emission is observed in DMSO indicating complete dissociation of the complexes back to free ligands in this solvent.

https://dx.doi.org/10.1016/j.jinorgbio.2011.08.023

Evidence for the formation of an intermediate complex in the direct metalation of tetra(4-bromophenyl)-porphyrin on the Cu(111) surface.

Doyle, C. M., Krasnikov, S. A., Sergeeva, N. N., Preobrajenski, A. B., Vinogradov, N. A., Sergeeva, Y. N., Senge, M. O., Cafolla, A. A., Evidence for the formation of an intermediate complex in the direct metalation of tetra(4-bromophenyl)-porphyrin on the Cu(111) surface, Chem. Commun., 2011, 47, 12134-12136.

A strong molecule—surface interaction between free-base-tetra(4-bromophenyl)-porphyrin and Cu(111) results in a distortion of both the molecule and the underlying copper surface in the vicinity of the molecule. This in turn leads to the formation of an intermediate complex due to bonding between the iminic nitrogens and surface copper atoms.

https://dx.doi.org/10.1039/C1CC15241F

Lead Structures for Applications in Photodynamic Therapy. Part 3. Temoporfin (Foscan(R), 5,10,15,20-Tetra(m-hydroxyphenyl)chlorin)—A Second-generation Photosensitizer

Senge, M. O., Brandt, J. C., Lead Structures for Applications in Photodynamic Therapy. Part 3. Temoporfin (Foscan(R), 5,10,15,20-Tetra(m-hydroxyphenyl)chlorin)—A Second-generation Photosensitizer, Photochem. Photobiol., 2011, 87, 6, 1240-1296.

This review traces the development and study of the second-generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin through to its acceptance and clinical use in modern photodynamic (cancer) therapy. The literature has been covered up to early 2011.

https://dx.doi.org/10.1111/j.1751-1097.2011.00986.x

Conformational control of cofactors in nature—functional tetrapyrrole conformations in the photosynthetic reaction centers of purple bacteria.

MacGowan, S. A., Senge, M. O., Conformational control of cofactors in nature—functional tetrapyrrole conformations in the photosynthetic reaction centers of purple bacteria, Chem. Commun., 2011, 47, 11621-11623.

Chemically identical tetrapyrrole cofactors such as hemes and chlorophylls participate in functionally diverse biological roles. An analysis of the available protein structural data for the bacteriochlorophylls in the photosynthetic reaction center gives statistically reliable evidence of the hypothesis that the protein induced cofactor conformation is a modulator of the bio-molecular function of each reaction center. The results serve as a general model to illustrate conformational control of tetrapyrrole cofactors in other proteins.

https://dx.doi.org/10.1039/C1CC14686F

Synthesis of Unsymmetrically meso-Substituted Porphyrins

Plunkett, S., Senge, M. O., Synthesis of Unsymmetrically meso-Substituted Porphyrins, ECS Trans., 2011, 35, 25, 147-157.

The continued development of new medicinal and industrial uses of highly substituted porphyrins, especially in the fields of photodynamic therapy, nonlinear optics and electron transfer systems, has led to a resurgent interest in developing new methodologies for porphyrin synthesis. The porphyrins in question, so called ABCD-type porphyrins, have mixed meso substituents, making them highly unsymmetric and thus not synthetically available through classical condensation routes.

https://dx.doi.org/10.1149/1.3655520

Synthesis of Unsymmetrical meso-Substituted Porphyrins. 2. Porphyrin Dimers and Arrays.

Ryan, A., Gehrold, A., Perusitti, R., Pintea, M., Fazekas, M., Locos, O. B., Blaikie, F., Senge, M. O., Synthesis of Unsymmetrical meso-Substituted Porphyrins. 2. Porphyrin Dimers and Arrays, Eur. J. Org. Chem., 2011, 2011, 29, 5817-5844

Application of contemporary synthetic methods using organolithium and Pd-catalyzed C—C coupling reactions allows the synthesis of unsymmetric ADCD-type porphyrin dimers and arrays for optical applications.

https://dx.doi.org/10.1002/ejoc.201100642

Synthesis of Unsymmetrical meso-Substituted Porphyrins, 1. 5,15-A2B2- and 5,15-A2BC-Type Porphyrins with Donor and Acceptor Groups for Use in Nonlinear Optics and Photodynamic Therapy

Senge, M. O., Fazekas, M., Pintea, M., Zawadzka, M., Blau, W. J., Synthesis of Unsymmetrical meso-Substituted Porphyrins, 1. 5,15-A2B2- and 5,15-A2BC-Type Porphyrins with Donor and Acceptor Groups for Use in Nonlinear Optics and Photodynamic Therapy, Eur. J. Org. Chem., 2011, 2011, 29, 5797-5816.

The synthesis and characterization of a range of A2B2- and A2BC-type porphyrins indicates that the former are better candidates as optical limiters in nonlinear optics.

https://dx.doi.org/10.1002/ejoc.20110064

Carbazole-linked porphyrin dimers for organic light emitting diodes: synthesis and initial photophysical studies

Ryan, A., Tuffy, B., Horn, S., Blau, W. J., Senge, M. O., Carbazole-linked porphyrin dimers for organic light emitting diodes: synthesis and initial photophysical studies, Tetrahedron, 2011, 67, 43, 8248-8254

Carbazole linked porphyrin dimers were synthesized in good yields via stepwise Suzuki coupling reactions using bromoporphyrins and borylated carbazoles as the precursors, the latter of which were synthesized via known procedures from biphenyl derivatives. For comparative purposes porphyrin—carbazole monomers were synthesized.

https://dx.doi.org/10.1016/j.tet.2011.08.096

Bridging the Gap between Porphyrins and Porphycenes: Substituent-Position-Sensitive Tautomerism and Photophysics in meso-Diphenyloctaethylporphyrins.

Gawinkowski, S., Orzanowska, G., Izdebska, K., Senge, M. O., Waluk, J., Bridging the Gap between Porphyrins and Porphycenes: Substituent-Position-Sensitive Tautomerism and Photophysics in meso-Diphenyloctaethylporphyrins, Chem. Eur. J., 2011, 17, 36, 10039 - 10049.

2,3,7,8,12,13,17,18-Octaethyl-5,15-diphenylporphyrin (1) is characterized by an inner cavity with a rectangular shape and small NHef;N distances. It resembles porphycene, which is a constitutional isomer of porphyrin known for its strong intramolecular hydrogen bonds and rapid tautomerization.

https://dx.doi.org/10.1002/chem.201100902

Molecular Engineering of Nonplanar Porphyrin and Carbon Nanotube Assemblies: A Linear and Nonlinear Spectroscopic and Modeling Study.

Ní Mhuircheartaigh, É. M., Giordani S., MacKernan, D., King, S. M., Rickard, D., Val Verde, L. M., Senge, M. O., Blau, W. J., Molecular Engineering of Nonplanar Porphyrin and Carbon Nanotube Assemblies: A Linear and Nonlinear Spectroscopic and Modeling Study, J. Nanotechnol., 2011, 2011, Article ID 745202 (12 pp.)

The importance of molecular conformation to the nature and strength of noncovalent interactions existing between a series of increasingly nonplanar tetraphenylporphyrin (TPP) derivatives and carbon nanotubes was systematically investigated experimentally in solution using a range of linear and nonlinear optical techniques. Additional complementary molecular dynamics studies were found to support the experimental observations. Convincing evidence of binding between single walled nanotubes (SWNTs) and some of these porphyrins was discovered, and a nonplanar macrocycle conformation was found to increase the likelihood of noncovalent binding onto nanotubes. Nonlinear optical studies showed that the optical limiting behavior of the TPP derivatives deteriorated with increasing porphyrin nonplanarity, but that formation of nanotube composites dramatically improved the optical limiting properties of all molecules studied. It was also found that the significant photoluminescence quenching behavior reported in the literature for such porphyrin/SWNT composites is at least partly caused by photoluminescence and excitation self-absorption and is, therefore, an artifact of the system.

https://dx.doi.org/10.1155/2011/745202

Simple but powerful: Phenanthroline-based small molecules for cellular imaging and cancer screening.

Sergeeva, N. N., Donnier-Marechal, M., Vaz, G. M., Davies, A. M., Senge, M. O., Simple but powerful: Phenanthroline-based small molecules for cellular imaging and cancer screening, Bioorg. Med. Chem. Lett., 2011, 21, 15, 4385—4388.

A two-step synthetic procedure gives highly fluorescent phenanthroline molecular probes. The compounds localize in the endoplasmic reticulum and their potential as bioactive probes was evaluated. The materials are quickly taken up by living cells within 5 min. Preliminary in vitro studies have shown that these compounds are selective to esophageal cancer cells and can be used as selective markers in intracellular cancer diagnostics. The materials show a remarkable cytotoxicity towards cancer cells vs normal as 7-1.

https://dx.doi.org/10.1016/j.bmcl.2011.06.051

(2,3,7,8,12,13,17,18-Octaethyl-5-phenyl-porphyrinato)platinum(II)

Senge, M. O., Richter, J., (2,3,7,8,12,13,17,18-Octaethyl-5-phenylporphyrinato)platinum(II), Acta Cryst., 2011, E67, m1077

The title compound, [Pt(C42H48N4)], was obtained through metallation of the corresponding free base with PtCl2, followed by crystallization from methylene chloride/methanol. The molecule exhibits an almost planar macrocycle with an average deviation of the 24 macrocyclic atoms from their least-squares plane ([Delta]24) of 0.04 Å and an average Pt-N bond length of 2.022 Å. Despite the unsymmetrical substitution pattern, there is no significant difference between distortion of the geometry at the phenyl substituted meso position and those of unsubstituted meso positions.

https://dx.doi.org/10.1107/S1600536811026882

Synthesis of ferrocenyl porphyrins via Suzuki coupling and their photophysical properties.

Bakar, M. A., Sergeeva, N. N., Juillard, T., Senge, M. O., Synthesis of ferrocenyl porphyrins via Suzuki coupling and their photophysical properties, Organometallics, 2011, 30, 11, 3225—3228.

In order to improve the synthetic access to ferrocene porphyrin type electron transfer compounds, meso-ferrocenyl-appended porphyrins and bisporphyrins were prepared using Suzuki coupling reactions of borylated porphyrins with appropriate ferrocene precursors. The fluorescence lifetimes of all ferrocene porphyrin compounds are between 7.4 and 10.3 ns.

https://dx.doi.org/10.1021/om200137p

Synthesis and Crystal Structure of a Meso-Meso Directly Linked Bisporphyrin

Senge, M. O., Pintea, M., Ryan, A. A., Synthesis and Crystal Structure of a Meso-Meso Directly Linked Bisporphyrin, Z. Naturforsch., 2011, 66b, 6, 553—558.

We report the synthesis and characterization of a meso-meso directly linked bisporphyrin 6 bearing both alkyl and aryl residues. Its oxidative fusing results in the corresponding meso-meso Β-Β,Β-Β- linked bisporphyrin. The first crystal structure analysis of a meso-meso directly linked porphyrin dimer (6) has shown the inequivalency of the two porphyrin units with regard to the macrocycle conformation. Quite distinct mixings of distortion modes were observed for the two aromatic macro- cycles.

https://dx.doi.org/10.1515/znb-2011-0601

Organische Chemie 2010

Bräse, S., Würthner, F., Krüger, A., Lehmann, M., Bach, T., Beifuss, U., Karapetyan, G., Müller, T. J. J., Senge, M. O., Giemoth, R., Ditrich, K., Oestreich, M., Muniz, K., Straub, B. F., Winkler, M., Schreiner, P. R., Schröder, D., Lindel, T., Bielitza, M., Pietruszka, J., Pfau, R., von Deyn, W., Newton, T., Rheinheimer, J., Breinbauer, R., Sewald, N., Weinhold, E., Biskup, M. B., Dräger, G., Arenz, C., Hüttel, W., Müller, M. and Gschwind, R., Organische Chemie 2010, Nachr. Chem., 2011, 59, 254—283.

Die Highlights des Jahres: Funktionswerkstoffe für Solarzellen — Funktionalisierte Graphenbausteine — Kupfer in Kreuzkupplungen — Nobelpreis für Palladium-Chemie — Palau′amin — AAT-Bausteine für die Zuckerchemie.

https://dx.doi.org/10.1515/NACHRCHEM.2011.59.3.254

Extrovertierte Verwirrung — Linus Pauling, Melvin Calvin und Porphyrinisomere

Senge, M. O., Extrovertierte Verwirrung — Linus Pauling, Melvin Calvin und Porphyrinisomere, Angew. Chem., 2011, 123, 19, 4360-4365

Porphyrine mögen verwirrt sein, aber nicht Linus Pauling oder Melvin Calvin — Calvin schlug 1943 ″Carboporphyrine″ vor, und Pauling, dessen Portrait hier gezeigt ist, untersuchte 1944 die Existenz und Stabilität solch fundamentaler Porphyrine. Was er ″Isoporphyrine″ mit ″extrovertierten Pyrrolringen″ nannte, wird heute als ″N-confused″ (N-invertierte) Porphyrine bezeichnet. 1994 wurden sie schließlich von Furuta, Latos-Grażyński et al. nachgewiesen.

https://dx.doi.org/10.1002/ange.201003660

Extroverted Confusion — Linus Pauling, Melvin Calvin and Porphyrin Isomers

Senge, M. O., Extroverted confusion - Linus pauling, Melvin Calvin, and porphyrin isomers, Angew. Chem. Int. Ed., 2011, 50, 19, 4272-4277

Porphyrins may be confused, but Linus Pauling and Melvin Calvin were not! Calvin proposed "carboporphyrins" in 1943 and, unbeknownst to contemporary science, Pauling contemplated the existence and stability of such fundamental porphyrin isomers in 1944. What he called "isoporphyrins" with "extroverted pyrrole rings", nowadays called N-confused porphyrins, were discovered 50 years later in 1994 by Furuta and Latos-Grażyński et al.

https://dx.doi.org/10.1002/anie.201003660

Formation of Extended Covalently Bonded Ni Porphyrin Networks on the Au(111) Surface

Krasnikov, S. A., Doyle, C. M., Sergeeva, N. N., Preobrajenski, A. B., Vinogradov, N. A., Sergeeva, Y. N., Zakharov, A. A., Senge, M. O. and Cafolla, A. A., Formation of Extended Covalently Bonded Ni Porphyrin Networks on the Au(111) Surface, Nano Res., 2011, 4, 4, 376—384

The growth and ordering of {5,10,15,20-tetrakis(4-bromophenyl)porphyrinato}nickel(II) (NiTBrPP) molecules on the Au(111) surface have been investigated using scanning tunnelling microscopy, X-ray absorption, core-level photoemission, and microbeam low-energy electron diffraction. When deposited onto the substrate at room temperature, the NiTBrPP forms a well-ordered close-packed molecular layer in which the molecules have a flat orientation with the porphyrin macrocycle plane lying parallel to the substrate. Annealing of the NiTBrPP layer on the Au(111) surface at 525 K leads to dissociation of bromine from the porphyrin followed by the formation of covalent bonds between the phenyl substituents of the porphyrin. This results in the formation of continuous covalently bonded porphyrin networks, which are stable up to 800 K and can be recovered after exposure to ambient conditions. By controlling the experimental conditions, a robust, extended porphyrin network can be prepared on the Au(111) surface that has many potential applications such as protective coatings, in sensing or as a host structure for molecules and clusters.

https://dx.doi.org/10.1007/s12274-010-0092-7

Silyl Nitronate 1,3-Dipolar Cycloaddition Reactions with meso-Tetraarylporphyrins

Ebrahim, M. M., Moreau, M., Senge, M. O., Silyl Nitronate 1,3-Dipolar Cycloaddition Reactions with meso-Tetraarylporphyrins, 2011, 83, 3, 627-630

Isoxazoline-fused chlorins were obtained in moderate yields from the reaction of silyl nitronates and 5,10,15,20-tetra(pentafluorophenyl)porphyrin in toluene at 85 °C.

https://dx.doi.org/10.3987/COM-10-12125

Nanodrug applications in photodynamic therapy

Paszko, E., Ehrhardt, C., Senge, M. O., Kelleher, D. P., Reynolds, J. V., Nanodrug applications in photodynamic therapy, Photodiagn. Photodyn. Ther., 2011, 8, 1, 14-29

Photodynamic therapy (PDT) has developed over last century and is now becoming a more widely used medical tool having gained regulatory approval for the treatment of various diseases such as cancer and macular degeneration. It is a two-step technique in which the delivery of a photosensitizing drug is followed by the irradiation of light. Activated photosensitizers transfer energy to molecular oxygen which results in the generation of reactive oxygen species which in turn cause cells apoptosis or necrosis. Although this modality has significantly improved the quality of life and survival time for many cancer patients it still offers significant potential for further improvement. In addition to the development of new PDT drugs, the use of nanosized carriers for photosensitizers is a promising approach which might improve the efficiency of photodynamic activity and which can overcome many side effects associated with classic photodynamic therapy. This review aims at highlighting the different types of nanomedical approaches currently used in PDT and outlines future trends and limitations of nanodelivery of photosensitizers.

https://dx.doi.org/10.1016/j.pdpdt.2010.12.001

Stirring the porphyrin alphabet soup — functionalization reactions for porphyrins

Senge, M. O., Stirring the porphyrin alphabet soup—functionalization reactions for porphyrins, Chem. Commun., 2011, 47, 1943-1960

Advances in the synthesis of unsymmetrically meso substituted porphyrins are based on the development of new total syntheses and porphyrin functionalization methods. These methods have replaced earlier mixed condensation reactions and give synthetic access to almost any desired meso-substituted porphyrin. They include the complete series of porphyrin homologues and regioisomers of the Ax-series with either alkyl or aryl residues, and numerous examples of ABCD-type chromophores. The syntheses are based on a combination of classic functionalization reactions, the use of organolithium reagents in SNAr reactions, and organometallic reactions with Pd, Ni, Cr, Ru, B, and Sn catalysis. This feature article gives an account of our work in the past decade to develop synthetic methods for the Ax- and ABCD-type porphyrins and their use as optical materials and photosensitizers.

https://dx.doi.org/10.1039/C0CC03984E

{rac-5-[Methoxy(phenyl)methyl]-10,20-diphenylporphyrinato}nickel(II)

Senge, M. O. and Dahms, K., {rac-5-[Methoxy(phenyl)methyl]-10,20-diphenylporphyrinato}nickel(II), Acta Cryst., 2011, E67, m265

The title compound, [Ni(C40H28N4O)], was obtained from a Grignard reaction of the respective formylporphyrin to yield {5-[hydroxy(phenyl)methyl]-10,20-diphenylporphyrinato}nickel(II), followed by crystallization from methylene chloride/methanol. The molecule exhibits a ruffled macrocycle with an average deviation of the 24 macrocycle atoms from their least-squares plane ([Delta]24) of 0.26 Å and an average Ni-N bond length of 1.931 (2) Å. In line with the asymmetrical substituent pattern, the degree of distortion is slightly larger at point of attachment of the methoxy(phenyl)methyl residue than at the unsubstituted meso position. The methoxy group attached to the chiral C atom is disordered in a 0.534 (4):0.466 (4) ratio.

https://dx.doi.org/10.1107/S1600536811002960

Synthesis and ligand binding properties of triptycene-linked porphyrin arrays

Finnigan, E. M., Rein, R., Solladié, N., Dahms, K., Götz, D. C., Bringmann, G. and Senge, M. O., Synthesis and ligand binding properties of triptycene-linked porphyrin arrays, Tetrahedron, 2011, 67, 6, 1126-1134

Multiporphyrin arrays are a complex class of molecules with numerous potential applications in energy transfer, photomedicine, and light harvesting. We have developed a facile/versatile route to a class of triptycene-linked..

https://dx.doi.org/10.1016/j.tet.2010.12.025

(5-tert-Butylporphyrinato) copper (II), a nonplanar porphyrin with only one sterically demanding meso residue

Senge, M. O., (5-tert-Butylporphyrinato) copper (II), a nonplanar porphyrin with only one sterically demanding meso residue, Acta Cryst., 2011, C67, m39-m42

The title compound, [Cu(C24H20N4)], is a rare example of a porphyrin carrying only one substituent. Its crystal structure exhibits two molecules in the asymmetric unit. The bulky meso tert-butyl residue gives rise to a nonplanar macrocycle with significant ruf and sad distortions.

https://dx.doi.org/10.1107/S0108270111000904

The Structural Chemistry of Isolated Chlorophylls

Senge, M. O. and MacGowan, S. A., The Structural Chemistry of Isolated Chlorophylls, In: Handbook of Porphyrin Science, Kadish, K. M., Smith, K. M. and Guilard, R. (Eds.), World Scientific/Imperial College Press, Singapore, ISBN 978-981-4280-16-7, 2010, 13, 253-297

Chlorophylls are often termed the ″pigments of life″ and are the primary photosynthetic pigments in nature. They are green colored macrocyclic pigments and the term chlorophyll, coined by Berzelius in 1838, is derived from Greek roots..

https://dx.doi.org/10.1142/9789814322386_0013

Anthracenylporphyrins

Davis, M., Senge, M. O. and Locos, O. B., Anthracenylporphyrins, Zeitschrift für Naturforschung, 2011, 65b, 1472-1484, Listed in Cheminform, 2011, 42, 14, doi: 10.1002/chin.201114126(2010):

We report the synthesis and characterization of meso-anthracenylporphyrins with zinc and nickel metal centers. A variety of novel aryl and alky meso substituted anthracenylporphyrins were synthesized..

https://dx.doi.org/(empty)

Porphyrin (porphine)—A neglected parent compound with potential

Senge, M. O. and Davis, M., Porphyrin (porphine)—A neglected parent compound with potential, J. Porphyrins Phthalocyanines, 2010, 14, 07, 557-567, Listed in Cheminform, 2011, 42, 11, doi: 10.1002/chin.201111261

Porphine is the parent compound of a family of biologically and chemically relevant compounds called porphyrins. The potential of these compounds is enormous and it would be advantageous to use the porphine (porphyrin) unit as a building block for..

https://dx.doi.org/10.1142/S1088424610002495

Covalently bonded porphyrin networks studied by x-ray absorption and photoemission

Krasnikov, S. A., Doyle, C. M., Preobrajenski, A. B., Sergeeva, N. N., Vinogradov, N. A., Sergeeva, Y. N., Senge, M. O. and Cafolla, A. A., Covalently bonded porphyrin networks studied by X-ray absorption and photoemission, MAX-lab Activity Report, 2009, 396-397

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https://dx.doi.org/(empty)

Ni porphyrins and N-confused porphyrin: electronic structure studied by X-ray absorption

Krasnikov, S. A., Vinogradov, A. S., Sergeeva, N. N., Preobrajenski, A. B., Vinogradov, N. A., Sergeeva, Y. N., Senge, M. O. and Cafolla, A. A., Ni porphyrins and N-confused porphyrin: electronic structure studied by X-ray absorption, MAX-lab Activity Report, 2009, 398-399

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https://dx.doi.org/(empty)

Correlation of photophysical parameters with macrocycle distortion in porphyrins with graded degree of saddle distortion

Röder, B., Büchner, M., Rückmann, I. and Senge, M. O., Correlation of photophysical parameters with macrocycle distortion in porphyrins with graded degree of saddle distortion, Photochem. Photobiol. Sci., 2010, 9, 8, 1152-1158

Different porphyrin conformations are believed to play a role in controlling the cofactor properties in natural tetrapyrrole-protein complexes. In order to study the correlation between macrocycle nonplanarity and physicochemical properties in detail..

https://dx.doi.org/10.1039/C0PP00107D

Self-assembled rows of Ni porphyrin dimers on the Ag(111) surface

Krasnikov, S. A., Sergeeva, N. N., Sergeeva, Y. N., Senge, M. O. and Cafolla, A. A., Self-assembled rows of Ni porphyrin dimers on the Ag (111) surface, Phys. Chem. Chem. Phys., 2010, 12, 25, 6666-6671

The growth and ordering of 5-(10,15,20-triphenylporphyrinatonickel(II))dimer (NiTPP-dimer) molecules on the Ag(111) surface have been investigated using scanning tunnelling microscopy/spectroscopy (STM/STS) and low-energy electron diffraction (LEED).

https://dx.doi.org/10.1039/B921656A

(5,15-Dianthracen-9-yl-10,20-dihexylporphyrinato)nickel(II) - A planar nickel(II)porphyrin

Senge, M. O. and Davis, M., (5,15-Dianthracen-9-yl-10,20-dihexylporphyrinato)nickel(II) - A planar nickel(II)porphyrin, Acta Cryst., 2010, E66, m790

The title compound, [Ni(C60H52N4)], is an example of a meso tetrasubstituted nickel(II) porphyrin with both meso aryl and alkyl residues. The molecule exhibits a planar macrocycle..

https://dx.doi.org/10.1107/S1600536810021434

Organische Chemie 2009

Bräse, S., Würthner, F., Lehmann, M., Bach, T., Müller, T. J. J., Senge, M. O., Winkler, M., Giemoth, R., Ditrich, K., Oestreich, M., Straub, B. F., Schröder, D., Gschwind, R., Schreiner, P. R., Breinbauer, R., Sewald, N., Fischer, T., Pietruszka, J., Biskup, M. B., Arenz, C., Weinhold, E., Hüttel, W., Müller, M., Muniz, K., Draeger, G., Krüger, A., Beifuss, U., Lindel, T., Jacquot, D., Pfau, R., Biberach, H. P., Seitz, T., Kleemann, A. and von Deyn, W., Organische Chemie 2009, Nachr. Chem., 2010, 58, 267—299.

Organik von A wie Agrochemie bis Z wie (Solar-)Zelle: die ersten Cycloadditionsreaktionen angeregter Photosubstrate, das erste Beispiel eines molekularen, schwarzen Porphyrins, ein neuer Weg zur Direktoxidation von Propen zu Propenoxid, die erste Totalsynthese des Haplophytins und vieles mehr.

https://dx.doi.org/(empty)

Highly substituted 2, 3, 7, 8, 12, 13, 17, 18-octaethylporphyrins with meso aryl residues

Senge, M. O., Richter, J., Bischoff, I. and Ryan, A., Highly substituted 2, 3, 7, 8, 12, 13, 17, 18-octaethylporphyrins with meso aryl residues, Tetrahedron, 2010, 66, 19, 3508-3524

Highly substituted porphyrin-bearingmesoaryl groups are useful compounds for optical applicationsand for studies on the interrelationship between the substituent pattern, macrocycle conformation andphysical properties.

https://dx.doi.org/10.1016/j.tet.2010.03.008

Organometallic C—C Coupling Reactions for Porphyrins

Sergeeva, N. N., Senge, M. O. and Ryan, A., Organometallic C—C Coupling Reactions for Porphyrins, In: Handbook of Porphyrin Science, Kadish, K. M., Smith, K. M. and Guilard, R., (Eds.), World Scientific/Imperial College Press, Singapore, ISBN 978-981-4280-16-7, 2010, 3, 325-366

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https://dx.doi.org/10.1142/9789814280228_0012

Structural, Spectroscopic, and Anion-Binding Properties of 5,10-Porphodimethenes, An Unusual Class of Calixphyrins

Finnigan, E. M., Giordani, S., Senge, M. O. and McCabe, T., Structural, Spectroscopic, and Anion-Binding Properties of 5,10-Porphodimethenes, An Unusual Class of Calixphyrins, J. Phys. Chem. A, 2010, 114, 2464-2470

Complete spectroscopic, structural, and anion-binding properties are reported for a special class of calixphyrins, namely, 5,10-disubstituted porphodimethenes (PDMs).

https://dx.doi.org/10.1021/jp909573m

Efficient Synthesis of Glycoporphyrins by Microwave-Mediated ″Click″ Reactions

Locos, O. B., Heindl, C. C., Corral, A., Senge, M. O. and Scanlan, E. M., Efficient Synthesis of Glycoporphyrins by Microwave-Mediated ″Click″ Reactions, Eur. J. Org. Chem., 2010, 1026-1029

The CuI-catalysed Huisgen cycloaddition ″click″ reaction has been applied to the synthesis of a range of triazole-linked glycoporphyrins. The ″click″ reaction under microwaveheating conditions has been..

https://dx.doi.org/10.1002/ejoc.200901292

Synthesis of meso-Substituted ABCD-Type Porphyrins by Functionalization Reactions

Senge, M. O., Shaker, Y. M., Pintea, M., Ryppa, C., Hatscher, S. S., Ryan, A. and Sergeeva, Y., Synthesis of meso-Substituted ABCD-Type Porphyrins by Functionalization Reactions, Eur. J. Org. Chem., 2010, 2, 237-258

Considerable progress has been made in recent years in thesearch for synthetic methods leading to functionalized por-phyrins, especially for modification of either the β-or meso positions.

https://dx.doi.org/10.1002/ejoc.200901113

Photochemical Transformations Involving Copper Porphyrins and Phthalocyanines.

Sergeeva, N. N. and Senge, M. O., Photochemical Transformations Involving Copper Porphyrins and Phthalocyanines, In: The chemistry of organocopper compounds, 2009, John Wiley & Sons, Chichester, ISBN 978-0-470-77296-6, 217-245

Copper tetrapyrroles have found industrial uses for oil desulfurization, as photoconducting agents in photocopiers, deodorants, germicides, optical computer disks, semiconductor devices, photovoltaic cells, optical and electrochemical sensing, and as molecular electronic materials.

https://dx.doi.org/10.1002/9780470682531.pat0438

Synthesis and Stereochemistry of Highly Unsymmetric β, Meso-Linked Porphyrin Arrays

Götz, D. C. G., Bruhn, T., Senge, M. O. and Bringmann, G., Synthesis and Stereochemistry of Highly Unsymmetric β, Meso-Linked Porphyrin Arrays, J. Org. Chem., 2009, 74, 8005-8020, Listed in Cheminform, 2010, 41, 8, doi:10.1002/chin.201008104

Porphyrin arrays with tailor-made photophysical properties and well-defined three-dimensional geometries constitute attractive synthetic targets in porphyrin chemistry. The paper describes a variable, straightforward synthetic procedure for the construction..

https://dx.doi.org/10.1021/jo901483q

Synthesis of stannyl porphyrins and porphyrin dimers via stille coupling and their 119SN NMR and fluorescence properties

Sergeeva, N. N., Scala, A., Bakar, M. A., O′Riordan, G., O′Brien, J., Grassi, G. and Senge, M. O., Synthesis of stannyl porphyrins and porphyrin dimers via stille coupling and their 119SN NMR and fluorescence properties, J. Org. Chem., 2009, 74, 18, 7140-7147

Free base stannyl porphyrins and free base porphyrin dimers have been successfully synthesized via copper-free Stille coupling in 21-67% yields. This approach provides an access to stannyl porphyrin synthons that were previously unavailable.

https://dx.doi.org/10.1021/jo901535c

Correlation studies on structurally diverse porphyrin monomers, dimers and trimers and their nonlinear optical responses

Zawadzka, M., Wang, J., Blau, W. J. and Senge, M. O., Correlation studies on structurally diverse porphyrin monomers, dimers and trimers and their nonlinear optical responses, Chemical Physics Letters, 2009, 477, 4-6, 330—335

An investigation of the nonlinear absorption of a wide range of structurally diverse porphyrin monomers, bisporphyrins and trisporphyrins, using open Z-scan technique with 6 ns pulsed laser operating at 532 nm was carried out.

https://dx.doi.org/10.1016/j.cplett.2009.06.089

Lead structures for applications in photodynamic therapy. Part 2: Synthetic studies for photo-triggered release systems of bioconjugate porphyrin photosensitizers

Bakar, M. B., Oelgemöller, M. and Senge, M. O., Lead structures for applications in photodynamic therapy. Part 2: Synthetic studies for photo-triggered release systems of bioconjugate porphyrin photosensitizers, Tetrahedron, 2009, 65, 34, 7064-7078

Photodynamic therapy (PDT) selectivity and specificity can be improved by binding the photosensitizers to target receptors. One approach is to cross-link porphyrins to a biological target receptor via the photocleavable o-nitrobenzyl linker, where a controlled released of the porphyrin can be monitored upon irradiation.

https://dx.doi.org/10.1016/j.tet.2009.06.037

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 13. Identification of Localized Vibrational Modes in Chlorophyll a Derivatives

Senge, M. O., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 13. Identification of Localized Vibrational Modes in Chlorophyll a Derivatives, Heterocycles, 2009, 78, 6, 523-1539

A Resonance Raman investigation of chlorophyll a and meso-chlorinated and ring V hydroxylated derivatives and pheophytins reveals localized vibrational modes in the chlorophyll series. Both chlorination and hydroxylation give rise to changes in both band intensity and frequency throughout the spectrum.

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Allenylporphyrins: a new motif on the porphyrin periphery

Locos, O. B., Dahms, K. and Senge, M. O., Allenylporphyrins: a new motif on the porphyrin periphery, Tetrahedron Lett., 2009, 50, 21, 2566-2569

Palladium-catalysed Suzuki—Miyaura cross-coupling proved to be the simplest and most efficient methodfor attaching an unsubstituted allene, a novel substituent and potential functional group, to the porphyrinperiphery.

https://dx.doi.org/10.1016/j.tetlet.2009.03.097

Exploration of the reaction of potassium organotrifluoroborates with porphyrins

Horn, S., Cundell, B. and Senge, M. O., Exploration of the reaction of potassium organotrifluoroborates with porphyrins, Tetrahedron Lett., 2009, 50, 21, 2562-2565, Listed in Cheminform, 2009, 40, 35, doi: 10.1002/chin.200935117

A general method that uses potassium organotrifluoroborates in the Suzuki—Miyaura cross-couplingreaction with ring-brominated porphyrins has been investigated. The reaction conditions tolerate variousfunctional groups..

https://dx.doi.org/10.1016/j.tetlet.2009.03.098

Organische Chemie 2008

Bräse, S., Würthner, F., Tschierske, C., Bach, T., Merkul, E., Müller, T. J. J., Winkler, M., Giernoth, R., Ditrich, K., Oestreich, M., Straub, B. F., Muniz, K., Schröder, D., Gschwind, R., Schreiner, P. R., van Almsick, A., Bretschneider, T., Es-Sayed, M., Helmke, H., Thielert, W., Pfau, R., Priepke, H., Breinbauer, R., Sewald, N., Lindel, T., Fischer, T., Pietruszka, J., Dräger, G., Biskup, M. B., Wagenknecht, H.-A., Krüger, A., Weinhold, E., Hüttel, W., Müller, M., Beifuss, U. and Senge, M. O. (2009), Organische Chemie 2008, Nachr. Chem., 2009, 57, 252-277

Organische Chemie — a la carte: Lotus-Effekte mit Nanonadeln, heterolytische Aktivierung von Diwasserstoff durch frustrierte Lewis-Säure/Base-Paare, Hydroxycarben durch Blitzvakuumpyrolyse, nachwachsende Rohstoffe als Bausteine für die organische Synthese, Totalsynthese von Neopeltolid.

https://dx.doi.org/10.1002/nadc.200960646

Ni(II) porphine nanolines grown on a Ag(111) surface at room temperature.

Krasnikov, S. A., Beggan, J. P., Sergeeva, N. N., Senge, M. O. and Cafolla, A. A., Ni (II) porphine nanolines grown on a Ag (111) surface at room temperature, Nanotechnology, 2009, 20, 13, 135301

The room temperature growth and ordering of (porphyrinato)nickel (II) (or nickel (II) porphine, NiP) molecules on a Ag(111) surface have been investigated using scanning tunnelling microscopy and low-energy electron diffraction (LEED).

https://dx.doi.org/10.1088/0957-4484/20/13/135301

Synthesis, Transformations, and Comparative Studies of Porphyryl Acrylic Acids and Their Homologues.

Sergeeva, N. N., Bakar, M. B. and Senge, M. O., Synthesis, transformations, and comparative studies of porphyryl acrylic acids and their homologues, J. Org. Chem., 2009, 74, 4, 1488-1497

The reactivity of porphyryl acrylates and their homologues was studied systematically and to establish their potential as building blocks for the synthesis of novel tetrapyrroles. A new synthetic approach for multifunctional porphyrins was developed using Α,Β-unsaturated acyl porphyrins..

https://dx.doi.org/10.1021/jo8021764

Synthetic transformations of porphyrins—advances 2004-2007.

Horn, S., Dahms, K. and Senge, M.O., Synthetic transformations of porphyrins—advances 2004-2007, J. Porphyrins Phthalocyanines, 2008, 12, 10, 1053-1077, Listed in Cheminform, 2010, 41, 7, doi: 10.1002/chin.201007258

Recent developments in the synthesis and transformation of porphyrins and their derivatives are presented. In connection with the Fifth International Conference on Porphyrins and Phthalocyanines (ICPP-5) a survey of current method developments and reactivity studies is made. The review focuses on synthetic advances in porphyrin chemistry. A brief survey of important developments covers selectively the literature from 2004 to late 2007.

https://dx.doi.org/10.1142/S108842460800042X

The Intermolecular Pauson-Khand Reaction of meso-Substituted Porphyrins

Horn, S. and Senge, M. O., The Intermolecular Pauson-Khand Reaction of meso-Substituted Porphyrins, European Journal of Organic Chemistry, 2008, 29, 4881-4890

Porphyrins containing alkenyl- and alkynyl-substituents at the meso position can be used as precursors for the intermolecular Pauson-Khand reaction. A variety of cyclopentenyl-substituted porphyrins canbe synthesised in moderate to good yields.

https://dx.doi.org/10.1002/ejoc.200800488

Triptycene as a rigid, 120° orienting, three-pronged, covalent scaffold for porphyrin arrays

Dahms, K. and Senge, M. O., Triptycene as a rigid, 120° orienting, three-pronged, covalent scaffold for porphyrin arrays, Tetrahedron Lett., 2008, 49, 37, 5397-5399

The synthesis of novel porphyrin trimers covalently linked by one central, rigid triptycene unit is described. Reaction of 2,6,14-triiodotriptycene, generated in a three-step synthesis from triptycene, with borylated porphyrins under Suzuki cross-coupling conditions afforded porphyrin trimers.

https://dx.doi.org/10.1016/j.tetlet.2008.07.008

Synthesis of porphyryl boronates with (un)saturated side—chains

Sergeeva, N. N., Pablo, V. L. and Senge, M. O., Synthesis of porphyryl boronates with (un)saturated side-chains, J. Organomet. Chem., 2008, 693, 15, 2637-2640

Porphyrins with (un)saturated side—chains containing boron residues were developed as synthons for porphyrin functionalisation. Porphyrins with mono and bis-substituted unsaturated boronyl residues were prepared in good yields (52—66%) using a cross-metathesis approach in the presence of Grubbs I-generation catalysts.

https://dx.doi.org/10.1016/j.jorganchem.2008.05.006

Organische Chemie 2007

Würthner, F., Tschierske, C., Bach, T., Beifuss, U., Müller, T. J. J., Senge, M. O., Winkler, M., Giernoth, R., Ditrich, K., Oestreich, M., Bisel, P., Müller, M., Straub, B. F., Muniz, K., Heydt, H., Hartung, J., Schröder, D., Gschwind, R., Schreiner, P. R., van Almsick, A., Mansfield, D., Bretschneider, D., Es-Sayed, M., Pfau, R., Priepke, H., Breinbauer, R., Sewald, N., Lindel, T., Jacquot, T., Pietruszka, J., Dräger, G., Biskup, M. B., Weinhold, E., Wagenknecht, H.-A. and Krüger, A. (2008), Organische Chemie 2007, Nachr. Chem., 2008, 56, 269-294

Organische Chemie — bunt gemischt: Organokatalyse mit Radikalen; mesoporöse, kovalente 3D-Strukturen; provirale DNA, herausgeschnitten aus dem Genom von HIV-infizierten humanen Zellen; reversible Photoreaktionen im Einkristall, die phototaktisch reagieren, und die gelungene Totalsynthese von Azadirachtin.

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An X-ray absorption and photoemission study of the electronic structure of Ni porphyrins and Ni N-confused porphyrin

Krasnikov, S. A., Sergeeva, N. N., Brzhezinskaya, M. M., Preobrajenski, A. B., Sergeeva, Y. N., Vinogradov, N. A., Cafolla, A. A., Senge, M. O. and Vinogradov, A. S., An X-ray absorption and photoemission study of the electronic structure of Ni porphyrins and Ni N-confused porphyrin, J. Phys.: Condens. Matter, 2008, 20, 23, 235207

Investigations of chemical bonding and electronic structure features for polycrystalline (porphyrinato)nickel (II) (NiP, the simplest Ni porphyrin), (5,10,15,20-tetraphenylporphyrinato)nickel (II) (NiTPP) and (2-aza-21-carba-5,10,15,20-tetraphenylporphyrinato)nickel (II) (N-confused NiTPP, NiNCTPP) have been performed by means of high-resolution soft x-ray absorption and x-ray photoemission spectroscopy.

https://dx.doi.org/10.1088/0953-8984/20/23/235207

Photochemical transformations involving magnesium porphyrins and phthalocyanines

Sergeeva, N. N. and Senge, M. O., Photochemical transformations involving magnesium porphyrins and phthalocyanines, In: The chemistry of organomagnesium compounds, Rappoport, Z. and Marek, I. (Eds.), John Wiley & Sons, Chichester, ISBN 978-0-470-05719-3, 2008, 173, 189-218

The photochemistry of true organomagnesium compounds remains almost completely unexplored. A literature search in preparation of this work found only a few scattered examples of photochemical studies, mostly in relation to Grignard..

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Electronic structure of Ni porphyrins and Ni N-confused porphyrin: X-ray absorption and photoemission study

Krasnikov, S. A., Sergeeva, N. N., Brzhezinskaya, M. M., Preobrajenski, A. B., Sergeeva, Y. N., Vinogradov, N. A., Püttner, R., Cafolla, A. A., Senge, M. O., Vinogradov, A. S., Electronic structure of Ni porphyrins and Ni N-confused porphyrin: X-ray absorption and photoemission study, Bessy Annual Report, 2007, 158-160

Due to their unique properties 3d transition metal (TM) porphyrins are widely used in many technological applications such as sensors, pigments applications, cancer therapy, artificial photosynthesis, nonlinear optics, and nanomaterials.

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Influence of the core conformation on the NH-tautomerism in porphyrins: A study of meso-(1,3-dithian-2-yl)porphyrins.

Wacker, P.; Dahms, K.; Senge, M.O.; Kleinpeter, E. Influence of the core conformation on the NH-tautomerism in porphyrins: A study of meso-(1,3-dithian-2-yl)porphyrins. J. Org. Chem. 2008, 73, 2182—2190.

In order to investigate the mechanism of the NH-tautomerism in porphyrins, three meso-dithianyl-substituted porphyrins of different substitution pattern were studied theoretically. The corresponding trans-, cis- and saddle-point geometries were optimized with DFT methods, and the macrocyclic conformations obtained were analyzed using normal-structure- decomposition (NSD) analysis. Special attention was given to the influence of the participating out-of-plane and in-plane conformations on the NH-tautomerism, and the interplay of substituents, core conformations and energies of the transition-state structures was critically evaluated. The calculated energy barriers of the preferred pathways are compared with experimental activation enthalpies determined by variable-temperature (VT) NMR spectroscopy.

https://dx.doi.org/10.1021/jo702443x

Synthetic strategies and porphyrin building blocks for unsymmetrical multichromophores.

Fazekas, M.; Pintea, M.; Senge, M.O.; Zawadzka, M. Synthetic strategies and porphyrin building blocks for unsymmetrical multichromophores. Tetrahedron Lett. 2008, 49, 2236—2239.

A sequential use of halogenation, SNAr, Sonogashira and/or Suzuki couplings together with the use of either mono-5-, 5,15- or 5,10-di-meso-substituted porphyrins allows the facile construction of unsymmetrical porphyrin dimers and trimers with different spatial orientation. The protocols established allow a convenient entry into multichromophores suitable for application in nonlinear optics and biomedicine.

https://dx.doi.org/10.1016/j.tetlet.2008.02.029

Self-assembly of Ni(II) porphine molecules on the Ag/Si(111)-(√3 × √3)R30° surface studied by STM/STS and LEED.

Beggan, J.P.; Krasnikov, S.A.; Sergeeva, N.N.; Senge, M.O.; Cafolla, A.A. Self-assembly of Ni(II) porphine molecules on the Ag/Si(111)-(√3 × √3)R30° surface studied by STM/STS and LEED. J. Phys. Condens. Matter 2008, 20.

The room-temperature growth and ordering of (porphyrinato)nickel(II) (nickel(II) porphine, NiP) molecules on the Ag/Si(111)- surface have been investigated using scanning tunnelling microscopy/spectroscopy (STM/STS) and low-energy electron diffraction (LEED). The results indicate a well-ordered molecular layer in which the porphyrin molecules have a flat orientation with the molecular plane lying parallel to the substrate and forming a hexagonal overlayer on the surface. STM and LEED data obtained from one monolayer (ML) of the NiP on the Ag/Si(111)- surface show the formation of two well-ordered mirror domains, each rotated either clockwise or counterclockwise by 7° with respect to the substrate. A hexagonal Moiré pattern was observed for the NiP overlayer due to long-range variation in the overlayer-substrate distance. It was found that the existence of such azimuthal rotation and the Moiré pattern are caused by a lattice mismatch between the substrate and the molecular overlayer, and a corresponding model is proposed. The NiP molecules forming the second monolayer maintain the same planarity and hexagonal ordering as the first molecular layer. Scanning tunnelling spectroscopy data obtained from the NiP overlayer on the Ag/Si(111)- surface show good agreement with density functional theory calculations.

https://dx.doi.org/10.1088/0953-8984/20/01/015003

Synthesis of hydroporphyrins based on comparative studies of palladium-catalyzed and non-catalyzed approaches.

Sergeeva, N.N.; Shaker, Y.M.; Finnigan, E.M.; McCabe, T.; Senge, M.O. Synthesis of hydroporphyrins based on comparative studies of palladium-catalyzed and non-catalyzed approaches. Tetrahedron 2007, 63, 12454—12464.

Hydroporphyrins have been synthesized using both Pd-catalyzed and non-catalyzed approaches. Comparative studies of the reaction of tetrasubstituted porphyrins with organolithium reagents in the presence of and without palladium catalysts showed that depending on reagents, the catalyst structure and reactivity of the corresponding porphyrins, chlorins (Β-hydroporphyrins) and/or porphodimethenes (meso hydroporphyrins) of 5,10-type can be prepared in reasonable yields. In the absence of Pd catalysts, the formation of chlorins is predominant in the reactions with aliphatic RLi while porphodimethenes are the main products in reactions with PhLi.

https://dx.doi.org/10.1016/j.tet.2007.09.030

Nonlinear optical properties of porphyrins.

Senge, M.O.; Fazekas, M.; Notaras, E.G.A.; Blau, W.J.; Zawadzka, M.; Locos, O.B.; Mhuircheartaigh, E.M.N. Nonlinear optical properties of porphyrins. Adv. Mater. 2007, 19, 2737—2774.

Porphyrins and phthalocyanines have outstanding chemical and thermal stability. The macrocyclic structure and chemical reactivity of tetrapyrroles offers architectural flexibility and facilitates the tailoring of chemical, physical and optoelectronic parameters. The specific optical properties of the tetrapyrrole macrocycle combined with the synthetic methodologies now available and the already available theoretical and spectroscopic knowledge on their optical behavior make porphyrins a target of choice for this area.

https://dx.doi.org/10.1002/adma.200601850

Conformational landscape of meso-(1,3-dithian-2-yl)porphyrins.

Wacker, P.; Dahms, K.; Senge, M.O.; Kleinpeter, E. Conformational landscape of meso-(1,3-dithian-2-yl)porphyrins. J. Org. Chem. 2007, 72, 6224—6231.

An investigation of the conformational landscape of 1,3-dithian-2-yl bearing porphyrins and the rotational behavior of the dithianyl substituents in meso position was carried out by variable-temperature (VT) NMR spectroscopy. Additionally, theoretical results for alternative conformations and energy barriers were obtained by molecular modeling. The study revealed different NH trans tautomers with regard to the orientation of the dithianyl ligands for the free base porphyrins 1-3. Relatively ruffled porphyrin core conformations were established for the transition states of the dithianyl rotation, resulting in a lower rotational energy barrier for the nickel(II) complex 4 compared to that of the free base systems.

https://dx.doi.org/10.1021/jo0708700

Conversion of Ni(II)-Allylporphyrins to Α,Β-Unsaturated Formylporphyrins via a Nickel-Promoted Reaction.

Horn, S.; Sergeeva, N.N.; Senge, M.O. Conversion of Ni(II)-Allylporphyrins to Α,Β-Unsaturated Formylporphyrins via a Nickel-Promoted Reaction. J. Org. Chem. 2007, 72, 5414—5417.

A new route to alpha, beta-unsaturated formylporphyrins begins with the synthesis of allyl-substituted porphyrins via the Suzuki cross-coupling reaction of bromoporphyrins and allylboronic acid pinacol ester in 50-95% yield.

https://dx.doi.org/10.1021/jo070550g

Exploration of meso -Substituted Formylporphyrins and Their Grignard and Wittig Reactions.

Dahms, K.; Senge, M.O.; Bakar, M.B. Exploration of meso -Substituted Formylporphyrins and Their Grignard and Wittig Reactions. Eur. J. Org. Chem. 2007, 3833—3848.

Formylporphyrins were prepared by using either the 1,3-dithian-2-yl residue as a precursor for the CHO group or by the Vilsmeier reaction. Two synthetic routes for the introduction of the 1,2-dithian-2-yl group were explored. Furthermore, reactions of the 1,3,5-trithian-2-yl group with porphyrins were examined as well as spirobisdithiane derivatives as precursors for the ultimate assembly of porphyrin spirobisdithanyl-linked bioconjugates. The obtained formylporphyrins were reacted with organomagnesium or organophosphorus compounds. A series of hydroxyporphyrins resulting from the Grignard reaction of 5,15-substituted porphyrins were synthesised in high yields. Several porphyrins with unsaturated residues introduced by the Wittig reaction were obtained in moderate yields. The less sterically hindered 5,15-substituted porphyrins show increased reactivity and give higher yields; their reaction products are higher in stability relative to other porphyrin systems. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

https://dx.doi.org/10.1002/ejoc.200700380

N-[4-(Di-2-pyrrolylmeth-yl)phen-yl]-acetamide.

Senge, M.O. N-[4-(Di-2-pyrrolylmeth-yl)phen-yl]-acetamide. Acta Cryst. 2007, E63, o3679

The crystal structure of the title compound, C17H17N3O, shows the formation of infinite chains of molecules that are linked via hydrogen bonds involving the acetamide group. The carbonyl O atom forms hydrogen bonds with both a pyrrole NH group and another acetamide NH unit. In addition, the carbonyl O atom is involved in a weak intramolecular interaction with the neighboring aryl group, thus connecting different chains.

https://dx.doi.org/10.1107/S1600536807037385

Benzyl 4-ethyl-3-methyl-5-(phthalimidomethyl)pyrrole-2-carboxylate

Senge, M. O.; Benzyl 4-ethyl-3-methyl-5-(N-phthalimido)-methylpyrrole-2-carboxylate. Acta Cryst. 2007, E63, o3363.

The title compound, C24H22N2O4, forms weak inter- and intramolecular N—Hef;O hydrogen bonds. Additional intermolecular C—Hef;O interactions give rise to a three-dimensional network in the crystal structure.

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X-ray absorption study of electronic structure of Ni(II) phthalocyanine and porphyrins

Krasnikov, S. A.; Preobrajenski, A. B.; Sergeeva, N. N.; Brzhezinskaya, M. M.; Nersterov M. A.; Cafolla, A. A.; Senge, M. O.; Vinogradov, A. S.; X-ray absorption study of electronic structure of Ni(II) phthalocyanine and porphyrins. Bessy Annual Report 2007, 391—393.

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A2B2-type push-pull porphyrins as reverse saturable and saturable absorbers

Notaras, E.G.A.; Fazekas, M.; Doyle, J.J.; Blau, W.J.; Senge, M.O. A2B2-type push-pull porphyrins as reverse saturable and saturable absorbers. Chem. Commun. 2007, 2166—2168.

A2B2-type push-pull porphyrins with a strong intramolecular dipole moment have been prepared via Heck and Suzuki coupling reactions as novel materials for use in nonlinear optics (NLO); they display saturable (SA) and reverse saturable absorption (RSA) properties at 532 nm and their nonlinear optical response is characterized by RSA occuring at lower intensity levels whereas the onset of SA prevails at higher levels.

https://dx.doi.org/10.1039/b618996b.

Organische Chemie 2006.

Würthner, F., Tschierske, C., Kruger, A., Ditrich, K., Pfau, R., Priebke, H., Breinbauer, R., Wagenknecht, H. A., Drager, G., Kirschning, A., Seewald, N., Beifuss, U., Senge, M. O., Muller, T. J. J., Schreiner, P. R., Gschwind, R., Straub, B. F., Muniz, K., Oestreich, M., Pietruszka, J., Lindel, T., Süssmuth, R., Bisel, P., Muller, M., Weinhold, E., Jäschke, A., Albrecht, M., Bach, T., Bucher, G., Heydt, H. and Hartung, J., Organische Chemie 2006, Nachr. Chem., 2007, 55, 252—275.

Die organische Chemie zeigt einmal mehr ihre Vielseitigkeit: Stereoselektive Synthesen in ionischen Flüssigkeiten, Diels-Alder-Reaktionen in Containermolekülen, metallorganische Reaktionen mit schweren Erdalkalimetallen, eine organokatalytische Kaskade. Kohlendioxid schaltet Emulgatoren, der Naturstoff Platensimycin wirkt gegen Staphylokokken, Acetyl-CoA-Carboxylase dient als Target im Pflanzenschutz. Kristallstrukturen von Fettsäuresynthasen und einer Nicht-Häm-Eisenhalogenase erregen Aufsehen.

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Electronic structure of Ni(II) porphyrins and phthalocyanine studied by soft X-ray absorption spectroscopy

Krasnikov, S.A.; Preobrajenski, A.B.; Sergeeva, N.N.; Brzhezinskaya, M.M.; Nesterov, M.A.; Cafolla, A.A.; Senge, M.O.; Vinogradov, A.S. Electronic structure of Ni(II) porphyrins and phthalocyanine studied by soft X-ray absorption spectroscopy. Chem. Phys. 2007, 332, 318—324.

Investigations of chemical bonding and electronic structure features for polycrystalline Ni(II) phthalocyanine (NiPc), Ni(II) tetrabenzoporphyrin (NiTBP), Ni(II) 2,3,7,8,12,13,17,18-octaethylporphyrin (NiOEP), Ni(II) 5,10,15,20-tetraisobutylporphyrin (NiTiBuP), Ni(II) 5,15-diphenylporphyrin (NidPP) and Ni(II) 5,15-diisobutylporphyrin (NidiBuP) have been performed by means of high-resolution soft X-ray absorption spectroscopy.

https://dx.doi.org/10.1016/j.chemphys.2006.12.015

Metamorphosis of tetrapyrrole macrocycles.

Senge, M.O.; Sergeeva, N.N. Metamorphosis of tetrapyrrole macrocycles. Angew. Chemie - Int. Ed. 2006, 45, 7492—7495.

I don't like what I am: An example of ring-size change in tetrapyrroles is found in the ring expansion of corroles to porphyrins (see scheme). These and other recently discovered relationships between tetrapyrrole structures offer the possibility of rapid autoconversion of such macrocycles.

https://dx.doi.org/10.1002/anie.200603249.

New palladium catalysed reactions of bromoporphyrins: Synthesis and crystal structures of nickel(II) complexes of primary 5-aminoporphyrin, 5,5′-bis(porphyrinyl) secondary amine, and 5-hydroxyporphyrin.

Esdaile, L.J.; Senge, M.O.; Arnold, D.P. New palladium catalysed reactions of bromoporphyrins: Synthesis and crystal structures of nickel(II) complexes of primary 5-aminoporphyrin, 5,5′-bis(porphyrinyl) secondary amine, and 5-hydroxyporphyrin. Chem. Commun. 2006, 2, 4192—4194.

Primary aminoporphyrin, secondary bis(porphyrinyl)amine and hydroxyporphyrin complexes have been isolated and characterised both spectroscopically and crystallographically from the reaction of 5-bromo-10,15,20-triphenylporphyrinatonickel(II) with hydrazine under palladium catalysis.

https://dx.doi.org/10.1039/b608365j

Photochemical Transformations Involving Zinc Porphyrins and Phthalocyanines.

Senge, M. O.; Sergeeva, N. N. Photochemical Transformations Involving Zinc Porphyrins and Phthalocyanines. In: The chemistry of organozinc compounds, (Rappoport, Z.; Marek, I., eds.), John Wiley & Sons, Chichester, 2006, pp. 395—419.

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Ethyl 4-benzyloxycarbonyl-5-[2,2-bis(benzyloxycarbonyl)vinyl]-3-methylpyrrole-2-carboxylate

Senge, M.O.; Smith, K.M. Ethyl 4-benzyloxycarbonyl-5-[2,2-bis(benzyloxycarbonyl)vinyl]-3- methylpyrrole-2-carboxylate. Acta Crystallogr. Sect. E Struct. Reports Online 2006, 62, 4660—4662.

The crystal structure of the title compound, C34H31NO8, is stabilized by intramolecular C—HO and N—HO hydrogen bonds, intermolecular C—HO hydrogen bonds, and C—H--pi and pi—pi interactions

https://dx.doi.org/10.1107/S1600536806038359

meso-iodo- and meso-iodovinylporphyrins via organopalladium porphyrins and the crystal structure of 5-iodo-10,20-diphenylporphyrin.

Atefi, F.; Locos, O.B.; Senge, M.O.; Arnold, D.P. meso-iodo- and meso-iodovinylporphyrins via organopalladium porphyrins and the crystal structure of 5-iodo-10,20-diphenylporphyrin. J. Porphyr. Phthalocyanines 2006, 10, 176—185.

The regiospecific halogen exchange reactions of various easily accessible meso-bromoporphyrins to obtain meso-iodoporphyrins, using palladioporphyrins as intermediates, have been investigated. This one-pot methodology allows the isolation of meso-iodoporphyrins in excellent yields with short reaction times. Similarly meso-(2-bromoethenyl)porphyrins can be converted to their iodoethenyl analogues. These iodoporphyrins show great potential as starting materials for various palladium catalyzed reactions. The X-ray crystal structure of 5-iodo-10,20-diphenylporphyrin has been determined.

https://dx.doi.org/10.1142/S1088424606000211

Palladium-catalyzed reactions for the synthesis of chlorins and 5,10-porphodimethenes

Sergeeva, N.N.; Senge, M.O. Palladium-catalyzed reactions for the synthesis of chlorins and 5,10-porphodimethenes. Tetrahedron Lett. 2006, 47, 6169—6172.

The palladium-catalyzed reaction of RLi with various 5,10,15,20-tetrasubstituted porphyrins offers a convenient synthetic route to chlorins and porphodimethenes (calixphyrins). The reactions utilized various Pd catalysts and CuI and yielded either 2,3-substituted chlorins or 5,10-disubstituted porphodimethenes in yields ranging from 20-40%. The reaction of octaethylporphyrin with t-BuLi in the presence of a Pd-catalyst generated the corresponding 5,10-porphodimethene in 72% yield.

https://dx.doi.org/10.1016/j.tetlet.2006.06.166

On the Correlation Between Hydrophobicity, Liposome Binding and Cellular Uptake of Porphyrin Sensitizers

Ben-Dror, S.; Bronshtein, I.; Wiehe, A.; Röder, B.; Senge, M.O.; Ehrenberg, B. On the Correlation Between Hydrophobicity, Liposome Binding and Cellular Uptake of Porphyrin Sensitizers. Photochem. Photobiol. 2006, 82, 695.

A crucial factor in choosing a porphyrin or analogous photosensitizer for photodynamic therapy (PDT) is its ability to incorporate into the cells. For hydrophobic compounds that partition passively into the cytoplasmic membrane, a partition coefficient between an organic solvent and water, P, is one factor that could be used to predict the molecule's ability to diffuse into biomembranes. We synthesized several porphyrins, modified with two, three or four meso-substituents and studied their spectroscopic and photophysical properties.

https://dx.doi.org/10.1562/2005-09-01-ra-669.

Synthesis, Reactivity and Structure of Chlorophylls.

Senge, M. O.; Wiehe, A.; Ryppa, C. Synthesis, Reactivity and Structure of Chlorophylls. In: Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications, (Grimm, B.; Porra, R.; Rüdiger, W.; Scheer, H., eds.), Advances in Photosynthesis and Respiration, 2006, Vol. 25, Springer, Dordrecht, pp. 27—37.

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https://dx.doi.org/1-4020-4515-8.

Organische Chemie 2005.

Würthner, F., Tschierske, C., Kruger, A., Ditrich, K., Pfau, R., Priepke, H., Breinbauer, R., Wagenknecht, H. A., Drager, G., Kirschning, A., Seewald, N., Beifuss, U., Senge, M. O., Muller, T. J. J., Schreiner, P. R., Gschwind, R., Straub, B. F., Muniz, K., Oestreich, M., Pietruszka, J., Lindel, T., Süssmuth, R., Bisel, P., Mulller, M., Weinhold, E., Jäschke, A., Albrecht, M., Bach, T., Bucher, G., Heydt, H. and Hartung, J., Organische Chemie 2005, Nachr. Chem., 2006, 54, 241—264.

Die enantioselektive Synthese bleibt zentrales Thema in metallorganischen, metallfreien and bioorganischen Transformationen sowie in der industriellen organischen Chemie. Glanzpunkte zielmolekülorientierter Synthesechemie waren ein Zugang zu C60, die Route zum Diazonamid A und die Totalsynthese von Vinblastin. Mit ″Pyrrolysin″ wurde die 22. proteinogene Aminosäure entdeckt. Trotz der immer höheren Zahl an Testsubstanzen besteht in der medizinischen Chemie ein Engpass an klinisch erfolgreichen Wirkstoffen.

https://dx.doi.org/(empty)

Adding Color to Green Chemistry? An Overview of Fundamentals and Potential of Chlorophylls.

Senge, M. O.; Richter, J. Adding Color to Green Chemistry? An Overview of Fundamentals and Potential of Chlorophylls. In: Biorefineries — Industrial Processes and Products. Status Quo and Future Directions, (Kamm, B.; Gruber, P. R.; Kamm, M., eds.),2006, Vol. 2, Wiley-VCH Verlag, Weinheim, 325—343.

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https://dx.doi.org/3-527-31027-4

Exercises in molecular gymnastics - Bending, stretching and twisting porphyrins.

Senge, M.O. Exercises in molecular gymnastics - Bending, stretching and twisting porphyrins. Chem. Commun. 2006, 243—256.

The functional versatility of tetrapyrroles as natural cofactors is related to their conformational flexibility where manipulation of the macrocycle conformation allows a fine-tuning of their physicochemical properties. This feature article gives a personal account of the synthesis and solid state structural characterization of highly substituted, non-planar porphyrins. Their conformational analysis identifies sterically strained tetrapyrroles as a versatile class of biomimetic compounds with tailor-made properties.

https://dx.doi.org/10.1039/b511389j

Nucleophilic substitution as a tool for the synthesis of unsymmetrical porphyrins.

Senge, M.O. Nucleophilic substitution as a tool for the synthesis of unsymmetrical porphyrins. Acc. Chem. Res. 2005, 38, 733—743.

Porphyrins readily undergo SNAr reactions with organolithium reagents, preferentially at the meso-positions. The reaction is highly versatile as it is accomplished with both metal complexes and free-base porphyrins in good yields and high regioselectivity. It can be used in sequence for the introduction of up to four different meso-substituents and is the first general method for the direct introduction of functional groups into unactivated porphyrins, including porphine. Depending on the porphyrin, the structure of the anionic intermediate, or the reaction conditions, this method also allows trapping of the intermediary anion with electrophiles, transformation into meso-meso-linked bisporphyrins, synthesis of phlorins or porphodimethenes, and Β-addition to yield hydroporphyrins.

https://dx.doi.org/10.1021/ar0500012

One-pot synthesis of A2BC—type free base porphyrins.

Shaker, Y. M.; Senge, M. O. One-pot synthesis of A2BC—type free base porphyrins. Heterocycles , 2005, 65, 2441—2450.

Treatment of 5,15-diarylporphyrins with a combination of organolithium and alkyl iodide reagents followed by hydrolysis with water and oxidation with DDQ gives convenient access to A2BC-type meso-tetrasubstituted free base porphyrins in a one-pot synthesis. Key intermediates are mesomeric phlorin- and porphodimethene-type anions, the latter one being able to react with electrophiles under thermodynamic control.

https://dx.doi.org/10.3987/COM-05-10506

Hydrogen-bonding patterns in six derivatives of 2,4-dimethylpyrrole

Senge, M.O.; Smith, K.M. Hydrogen-bonding patterns in six derivatives of 2,4-dimethyl-pyrrole. Acta Crystallogr. Sect. C , 2005, 61, o537--o541.

The crystal and molecular structures of 4-ethyl-3,5-dimethylpyrrole-2-carbaldehyde, C10H15NO, (I), benzyl 3,5-dimethylpyrrole-2-carboxylate, C14H15NO2, (II), benzyl 4-acetyl-3,5-dimethylpyrrole-2-carboxylate, C16H17NO3, (III), dimethyl 3,5-dimethylpyrrole-2,4-dicarboxylate, C10H13NO4, (IV), 4-ethyl-3,5-dimethyl-2-(p-tosylacetyl)pyrrole, C17H21NO3S, (V), and ethyl 4-(2-ethoxycarbonyl-2-hydroxyacryloyl)-3,5-dimethylpyrrole-2-carboxylate, C15H19NO6, (VI), were determined at 130 K.

https://dx.doi.org/10.1107/S0108270105023991

Synthesis of mono- And disubstituted porphyrins: A- and 5,10-A 2-type systems

Ryppa, C.; Senge, M.O.; Hatscher, S.S.; Kleinpeter, E.; Wacker, P.; Schilde, U.; Wiehe, A. Synthesis of mono- And disubstituted porphyrins: A- and 5,10-A 2-type systems. Chem. Eur. J. 2005, 11, 3427—3442.

General syntheses have been developed for meso-substituted porphyrins with one or two substituents in the 5,10-positions and no Β substituents. 5-Substituted porphyrins with only one meso substituent are easily prepared by an acid-catalyzed condensation of dipyrromethane, pyrrole-2-carbaldehyde, and an appropriate aldehyde using a "[2+1+1]" approach. Similarly, 5,10-disubstituted porphyrins are accessible by simple condensation of unsubstituted tripyrrane with pyrrole and various aldehydes using a "[3+1]" approach.

https://dx.doi.org/10.1002/chem.200500001

Lead structures for applications in photodynamic therapy. Part 1: Synthesis and variation of m-THPC (Temoporfin) related amphiphilic A2BC-type porphyrins.

Wiehe, A.; Shaker, Y.M.; Brandt, J.C.; Mebs, S.; Senge, M.O. Lead structures for applications in photodynamic therapy. Part 1: Synthesis and variation of m-THPC (Temoporfin) related amphiphilic A2BC-type porphyrins. Tetrahedron, 2005, 61, 5535—5564

Photodynamic therapy (PDT) is a developing modality for the treatment of certain tumorous and other diseases. Considerable progress has been made in recent years in the search for new photosensitizers, in particular elucidating the role of localization of the photosensitizer. Known successful photosensitizers of the tetrapyrrole type are amphiphilic molecules, preferably localizing in cellular membrane structures. Thus, the quest for new photosensitizers requires the synthesis of unsymmetrically substituted (amphiphilic) tetrapyrroles. In this article, we describe strategies for the de novo synthesis of amphiphilic tetrapyrroles using a 3-hydroxyphenyl substituted tetrapyrrolic system (Temoporfin) as the lead structure.

https://dx.doi.org/10.1016/j.tet.2005.03.086

Synthesis of benzoporphyrins with one or two meso-substituents via substitution reactions.

Senge, M. O.; Bischoff, I. Synthesis of benzoporphyrins with one or two meso-substituents via substitution reactions. Heterocycles, 2005, 65, 879—886.

Reaction of either free base benzoporphyrin, its zinc(II) complex or Β-bicyclo(2,2,2)octeno appended precursor porphyrins with LiR reagents gave an entry into mono- and soluble di-meso-substituted benzoporphyrins.

https://dx.doi.org/10.3987/COM-05-10323

Hydrogen Bonding and Conformation of 5-Substituted Dipyrromethanes — A Solid State Study

Senge, M.O. Hydrogen Bonding and Conformation of 5-Substituted Dipyrromethanes — A Solid State Study. Heterocycles 2005, 65, 797—808.

A crystallographic study of nine different meso-substituted dipyrromethanes identifies the main types of intra- and intermolecular hydrogen bonding pattern in this class of porphyrin building blocks. Most compounds form similar hydrogen-bonded dimers in the crystal but distinct differences in the dipyrromethane conformations are observed in dependence on the type of the meso substituent.

https://dx.doi.org/10.3987/COM-05-10322

Organic Chemistry 2004 | Organische Chemie 2004.

Brückner, R., Würthner, F., Tschierske, C., Krüger, A., Herges, R., Ditrich, K., Pfau, R., Priepke, H., Beifuss, U., Bräse, S., Senge, M.O., Müller, T. J. J., Bach, T., Heydt, H., Hartung, J., Schreiner, P. R., Gschwind, R., Plattner, D. A., Brönstrup, M., Goldfuß, B., Gansäuer, A., Oestreich, M., Pietruszka, J., Lindel, T., Müller, M., Weinhold, E., Hausch, F., Jäschke, A. and Albrecht, M., Organic chemistry 2004 | Organische chemie 2004, Nachr. Chem., 2005, 53, 251-272.

Produktiv und ideenreich wie eh und je präsentiert sich die organische Chemie: Topologien für das Lehrbuch (Möbius-Aromat, Borromäische Ringe), Zweistufensynthesen von Aldohexosen mit Organokatalyse, Br/MgCl-Austausch als Zugang zu funktionalisierten Arylgrignard-Verbindungen, die Totalsynthese des Naturstoffs Azaspirazid oder Pentalactame aus einer DNA-gesteuert synthetisierten Bibliothek funktionalisierter Tetrapeptide…

https://dx.doi.org/(empty)

Dibenzyl 5-(2-chloroethyl)-3,7-diethyl-2,8-di-methyldipyrromethane-1,9-dicarboxylate.

Senge, M.O. Dibenzyl 5-(2-chloroethyl)-3,7-diethyl-2,8-di-methyldipyrromethane-1,9-dicarboxylate. Acta Crystallogr. Sect. E Struct. Reports Online 2005, 61, 506—508.

The structure of the title compound [systematic name: dibenzyl 3,3′-diethyl-4,4′-dimethyl-2,2′-(3-chloropropane-1,1-diyl) dipyrrole-5,5′-dicarboxylate], C33H37ClN2O4, was determined by single-crystal X-ray diffraction at 130 K. In the crystal structure, the compound forms hydrogen-bonded dimers. The two pyrrole H atoms are bonded to one carbonyl O atom of a symmetry-related molecule. Additional, weaker, C-Hef;O interactions further stabilize the dimers. The two pyrrole rings are inclined to one another by 63.57 (7)°.

https://dx.doi.org/10.1107/S160053680500245X

Chloro(2,3,7,8,12,13,17,18-octaethylporphyrinato)iron(III)

Senge, M.O. Chloro(2,3,7,8,12,13,17,18-octaethylporphyrinato)iron(III). Acta Crystallogr. Sect. E Struct. Reports Online 2005, 61, 399—400.

The molecular structure of the title compound, [Fe(C36H44N4)Cl], was determined by single-crystal X-ray diffraction at 130 K. The compound is characterized by an average Fe-N bond length of 2.071 (2) Å and an Fe-Cl bond length of 2.231 (1) Å.

https://dx.doi.org/10.1107/S1600536805002461.

Influence of substitutions on asymmetric dihydroxychlorins with regard to intracellular uptake, subcellular localization and photosensitization of Jurkat cells.

Rancan, F., Wiehe, A., Nobel, M., Senge, M. O., Al Omari, S., Bohm, F., John, M. and Roder, B., Influence of substitutions on asymmetric dihydroxychlorins with regard to intracellular uptake, subcellular localization and photosensitization of Jurkat cells, Z. J. Photochem. Photobiol. B, Biol., 2005, 78, 17-28.

The search for new efficient sensitizers for photodynamic therapy (PDT) points to improve photophysical properties like absorption in the red region and singlet oxygen quantum yield as well as to control the localization of the sensitizer within the tumour cell. Depending on their physicochemical properties and their uptake mechanism, sensitizers can reach different intracellular concentrations and localize in different subcellular compartments.

https://dx.doi.org/10.1016/j.jphotobiol.2004.08.010

Synthetic transformations of porphyrins — Advances 2002-2004

Senge, M. O. and Richter, J., Synthetic transformations of porphyrins — Advances 2002-2004, J. Porphyr. Phthalocyanines, 2004, 8, 934-953.

Contemporary methods for the modification of porphyrins are presented. In association with the Third International Conference on Porphyrins and Phthalocyanines (ICPP-3) a survey of current method developments and reactivity studies is made. The review focuses on synthetic transformations of porphyrins currently in use for various applications and on functional group transformations. A brief survey of important developments covers selectively the literature from late 2001 to early 2004.

https://dx.doi.org/10.1142/S1088424604000313

The dithianyl group as a synthon in porphyrin chemistry: Condensation reactions and preparation of formylporphyrins under basic conditions.

Senge, M. O., Hatscher, S. S., Wiehe, A., Dahms, K. and Kelling, A., The dithianyl group as a synthon in porphyrin chemistry: Condensation reactions and preparation of formylporphyrins under basic conditions, J. Am. Chem. Soc., 2004, 126, 13634-13635.

Vilsmeier formylation is one of the most widely used substitution reactions for the functionalization of porphyrins. However, its utility is limited by the electrophilic/acidic reaction conditions, deactivation of the aromatic system and regiochemical problems, the requirement for metal complexes and necessity for subsequent demetalation under harsh conditions, and low functional group tolerance.

https://dx.doi.org/10.1021/ja045223u

Trendbericht Organische Chemie 2003

Würthner, F., Krüger, A., Herges, S., Ditrich, K., Pripke, H., Pfau, R., Bräse, S., Kirschning, A., Sewald, N., Senge, M. O., Müller, T. J. J., Bach, T., Heydt, H., Hartung, J., Schreiner, P. R., Gschwind, R., Plattner, D. A., Goldfuß, B., Goldfuß, B., Gansäuer, A., Oestreich, M., Pietruszka, J., Lindel, T.; Süßmuth, R., Müller, M., Weinhold, E., Jäschke, A., Albrecht, M. and Beifuß, U., Trendbericht Organische Chemie 2003, Nachr. Chem., 2004, 52, 267-291.

Katalyse, Peptidchemie und Nanostrukturen bargen einige der Perlen aus organisch-chemischer Forschung: Kombinatorische Ligandenoptimierung, H-Verbrückung einzähniger zu zweizähnigen Liganden, Diels-Alderase- Aktivitäten im molekularen Detail, ein 36-er Peptid zur Behandlung von Aids, totalsynthetisch in 106 Stufen hergestellt, ein 21-er Peptid mit Lasso-Struktur, Kohlenstoffnanoröhren ah elektromechanische Lager.

https://dx.doi.org/10.1002/nadc.20040520308

Oxasmaragdyrin—Ferrocene and Oxacorrole—Ferrocene Conjugates: Synthesis, Structure, and Nonlinear Properties.

Venkatraman, S., Kumar, R., Sankar, J., Chandrashekar, T. K., Sendhil, K., Vijayan C., Kelling, A. and Senge, M. O. Oxasmaragdyrin—Ferrocene and Oxacorrole—Ferrocene Conjugates: Synthesis, Structure, and Nonlinear Properties., Chem. Eur. J., 2004, 10, 1423-1432.

Ferrocenyl macrocyclic conjugates involving 22Π oxasmaragdyrins and 18Π oxacorroles have been synthesized and characterized. The direct covalent linkage of the ferrocenyl moiety to the meso position of the macrocycle is achieved by simple oxidative coupling of appropriate precursors with trifluoroacetic acid as catalyst. The electronic coupling between the ferrocenyl moiety and the macrocyclic Π system is apparent from: a) the red shifts (293—718 cm—1) of the Soret and Q-bands in the electronic absorption spectra of ferrocenyl conjugates; b) the shift of oxidation potentials (50—130 mV) of both the ferrocene and the corrole rings to the positive potentials; and c) considerable shortening of the CC bond which connects the ferrocene and the meso-carbon atom of the macrocycle.

https://dx.doi.org/10.1002/chem.200305558

The meso-b-linkage as structural motif in porphyrin-based donor-acceptor compounds.

Senge, M. O., Rossler, B., von Gersdorff, J., Schafer, A. and Kurreck, H., The meso-b-linkage as structural motif in porphyrin-based donor-acceptor compounds., Tetrahedron Lett., 2004, 45, 3363-3367.

Synthetic strategies for using the meso—Β-linkage as a structural motif in electron transfer mimics have been tested. Exploratory syntheses of directly meso—Β-linked bis- and trisporphyrins and the first representative X-ray structure of a meso—Β-linked bisporphyrins are reported. The structure reveals a unique form of intramolecular Π—Π stabilization between one porphyrin and a meso-aryl substituent in a second porphyrin unit that accounts for the stability of different atropisomers in trimers.

https://dx.doi.org/10.1016/j.tetlet.2004.03.027

Dodecasubstituted Porphyrins — An Easily Accessible Type of Dendritic Porphyrins.

Ryppa, C. and Senge, M. O., Dodecasubstituted Porphyrins — An Easily Accessible Type of Dendritic Porphyrins, Heterocycles, 2004, 63, 505-508.

Dodecasubstituted dendritic porphyrins with nonplanar macrocycles were synthesized by a convergent approach via Lindsey condensation reactions in good yields.

https://dx.doi.org/10.3987/COM-03-9962

Interplay of Axial Ligation, Hydrogen Bonding, Self-Assembly, and Conformational Landscapes in High-Spin Ni(II) Porphyrins.

Barkigia, K. M., Renner, M. W., Senge, M. O. and Fajer, J. Interplay of Axial Ligation, Hydrogen Bonding, Self-Assembly, and Conformational Landscapes in High-Spin Ni(II) Porphyrins, J. Phys. Chem. B, 2004, 108, 2173-2180.

The molecular structures of four bis-ligated high-spin Ni(II) complexes of the sterically crowded, nonplanar 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetranitroporphyrin (NiOETNP) are reported. The ligands are imidazole (Im), imidazole plus 2-methylimidazole (2-MeIm) in the crystal lattice, 1-methylimidazole (1-MeIm), and 2,1,3-benzoselenadiazole (BSeD). Extensive intermolecular hydrogen bonding is observed in the three imidazole-ligated structures consisting of NH···O and CH···O bonding from the imidazoles to neighboring nitro groups and of NH···N interactions to a nearby 2-MeIm. The different modes of hydrogen bonding, typical of those frequently observed in proteins, mediate the self-assembly of discrete porphyrin dimers as well as more extensive two- and three-dimensional arrays. Only the bis-BSeD complex remains monomeric.

https://dx.doi.org/10.1021/jp036398d

SNAr reactions of b-substituted porphyrins and the synthesis of meso substituted tetrabenzoporphyrins.

Senge, M. O. and Bischoff, I., SNAr reactions of b-substituted porphyrins and the synthesis of meso substituted tetrabenzoporphyrins, Tetrahedron Lett., 2004, 45, 1647-1650.

Reaction of 2,3,7,8,12,13,17,18-octaethylporphyrin with LiR reagents containing functional groups readily yields meso substituted derivatives suitable for further transformations with residues such as —p-C6H5Br, —p-C6H5—CCH, —p-C6H5—NH2 or —(CH2)3—CHCH2. Similar reactions of tetrabenzoporphyrin with alkyllithium reagents afforded the first entry into meso mono- and dialkylsubstituted tetrabenzoporphyrins while reaction of bicyclo[2.2.2]oct-type masked isoindole precursors with LiR followed by in situ retro-Diels—Alder reaction also afforded the 5-phenyl and 5,10-diphenyltetrabenzoporphyrins in high purity.

https://dx.doi.org/10.1016/j.tetlet.2003.12.121

Synthesis and electrochemical investigation of covalently linked porphyrin dimers containing a b-brominated subunit. Crystal structure of H2[TriPP-TPP(Br8)]H2.

Ou, Z., Tagliatesta, P., Senge, M. O., Shao, J. and Kadish, K. M., Synthesis and electrochemical investigation of covalently linked porphyrin dimers containing a b-brominated subunit. Crystal structure of H2[TriPP-TPP(Br8)]H2, J. Porphyr. Phthalocyanines, 2003, 7, 595-609.

Ten meso-tetraphenylporphyrin-type heterodimers containing a partly or completely Β-brominated subunit were synthesized and characterized by UV-visible spectroscopy, cyclic voltammetry and spectroelectrochemistry, showing the presence of low electronic interactions between the two subunits. The investigated compounds are represented as M[(tripp-tpp(Br4)]M and M[tripp-tpp(Br8)]M (M = 2H, Zn, Ni, Co and Cu) where tripp-tpp(Br4) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,12,13-tetrabromoporphyrinyl)]-benzene and tripptpp( Br8) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,7,8,12,13,17,18- octabromoporphyrinyl)]-benzene. One of the synthesized dimers, H2[tripp-tpp(Br8)]H2, was characterized by a single-crystal X-ray investigation. Copyright (C) 2003 Society of Porphyrins & Phthalocyanines.

https://dx.doi.org/10.1142/S1088424603000756

Trendbericht Organische Chemie 2002

Würthner, F., Herges, S., Sewald, N., Senge, M. O., Bach, T., Gottwald, T., Kopf, T., Spehar, K., Hartung, J., Plattner, D., Gansäuer, A., Oestreich, M., Brückner, R., Pietruszka, J., Süßmuth, R., Müller, M., Weinhold, E., Jäschke, A., Albrecht, M., Priepke, H., Roth, G., Ditrich, K., Ernst, A., Wortmann, L., Bohlmann, R., Wenz, M. and Jaroch, S., Trendbericht Organische Chemie 2002, Nachr. Chem., 2003, 51, 286-315.

Die enantioselektive Synthese bleibt zentrales Thema in metallorganischen, metallfreien and bioorganischen Transformationen sowie in der industriellen organischen Chemie. Glanzpunkte zielmolekülorientierter Synthesechemie waren ein Zugang zu C60, die Route zum Diazonamid A und die Totalsynthese von Vinblastin. Mit ″Pyrrolysin″ wurde die 22. proteinogene Aminosäure entdeckt. Trotz der immer höheren Zahl an Testsubstanzen besteht in der medizinischen Chemie ein Engpass an klinisch erfolgreichen Wirkstoffen.

https://dx.doi.org/10.1002/nadc.20030510309

Core-modified Hexaphyrins; characterization of two and four ring inverted 26 p aromatic macrocycles.

Rath, H., Ahand, V. G., Sankar, J., Venkatraman, S., Chandrashekar, T. K., Joshi, B. S., Khetrapal, C. L., Schilde, U. and Senge, M. O., Core-modified Hexaphyrins; characterization of two and four ring inverted 26 p aromatic macrocycles, Org. Lett., 2003, 5, 3531-3533.

Synthesis and structural characterization of aromatic core-modified 26 Π hexaphyrin analogues are reported.

https://dx.doi.org/10.1021/ol035408q

Synthetic Potential and Limitations of o-Quinones as Acceptor Groups in Electron Transfer Compounds.

Senge, M. O., Hatscher, S., Okten, Z. and Speck, M. Synthetic Potential and Limitations of o-Quinones as Acceptor Groups in Electron Transfer Compounds, Tetrahedron Lett., 2003, 44, 4463-4466.

Syntheses have been developed that utilize o-quinones as suitable acceptor groups in porphyrin-based diad and triad donor—acceptor compounds. While alkyl groups at the 3,6-position of the quinone stabilize the target compounds, oxidative degradation and dimerization reactions can occur depending on the type of the porphyrin and quinone part. Thus, care has to be taken in choosing the right quinone and porphyrin component when designing novel electron transfer compounds.

https://dx.doi.org/10.1016/S0040-4039(03)01028-1

Synthetic Access to 5,10-Disubstituted Porphyrins.

Hatscher, S. and Senge, M. O., Synthetic Access to 5,10-Disubstituted Porphyrins., Tetrahedron Lett., 2003, 44, 157-160.

A simple acid-catalyzed condensation of unsubstituted tripyrranes with pyrrole and various aldehydes affords 5,10-disubstituted-Β-unsubstituted porphyrins by the ′3+1′ approach in low to moderate yields. A complementary synthesis of similar compounds involves reaction of unsubstituted porphyrin (porphine) with organolithium reagents in good yields. The title porphyrins were prepared either by condensation via a ′3+1′ approach or by reaction of porphine with organolithium reagents.

https://dx.doi.org/10.1016/S0040-4039(02)02475-9

A Practical Synthesis of meso-Monosubstituted, b-Unsubstituted Porphyrins.

Wiehe, A., Ryppa, C. and Senge, M. O. A Practical Synthesis of meso-Monosubstituted, b-Unsubstituted Porphyrins, Org. Lett., 2002, 4, 3807-3809.

A simple straightforward synthesis for meso-monosubstituted, Β-unsubstituted porphyrins is reported. Porphyrins of this type are easily prepared by condensation of dipyrromethane, pyrrole-2-carbaldehyde, and the desired aromatic or aliphatic aldehyde. The method can be used for a variety of functional groups with yields between 2 and 12%. In most cases, the 5,15-disubstituted porphyrin is obtained as a second product but can be removed easily.

https://dx.doi.org/10.1021/ol0265867

Isomeric porphyrin phenanthrene quinones: Synthesis, NMR spectroscopy, electrochemical properties, and in situ EPR/ENDOR studies of the o-semiquinone anion radicals.

Speck, M., Niethammer, D. and Senge, M. O. Isomeric porphyrin phenanthrene quinones: Synthesis, NMR spectroscopy, electrochemical properties, and in situ EPR/ENDOR studies of the o-semiquinone anion radicals, J. Chem. Soc. Perkin Trans. II, 2002, 455-462.

Porphyrin quinones are attractive model compounds for mimicking natural electron transfer processes. While the overwhelming majority of studies have been performed with porphyrin p-quinones the isomeric porphyrin o-quinones have been mostly neglected. Using phenanthrene-9,10-quinones as the acceptor component we have prepared several porphyrin o-quinones (1, 2, 5, 6) and show that a facile and simple variation of ΔGET can be achieved by using the in situ formed semiquinones for metal chelatization.

https://dx.doi.org/10.1039/B110273G

Mechanistic Studies on the Nucleophilic Reaction of Porphyrins with Organolithium Reagents.

Feng, X., Bischoff, I. and Senge, M. O., Mechanistic Studies on the Nucleophilic Reaction of Porphyrins with Organolithium Reagents, J. Org. Chem., 2001, 66, 8693-8700.

Porphyrins react readily with organolithium reagents under substitution of free meso positions. As this method has proven to be very versatile for the preparation of a wide range of meso substituted porphyrins, a mechanistic study of the reaction was undertaken using 5,15-diaryl- and dialkyl substituted porphyrins, 2,3,7,8,12,13,17,18-octaethylporphyrin, and the respective nickel(II) complexes.

https://dx.doi.org/10.1021/jo010559x

PDT-Related Photophysical Properties of Conformationally Distorted Palladium(II) Porphyrins.

Stollberg, H., Runge, S., Paul, A., Wiehe, A., Senge, M. O. and Röder, B., PDT-Related Photophysical Properties of Conformationally Distorted Palladium(II) Porphyrins, J. Porphyr. Phthalocyanines, 2001, 5, 853-860.

The photodynamic therapy (PDT) related photophysical properties of five palladium(II) porphyrins with increasing steric demand of the meso-substituents were investigated by steady state and time-resolved absorption and luminescence spectroscopy. The steric strain of the meso-substituents is reflected in a bathochromic shift of the B-band in the absorption spectra. In contrast to free-base porphyrins, the palladium(II) complexes exhibit only a very weak fluorescence with ΦFl ∼10—4.

https://dx.doi.org/10.1002/jpp.553

Electron Donor-Acceptor Compounds. Exploiting the Triptycene Geometry for the Synthesis of Porphyrin-Quinone Diads, Triads, and a Tetrad.

Wiehe, A., Senge, M. O., Schäfer A.; Speck, M., Tannert, S., Kurreck, H. and Röder, B., Electron Donor-Acceptor Compounds. Exploiting the Triptycene Geometry for the Synthesis of Porphyrin-Quinone Diads, Triads, and a Tetrad, Tetrahedron, 2001, 57, 10089-10110.

Rigidly and covalently linked porphyrin quinones are well established as model compounds for studying photo-induced electron transfer (PET) reactions like those occurring during the primary processes of photosynthesis. In this context, the synthesis of a number of porphyrin quinones is reported in which one or two porphyrin electron donors are connected to either one or two quinone electron acceptors, resulting in diad, triad, and tetrad model systems, respectively.

https://dx.doi.org/10.1016/S0040-4020(01)01052-3

Hydrophilicity versus Hydrophobicity - Varying the Amphiphilic Structure of Porphyrins Related to the Photosensitizer m-THPC

Wiehe, A., Simonenko, E. J., Senge, M. O., Röder, B., Hydrophilicity versus Hydrophobicity - Varying the Amphiphilic Structure of Porphyrins Related to the Photosensitizer m-THPC, J. Porphyr. Phthalocyanines, 2001, 5, 758-761.

A total of 21 different porphyrins, some of them closely related to the photosensitizer meta-tetra-hydroxyphenylchlorin (m-THPC) with a varied degree of hydrophilic/lipophilic substitution were synthesized em-ploying conventional porphyrin condensation procedures and modern functionalization via organolithium reagents. For 14 of them, the photodynamic therapy (PDT) related photophysical properties were determined in isotropic solution and in liposome membrane-model systems. The photophysical data indicate that the localization of m-THPC may be fine-tuned by carefully changing the substitution pattern.

https://dx.doi.org/10.1002/jpp.389

One-pot synthesis of functionalized, highly substituted porphodimethenes.

Bischoff, I., Feng, X. and Senge, M. O., One-pot synthesis of functionalized, highly substituted porphodimethenes, Tetrahedron, 2001 57, 5573-5583.

Treatment of nickel(II)complexes of 2,3,7,8,12,13,17,18-octaethylporphyrin with a combination of organolithium and alkyl iodide reagents gives convenient access to di-, tri-and tetra-meso-substituted porphodimethenes with different substituent patterns in a one-pot synthesis. The substituents can possess a variety of functional groups like -I, COOEt and CN.

https://dx.doi.org/10.1016/S0040-4020(01)00486-0

2,3,7,8,12,13,17,18-Octachloroporphyrin.

Senge, M. O., Flogel, O. and Ruhlandt-Senge, K., 2,3,7,8,12,13,17,18-Octachloroporphyrin, J. Porphyr. Phthalocyanines, 2001, 5, 503-506.

Synthesis of 3,4-dichloropyrrole and reaction with formaldehyde and p-toluene sulfonic acid catalysis, followed by oxidation with Ag2O allows a low yield entry into 2,3,7,8,12,13,17,18-octachloroporphyrin. The extremely low solubility of the free base requires work-up in the presence of metallo acetates for in situ formation of metal complexes. Utilizing this method, zinc(II) and nickel(II) complexes of the title compound were prepared as the first examples of a novel porphyrin class bearing only Β-halogeno substituents. In addition, the first crystal structure of a 3,4-dihalopyrrole, 3,4-dichloropyrrole, is reported.

https://dx.doi.org/10.1002/jpp.353

An Efficient Synthesis of Highly Functionalized Asymmetric Porphyrins with Organolithium Reagents.

Senge, M. O., An Efficient Synthesis of Highly Functionalized Asymmetric Porphyrins with Organolithium Reagents, J. Chem. Soc. Perkin Trans. I, 2001, 1030-1038.

Functionalized tri- (A2B-type) and tetra- (A2BC-type) meso-substituted asymmetric porphyrins bearing highly reactive centers like -NH2, -OH, -C[triple bond, length as m-dash]CH, -CHO in substituents at the meso positions were synthesized in good yields via the reaction of 5,15-diphenylporphyrin with corresponding functionalized organolithium reagents. Through further transformation other functional groups like carboxylate, iodophenyl, thiocarboxylate, tertiary amines and quaternary ammonium salts are easily available.

https://dx.doi.org/10.1039/B100012H

Regioselective Synthesis of Conformationally Designed Porphyrins with Mixed meso-Substituent Types and Distortion Modes

Senge, M. O. and Bischoff, I., Regioselective Synthesis of Conformationally Designed Porphyrins with Mixed meso-Substituent Types and Distortion Modes, Eur. J. Org. Chem., 2001, 1735-1751.

Porphyrins can be substituted easily and in high yield at the meso positions by using organolithium reagents. When S4-symmetric porphyrins such as 2,3,7,8,12,13,17,18-octaethylporphyrins are used as starting materials, it is possible to perform four such substitution reactions in sequence, resulting in the formation of nona-, deca-, undeca-, and dodecasubstituted porphyrins. Introduction of the first and second meso substituents can be achieved in almost quantitative yields, while the third and fourth meso substitutions proceed in about 50—70% yield with the remainder of the starting material being converted into stable porphomethenes.

https://dx.doi.org/10.1002/1099-0690(200105)2001:9<1735::AID-EJOC1735>3.0.CO;2-6

Sodium Etiobilirubin-IVΓ-C10-sulfonate: A Highly Solvated Bile Pigment Structure Containing Two Different Non-ridge-tile Conformers in the Unit Cell.

Senge, M. O., Ma, J. S. and McDonagh, A. F., Sodium Etiobilirubin-IVΓ-C10-sulfonate: A Highly Solvated Bile Pigment Structure Containing Two Different Non-ridge-tile Conformers in the Unit Cell. Bioorg. Med. Chem. Lett., 2001 11, 875-878.

The crystal structure of the title compound is the first example of a bilirubin existing in both extended and cyclic conformations and the first bile pigment structure showing two markedly different conformations in the unit cell. In contrast to previous rubin structures the dipyrrinone rings are twisted out of planarity in both conformers.

https://dx.doi.org/10.1016/S0960-894X(01)00106-8

The Malaria Pigment Haemozoin — A Focal Point of Action for Antimalarial Drugs.

Senge, M. O. and Hatscher, S., The Malaria Pigment Haemozoin — A Focal Point of Action for Antimalarial Drugs, Z. Naturforsch. B, 2000 1, 247-249.

A dimer of two iron protoporphyrins was found in the recently determined structure of the malaria pigment haemozoin (see schematic picture). Together with novel data on antimalarial drugs that act by preventing the formation of these dimers, this result provides impetus for the design of novel antimalarial drugs. These are desperately needed because malaria continues to be a major health problem worldwide, especially since resistance towards antimalarial drugs is increasing.

https://dx.doi.org/10.1002/1439-7633(20001117)1:4<247::AID-CBIC247>3.0.CO;2-O

Identification of stable porphomethenes and porphodimethenes from the reaction of sterically hindered aldehydes with pyrrole.

Senge, M. O., Runge, S.; Speck, M. and Ruhlandt-Senge, K., Identification of stable porphomethenes and porphodimethenes from the reaction of sterically hindered aldehydes with pyrrole, Tetrahedron, 2000 56, 8927-8932.

Use of pivalaldehyde in mixed acid-catalyzed condensations of an aryl aldehyde with pyrrole allows the isolation and structural characterization of stable porphomethenes (5,10,15,22-tetrahydroporphyrins) and porphodimethenes (both 5,10- and 5,15-diphydroporphyrins) as intermediates of porphyrin synthesis.

https://dx.doi.org/10.1016/S0040-4020(00)00823-1

Regioselective Reaction of 5,15-Disubstituted Porphyrins with Organolithium Reagents — Synthetic Access to 5,10,15-Trisubstituted Porphyrins and Directly meso-meso-Linked Bisporphyrins.

Senge, M. O. and Feng, X., Regioselective Reaction of 5,15-Disubstituted Porphyrins with Organolithium Reagents — Synthetic Access to 5,10,15-Trisubstituted Porphyrins and Directly meso-meso-Linked Bisporphyrins, J. Chem. Soc. Perkin Trans. I, 2000 , 3615-3621.

The reaction of organolithium reagents with 5,15-disubstituted porphyrins, followed by hydrolysis of the intermediate anion to give a porphodimethene and oxidation with DDQ allows the facile preparation of 5,10,15-tri- and 5,10,15,20-tetrasubstituted porphyrins with mixed meso substituent types. Easily available 5,15-disubstituted porphyrins react almost quantitatively with sterically undemanding organolithium reagents (PhLi, BuLi) to give the respective 5,10,15-trisubstituted porphyrins (A2B-type). When bulkier reagents are used (e.g. Bus or But) the number and yield of side products increases considerably.

https://dx.doi.org/10.1039/B005411I

The Reaction of Porphyrins with Organolithium Reagents.

Senge, M. O., Kalisch, W. W. and Bischoff, I. A., The Reaction of Porphyrins with Organolithium Reagents., Chem. Eur. J., 2000 6, 2721—2738.

Porphyrins react readily with organolithium reagents, preferentially in the meso positions. The overall reaction is a nucleophilic substitution and proceeds via initial reaction of the organic nucleophile with a meso carbon yielding an anionic species which is hydrolyzed to a porphodimethene (5,15-dihydroporphyrin), formally constituting an addition reaction to two Cm positions.

https://dx.doi.org/10.1002/1521-3765(20000804)6:15<2721::AID-CHEM2721>3.0.CO;2-Z

Structural Diversity in Rubyrins: X-ray Structural Characterization of Planar and Inverted Rubyrins.

Narayanan, S. J., Srinivasan, A., Sridevi, B., Chandrashekar T. K., Senge, M. O., Sugiura, K.-i. and Sakata, Y.A Structural Diversity in Rubyrins: X-ray Structural Characterization of Planar and Inverted Rubyrins, Eur. J. Org. Chem., 2000 , 2357—2360.

Meso aryl rubyrins exhibit three different structures. A planar (7) and two unusual inverted structures (8 and 9) have been characterised by X-ray and NMR spectroscopy.

https://dx.doi.org/10.1002/1099-0690(200007)2000:13<2357::AID-EJOC2357>3.0.CO;2-V

Porphyrin-o-Quinones as Models for Natural Electron Transfer Systems and Catecholase Reactions.

Speck, M., Kurreck, H. and Senge, M. O., Porphyrin-o-Quinones as Models for Natural Electron Transfer Systems and Catecholase Reactions, Eur. J. Org. Chem., 2000 ,2303-2314.

Various porphyrin-o-quinones 1—8 were prepared as model compounds for electron transfer reactions. The synthesis of these compounds could only be accomplished by using o-quinone components stabilized by sterically demanding substituents in the o,o′-positions and by using protected catechol aldehydes for the initial porphyrin condensation step. The stability of the target compounds strongly depends on the steric influence of substituents on the o-quinone, which are necessary to stabilize the o-quinones.

https://dx.doi.org/10.1002/1099-0690(200006)2000:12<2303::AID-EJOC2303>3.0.CO;2-U

Syntheses and Spectroscopic Studies of Novel Chlorins with Fused Quinoxaline or Benzimidazole Ring Systems and the Related Dimers with Extended Conjugation

Kozyrev, A. N., Suresh, V., Suresh, D., Senge, M. O., Shibata, M. A., Dougherty, T. J. and Pandey, R. K., Syntheses and Spectroscopic Studies of Novel Chlorins with Fused Quinoxaline or Benzimidazole Ring Systems and the Related Dimers with Extended Conjugation. Tetrahedron, 2000 56, 3353-3364.

Condensation of 132-oxopyropheophorbide a 1 with various aromatic diamines under acid-catalyzed conditions afforded a series of novel chlorins with fused quinoxaline or benzimidazole polyaromatic ring systems. This methodology was extended for the preparation of laterally bridged pyropheophorbide a dimers.

https://dx.doi.org/10.1016/S0040-4020(00)00256-8

A Conformational Study of 5,10,15,20-Tetraalkyl-22H+,24H+-porphyrindiium Salts (Dication Salts)

Senge, M. O., A Conformational Study of 5,10,15,20-Tetraalkyl-22H+,24H+-porphyrindiium Salts (Dication Salts), Z. Naturforsch. B, 2000 55, 336-344.

X-ray crystallographic studies show that protonation of porphyrins with n-Bu (2), i-Pr (3) or EtPr (4) substituents leads to steric congestion of the core resulting in symmetric, saddle distorted macrocycles as evidenced by average displacements of the Cb positions from the mean plane ranging from 0.79 to 1.01 Å. The structures observed for these porphyrin diacids are very similar in distortion mode and degree of nonplanarity to 5,10,15,20-tetraaryl-22H+,24H+-porphyrindiium salts and to 2,3,7,8,12,13,17,18-octaalkyl-5,10,15,20-tetraaryl-porphyrins.

https://dx.doi.org/10.1515/znb-2000-3-417

One-pot Synthesis of Functionalized Asymmetric 5,10,15,20-Substituted Porphyrins from 5,15-Diaryl- or -Dialkylporphyrins.

Feng, X. and Senge, M. O., One-pot Synthesis of Functionalized Asymmetric 5,10,15,20-Substituted Porphyrins from 5,15-Diaryl- or -Dialkyl-porphyrins, Tetrahedron, 2000 56, 587-590.

Reaction of easily available (5,15-dialkyl/arylporphyrinato)nickel(II) with RLi under anhydrous conditions affords 5,10,15-trisubstituted porphyrin anions that can be used as in situ nucleophiles for reaction with alkyl iodide reagents. After oxidation with atmospheric oxygen, 5,10,15,20-tetrasubstituted porphyrins are obtained in good yields. This method permits introduction of all base-stable functional groups into the meso position of porphyrins.

https://dx.doi.org/10.1016/S0040-4020(99)01055-8

Molecular structure of (5,10,15,20-tetrabutyl-2,3,7,8,12,13,17,18-octaethylporphyrinato)nickel(II)—correlation of nonplanarity with frontier orbital shifts

Senge, M. O., Renner , M. W., Kallisch, W.W. and Senge, M. O., Molecular structure of (5,10,15,20-tetrabutyl-2,3,7,8,12,13,17,18-octaethylporphyrinato)nickel(II)—correlation of nonplanarity with frontier orbital shifts, J. Chem. Soc., Dalton Trans., 2000 , 381-385.

A crystal structure analysis of the title compound NiTBuOEP reveals a highly nonplanar conformation with an average deviation from planarity for the 24 macrocycle atoms of 0.462 Å and displacements of the meso carbon atoms from the 4N-plane of 1.044 Å. The average Ni—N bond distance in the crystal (1.873(3) Å) is in good agreement with the Ni—N bond distance in solution (1.87 Å) that was determined by EXAFS.

https://dx.doi.org/10.1039/A905927J

Database of Tetrapyrrole Crystal Structure Determinations.

Senge, M. O., Database of Tetrapyrrole Crystal Structure Determinations. In: The Porphyrin Handbook, (Kadish, K. M.; Smith, K. M.; Guilard, R., eds.), Vol. 10, Academic Press, San Diego, pp. 1-218. .

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https://dx.doi.org/(empty)

Highly Substituted Porphyrins. In: The Porphyrin Handbook

Senge, M. O., Highly Substituted Porphyrins. In: The Porphyrin Handbook, (Kadish, K. M.; Smith, K. M.; Guilard, R., eds.), Vol.1, Academic Press, San Diego, pp. 239-347.

The last decade has seen a renaissance in porphyrin chemistry involving such diverse fields as supramolecular chemistry, advanced biomimetic models for photosynthesis, catalysis, organometallic chemistry, and medicinal applications like photodynamic therapy. While these areas often involve elaboration of existing porphyrin systems aided by advances in instrumentation or synthetic methodology, several classes of novel tetrapyrroles have been developed which exhibit considerably altered properties when compared to "normal" porphyrins. Examples for this are the expanded porphyrins (see Chapter 8 by Sessler in this Handbook) porphyrins in which one or more macrocycle atoms have been exchanged for heteroatoms (see Chapter 14 by Latos-Gru2yiskt in this Handbook) and specifically =/designed nonplanar porphyrins

https://dx.doi.org/10.1002/chin.200317265

Structure and Conformation of Tetra-meso-, Octa-β-, and Dodecasubstituted 22,24-Dihydroporphyrins (Porphyrin Dications).

Senge, M. O., Kalisch, W. W., Structure and Conformation of Tetra-meso-, Octa-Β-, and Dodecasubstituted 22,24-Dihydroporphyrins (Porphyrin Dications), Èe;Z. Naturforsch. B, 1999, 54, 7, 943-959.

A comparative crystallographic analysis of the conformation of porphyrin diacids with various substituent types reveals considerable differences in the degree of nonplanarity and distortion modes. Diacids of 5,10,15,20-tetraarylporphyrins generally exhibit typical saddledistorted macrocycles with displacements of the Cb positions in the range of 0.7-1.0 Å. Adding peripheral substituents, i.e., using dodecasubstituted porphyrins for the diacid formation yields similar distortion types albeit with larger out-of-plane displacements. As a result of the combined effect of both peripheral (interaction between the Cb and Cm substituents) and core (interaction between the four inner hydrogen atoms) steric strain the maximum Cb displacements reach 1.3-1.5 Å. Quite a different situation is observed for the diacids of 2,3,7,8,12,13,17,18-octaalkylporphyrins. Here, macrocycles with pair-wise displacement of neighboring pyrrole rings and significant NH pyramidalization and those with classic saddle distortion are found. Generally, octa- Β-substituted porphyrin diacids show smaller degrees of nonplanarity; Cb displacements ranged from 0.06 to 0.72 Å. On the basis of the overall degree of conformational distortion (Δ24 = average deviation of the 24 macrocycles atoms from the mean plane), the three different types of porphyrin macrocycles studied differ considerably in their degree of conformational flexibility. For several porphyrin crystal structures with different counterions and/or solvate molecules were obtained. Taking into account results from the literature 2,3,7,8,12,13,17,18-octaethyl-22,24-dihydro-5,10,15.,20-tetraphenylporphyrin (13) shows the smallest degree of flexibility (Δ24 = 0.61-0.63 Å; four different X-ray structures), while 22,24-dihydro-5,10,15,20-tetraphenylporphyrin (1) is more flexible (ZΔ24 = 0.42-0.52 Å; four structures). The largest flexibility is observed for 2,3,7,8,12,13,18-octaethyl- 22,24-dihydroporphyrin (7) (Δ24 = 0.02-0.33 Å; four structures).

https://dx.doi.org/10.1515/znb-1999-0719

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 12. A Crystallographic Analysis of Porphyrin-Quinones and Their Precursors.

Senge, M. O., Speck, M., Wiehe, A., Dieks, H., Aguirre, S., Kurreck, H., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 12. A Crystallographic Analysis of Porphyrin-quinones and Their Precursors. Photochemistry and Photobiology, 1999, 70, 2, 206-216.

A comprehensive crystallographic analysis of 10 porphyrin quinone precursors (dimethoxybenzene derivatives), and six porphyrin quinones has been performed. The free bases and zinc(II) complexes of the porphyrin quinones are of the 5,10,15-triaryl/alkyl-20-quinone-porphyrin type and carry various bridging and quinone units. The structural and conformational parameters were determined for all compounds; the donor-acceptor separation distances range from 6.3 to 10.9 Å. Knowledge of these data is a prerequisite for a detailed interpretation of theoretical and spectroscopic studies on such systems. Despite the obvious influence of the type and geometry of the bridging unit and quinone on the spatial arrangement of the donor and acceptor components, a large variety of different packing arrangements in the crystal were observed. These include Π stacking, aggregate formation and axial ligation in the zinc(II) porphyrins. The latter often utilized the quinone (or dimethoxy) oxygen atoms for coordination to zinc(II) centers leading to porphyrin quinone dimers and even polymers.

https://dx.doi.org/10.1111/j.1751-1097.1999.tb07991.x

Reaction of β-Formylporphyrins with Organometallic Reagents - A Facile Method for Preparation of Porphyrins with Exocyclic Double Bonds.

Runge, S., Senge, M. O., Reaction of Β-formylporphyrins with organometallic reagents — A facile method for the preparation of porphyrins with exocyclic double bonds, Tetrahedron, 1999, 55, 34, 10375-10390.

5,10,15,20-Tetralkyl-2-formylporphyrins were treated with various organolithium reagents to form porphyrins with exocyclic double bonds. The reaction involved conversion with LiR to the respective alcohol. Subsequence dehydratization of the alcohols yielded olefinic systems in which the double bond formed was located in the meso substituent neighboring the Β position, i.e., the result of a 1,5-hydride shift. Depending on the organolithium reagent used various olefinic porphyrins are accessible, provided the stability of the intermediary carbenium ion is high enough. Furthermore, use of a Peterson olefination allowed the facile synthesis of 2-vinyl-5,10,15,20-tetralkylporphyrins and use of an organodilithium reagent gave convenient access to functionalized bisporphyrins. 2-Formyltetraalkylporphyrins were reacted with various organolithium reagents to form porphyrins with exocyclic double bonds. Furthermore, use of a Peterson olefination allowed the facile synthesis of 2-vinyl-5,10,15,20-tetralkylporphyrins and use of an organodilithium reagent gave access to functionalized bisporphyrins.

https://dx.doi.org/10.1016/s0040-4020(99)00579-7

Fixation of Neutral Molecules in the Binding Cavity of Nonplanar Porphyrins - A Third Dodecaphenylporphyrin Modification with NH-Solvent Hydrogen Bonding.

Senge, M. O., Fixation o f Neutral Molecules in the Binding Cavity of Nonplanar Porphyrins - A Third Dodecaphenylporphyrin Modification with NH -Solvent Hydrogen Bonding, Z. Naturforsch. B, 1999, 54, 6, 821-821.  

A third crystalline modification of dodecaphenylporphyrin is described in which the pyrrole nitrogen atoms are hydrogen-bonded to two ethanol molecules. This is the first crystallographic proof for the accessibility of nitrogen atoms in saddle-distorted free base porphyrins for hydrogen bonding. No such coordination is possible in either planar or ruffled porphyrins. Thus, the possibility exists to utilize conformationally distorted porphyrins for the binding of neutral molecules.

https://dx.doi.org/10.1515/znb-1999-0620

5,10,15,20-Tetrakis(diphenylmethyl)porphyrin - A Nonplanar Porphyrin with Intermediate Degree of Ruffling.

Runge, S., Senge, M. O., Ruhlandt-Senge, K., 5,10,15,20 Tetrakis(diphenylmethyl)porphyrin - A Nonplanar Porphyrin with Intermediate Degree of Ruffling, Z. Naturforsch. B, 1999, 54b, 662-666.

The title compound was prepared by condensation of pyrrole and diphenylacetaldehyde in 16% yield. Based on spectroscopic data, the free base porphyrin exhibits a nonplanar macrocycle in solution with a degree of distortion between that of 5,10,15,20-tetracyclohexylporphyrin and 5,10,15,20-tetra(r-butyl)porphyrin. A crystal structure determination of the cobalt(II) complex reveals a ruffled macrocycle conformation with an average out-of-plane displacement of the meso carbon atoms by 0.55 A.

https://dx.doi.org/10.1515/znb-1999-0515

Triplet Dynamics of Conformationally Distorted Porphyrins in Isotropic Liquids and Liquid Crystals. Time-Resolved Electron Paramagnetic Resonance Study.

Michaeli, S., Soffer, S., Levanon, H., Senge, M. O., Kalisch, W. W., Triplet Dynamics of Conformationally Distorted Porphyrins in Isotropic Liquids and Liquid Crystals. Time-Resolved Electron Paramagnetic Resonance Study. J. Phys. Chem. A, 1999, 103, 13, 1950-1957.  

The photoexcited tripler states of four nonplanar (distorted) porphyrins were examined by laser excitation-time-resolved EPR spectroscopy. The compounds examined were 2,3,7,8,12,13,17,18-octaethyl-5,10, 15,20-tetraphanylporphyrin (H2OETPP); 2,3-diethyl-5,10, 15,20-tetraphenylporphyrin (H2DETPP); 2,3,12, 13-tetraethyl-,lo,10,20-tetraphenylporphyrin(H(2)tTETPP)and 2,3,7,8-tetraethyl-5,10,15,20-tetraphenyporphyrin (H(2)cTETPP). Measurements were carried out at low temperatures in glassy isotropic matrixes and over a wide temperature range in a uniaxial LC (liquid crystal, E-7). The triplet states of H(2)tTETPP, H(2)cTETPP, and H2OETPP are characterized by relatively small zero-field splitting (ZFS) values, D, compared to free base porphyrin (H2TPP), For the H2OETPP the relation D similar to 3E between the ZFS parameters was observed. In the case of H2DETPP the ZFS parameter D was found to be larger relative to H2TPP. Line shape analyses indicate that the tripler spectra depend on the specific chromophore, the temperature, and the LC phase. The results in LC suggest that intermolecular triplet energy transfer occurs in all four chromophores, and in the case of H2OETPP there is evidence for the simultaneous presence of two types of triplets (different saddle conformers of H2OETPP), which are identical in their ZFS parameters. To check on the sign of D and triplet spin alignment, the photoexcited tripler states in isotropic solvents were investigated by fast EPR-magnetophotoselection through the determination of the position of the optical transition moment. These experiments allow determining the location of the optical transition moment and the triplet spin alignment.

https://dx.doi.org/10.1021/jp983772e

Synthesis of Directly meso-meso Linked Bisporphyrins Using Organolithium Reagents.

Senge, M. O., Feng, X., Synthesis of directly meso-meso linked bisporphyrins using organolithium reagents, Tetrahedron Lett., 1999, 40, 22, 4165-4168.

Reaction of easily available 5,15-disubstituted free base porphyrins with organolithium reagents under anhydrous conditions affords 5,10,15-trisubstituted porphyrin anions that, upon oxidation with DDQ (2,3-dichloro-5,6-dicyano-p-quinone), give directly linked (5,5′) bisporphyrins in good yields. This method allows the facile preparation of bisporphyrins with mixed meso substituent pattern. Treatment of 5,15-disubstituted porphyrins with RLi followed by oxidation with DDQ yields directly linked bisporphyrins.

https://dx.doi.org/10.1016/s0040-4039(99)00745-5

Reactivity of Zinc(II) 5-Oxoniaprotoporphyrin: Synthesis of the First 5-Oxonia-15-phlorin.

Clement, T. E., Gerlach, B., Senge, M. O., Smith, K. M., Reactivity of Zinc(II) 5 Oxoniaprotoporphyrin: Synthesis of the First 5-Oxonia-15-phlorin, Heterocycles, 1999, 50, 641-644.

The reactivity of zinc(II) 5-oxoniaprotoporphyrin-IX with selected carbon nucleophiles is demonstrated to be highest at the 15-C m e s o position, enabling the first synthesis of a 5-oxonia-15-phlorin which has been isolated and studied by X-Ray crystallography.

https://dx.doi.org/10.3987/COM-98-S(H)44

On the Molecular Stereochemistry of the 21,22,23-Trimethyl-5,10,15,20.

Senge, M. O., On the Molecular Stereochemistry of the 21,22,23-trimethyl-5,10,15,20-Tetraphenylporphyrin Cation, J. Porphyr. Phthalocya., 1999, 03, 03, 216-223.

The crystal structure of the triflate salt of the title compound, [Me3TPP][CF3SO3], was investigated to obtain structural information on the conformation of N-trimethylated 5,10,15,20-tetraarylporphyrins. The molecular stereochemistry of the cation is characterized by an up/down/up arrangement for the three N-methyl groups with significant pyramidalization at the nitrogen atoms. The macrocycle is severely distorted with an average deviation from planarity of 0.438ߕÅ. The distortion mode is an asymmetric saddle with deviations from the 4N plane of the Cb atoms at N-methylated pyrrole rings exceeding 1.1ߕÅ. The out-of-plane displacements of pyrrole ring IV are significantly smaller than those of the methylated pyrrole rings.

https://dx.doi.org/10.1002/(sici)1099-1409(199903)3:3<216::aid-jpp125>3.0.co;2-b

Synthesis, Reactivity, and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins.

Senge, M. O., Bischoff, I., Nelson, N. Y., Smith, K. M., Synthesis, Reactivity and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins, J. Porphyr. Phthalocya., 1999, 03, 02, 99-116.

The synthesis, reactivity and full characterization of a series of meso-tetraalkyl porphyrins and metalloporphyrins with R ࣕ n-butyl (6), 2-methyl-propyl (7), isopropyl (8), l-ethyl-propyl (10) and tert-butyl (11) groups are reported. Derivatives of the last of these show considerably bathochromically shifted absorption bands and the crystal structure of Zn(II)11(pyr) exhibits a severely ruffled macrocycle conformation. Systematic crystallographic studies of the porphyrins showed that the free base porphyrins with R ࣕ n-butyl (H26), 2-methyl-propyl (H27) and 1-ethyl-propyl (H210) are planar. A larger conformational variety was found for the metal complexes. While most Ni(II) derivatives and Pd(II)8 showed a ruffled macrocycle conformation with a degree of ruffling exceeding that of meso-unsubstituted porphyrins, both planar and non-planar forms were found for the related Cu(II) derivatives. The Zn(II) complexes of porphyrins with isopropyl or 1-ethyl-propyl exhibited conformations with variable degree of distortion. Together with comparative structures from the literature, this study provides experimental evidence that considerable conformational flexibility exists for meso-alkylporphyrins with substituents less bulky than tert-butyl groups.

https://dx.doi.org/10.1002/(sici)1099-1409(199902)3:2<99::aid-jpp109>3.0.co;2-6 

Synthesis and Characterization of Na2{Ge(C6H3-2,6-Trip2)}2 and K2{Sn(C6H3-2,6-Trip2)}2 (Trip = -C6H2-2,4,6-i-Pr3): A New Class of Multiply Bonded Main Group Compounds.

Pu, L., Senge, M. O., Olmstead, M. M., Power, P. P., Synthesis and Characterization of Na2{Ge(C6H3-2,6-Trip2)}2and K2{Sn(C6H3-2,6-Trip2)}2(Trip = -C6H2-2,4,6-i-Pr3): A New Class of Multiply Bonded Main Group Compounds, J. Am. Chem. Soc., 1998, 120, 48), 12682-12683.

It has long been recognized that multiple bonding in the heavier main group 14 elements1 differs fundamentally2 from that observed for carbon compounds. For example, the structures of Si, Ge, Sn, or Pb species corresponding to alkenes display an increasing tendency to adopt nonplanar, trans-bent structures with progressively weaker element-element bonding as the group is decended.2 About thirty structures of compounds of formula R2MMR2 (M ) Si, Ge, Sn, or Pb, R ) organo group) are known, and their spectroscopic and chemical properties have been studied in detail.1 In contrast, experimental data from the heavier group 14 species which correspond to alkynes (RMMR) are almost nonexistent.3 The singly reduced species [K(THF)6][{Sn(C6H3- 2,6-Trip2)}2] (1)4 represents the closest such approach, but its structure strongly suggests that the singly bonded isomeric form of the neutral (and as yet unisolated) distannylene {Sn(C6H3-2,6- Trip2)}2 is preferred over the triple bonded ″distannyne″ valence isomer.5 Thus, the ion, [{Sn(C6H3-2,6-Trip2)}2]-, has a Sn-Sn distance of 2.8123(9) Å and a planar, but nonlinear, C(ipso)- SnSnC(ipso) array featuring an Sn-Sn-C angle of 95.2(13)°. This suggests that there is a lone pair of electrons located at each tin which occupy orbitals high in s character with p orbitals employed in Sn-Sn and Sn-C Σ-bonding. The remaining p orbital at each tin may then overlap to form a Π orbital which in 1 is occupied by one electron. The tins can thus be considered to be connected by a two-electron Σ bond and a Π bond of order 0.5 to afford an overall, Sn-Sn bond order of 1.5 (cf. Sn-Sn single bond of 2.80 Å in gray tin).6 To further investigate the bonding in such compounds, we are engaged in a program to synthesize the related doubly reduced [RMMR]2- and neutral RMMR (M ) Sn, Ge, Sn, or Pb, R ) organo group) species. Here, the isolation and characterization of the doubly reduced compounds Na2{Ge(C6H3-2,6-Trip2)}2 (2) and K2{Sn(C6H3-2,6- Trip2)}2 (3) (Trip ) C6H2-2,4,6-i-Pr3) are described. T

https://dx.doi.org/10.1021/ja982717g

Non-planar porphyrins with mixed substituent pattern: bromination and formylation of ethyl-substituted tetraphenylporphyrins and tetraalkylporphyrins.

Senge, M. O., Gerstung, V., Ruhlandt-Senge, K., Runge, S., Lehmann, I., Non-planar porphyrins with mixed substituent pattern: bromination and formylation of ethyl-substituted tetraphenylporphyrins and tetraalkylporphyrins, J. Chem. Soc., Dalton Trans., 2998, 24, 4187-4200.

A series of 5,10,15,20-tetraphenylporphyrins (TPPs) bearing different numbers and orientations of Β-ethyl substituents have been used for studies on the functionalization of non-planar porphyrins. Attempts to monofunctionalize the diethyl-TPP via monobromination failed and resulted in the isolation of two different regioisomers. All ethyl-TPPs were easily converted into the perbrominated porphyrins bearing twelve peripheral substituents but with different numbers of Β-bromo and -ethyl groups. These porphyrins are interesting precursors for further mixing of the substituent pattern and are novel push-pull porphyrins bearing electron donating and withdrawing groups in a defined pattern directly on the ring system. They have a similar degree of overall conformational distortion, however each with considerably altered electronic effects due to the different number of bromine atoms. In order to gain access to monofunctionalized derivatives, some of the ethyl-TPPs were converted into the monoformyl derivatives. In a similar manner, a number of 5,10,15,20-tetraalkylporphyrins were formylated, albeit in lower yields than the ethyl-TPPs. Several compounds were investigated in detail by single crystal X-ray crystallography and allowed a comparison of the influence of different substituent patterns on the conformation. The structural analyses include a comparison of different crystalline modifications for some compounds. Structural data for perbrominated ethyl-TPPs present the first examples of highly non-planar, dodecasubstituted porphyrins bearing two different types of Β-substituents.

https://dx.doi.org/10.1039/a806460a

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 11. 5,10,15,20-Tetrabutylbacteriochlorin.

Senge, M. O., Runge, S., Structure and Conformation of Photosynthetic Pigments and Related Compounds. XI. 5,10,15,20-Tetrabutylbacteriochlorin, Acta Crystallogr. C, 1998,54, 12, 1917-1919.

The structure of the title compound, C36H50N4, is the first example of a tetra-meso-substituted free-base bacteriochlorin (2,3,12,13-tetrahydroporphyrin). While general structural characteristics are similar to other hydroporphyrins, the present structure presents one of the few examples of a hydroporphyrin with a planar macrocycle conformation.

https://dx.doi.org/10.1107/s0108270198008749

Wittig Reaction on Chlorin: Formation of an Unexpected Chlorin-Spirochlorin Dimer with Significant Overlap Between the &#f070; Electron System.

Zheng, G., Alderfer, J. L., Senge, M. O., Shibata, M., Dougherty, T. J., Pandey, R. K., Wittig Reaction on Chlorin:  Formation of an Unexpected Chlorin—Spirochlorin Dimer with Significant Overlap between the Π Electron System, J. Org. Chem.,1998, 63, 19, 6434-6435.  

The charge separation in photosynthetic organisms occurs in membrane proteins called reaction centers (RC). To date, two RCs, those from Rd. viridis1 and Rd. sphaeroids, 2 have been characterized structurally at 2.3-3.1 Å by X-ray diffraction. In such RCs, the primary electron donor is dimeric bacteriochlorophylls (Bchl), the so-called ″special pair″ (SP).3 A desire to understand the intricacies of natural photosynthesis has motivated many chemists and molecular biologists to synthesize and to study a wide variety of arrays of covalently linked porphyrins.4 However, only a few attempts have been made to create synthetic models of the special pair.7 Thus, our goal has been to develop a methodology for the preparation of cofacial chlorin dimers with partial overlap as models for the special pair. Officer and colleagues8 have recently shown that a variety of porphyrin dimers can be constructed by using porphyrinderived Wittig reagents. This chemistry offers a versatile approach for the preparation of a variety of porphyrin-based free base and heterometalated dimers.

https://dx.doi.org/10.1021/jo981179n

Electron Donor-Acceptor Compounds. Synthesis of 5-(1,4-Benzoquinone-2-yl)-10,15,20-trialkylporphyrins.

Runge, S., Senge, M. O., Electron Donor-Acceptor Compounds. Synthesis and Structure of 5-(1,4-Benzoquinone-2-yl)-10,15,20-trialkylporphyrins, Z. Naturforsch. B , 1998, 53, 9, 1021-1030.

A series of 5-(benzoquinone)-10,15,20-trialkylporphyrins was synthesized via cross condensation of the respective aldehydes, 2,5-dimethoxybenzaldehyde and pyrrole followed by demethylation with BBr3 and oxidation with PbO2. This method worked reasonably well for compounds bearing the benzoquinone substituent and butyl, isopropyl, 1 -methylpropyl and 2-ethylpropyl residues (2a-d). The free base porphyrin quinones were converted into the zinc(II) complexes (3a-d) all of which showed remarkable stability for porphyrin quinones. The zinc(II) complex 3c bearing isopropyl residues was investigated by X-ray crystallography and showed a supramolecular structure consisting of polymeric chains facilitated by coordination of a benzoquinone oxygen to a neighboring zinc(II) center. Attempts to synthesize a 5-(benzoquinone)-10,15,20-tris(terr-butylporphyrin) resulted in the formation of a yellow porphomethene (4), which could not be oxidized further. A crystal structure analysis of 4, the first for a free base porphomethene, shows an extremely twisted conformation with syn-orientation of the three tert-butyl groups. The results indicate that new methods will have to be developed for the synthesis of nonplanar porphyrin quinones.

https://dx.doi.org/10.1515/znb-1998-0914

Novel Structural Principles in Magnesium Thiolate Chemistry: Monomers, Trimers, and the First Magnesiate Thiolate.

Chadwick, S., Englich, U., Senge, M. O., Noll, B. C., Ruhlandt-Senge, K. Novel Structural Principles in Magnesium Thiolate Chemistry: Monomers, Trimers, and the First Magnesiate Thiolate, Organometallics, 1998, 17, 14, 3077-3086.

The synthesis and characterization of a family of magnesium thiolates [Mg(SR)2(donor)n]m (R = C6H5, C6F5, -2-NC5H4; n = 1—4; m = 1, 3) and the first magnesiate thiolate [cat]2[Mg(SC6F5)4] are described. Mg(SC6F5)2(py)3, 1 (py = pyridine), Mg(SPh)2(py)4, 2, the trimer Mg3(Μ2-SPh)6(py)6, 3, the intramolecularly stabilized monomer Mg(S-2-NC5H4)2(py)2, 4, and the ″ate″ complex [2,6-lutidineH]2[Mg(SC6F5)4], 5, were synthesized by treating (C4H9)2Mg with HSC6F5, HSC6H5, or HS-2-NC5H4 under addition of pyridine or 2,6-dimethylpyridine. The target molecules were characterized by IR and, depending on solubility, 1H NMR and 13C NMR spectroscopy, melting point, and single-crystal X-ray crystallography. It is clearly shown that the structural chemistry, and therefore the physical properties of the magnesium thiolates, can be influenced by ligand and donor choice, as exemplified by the significant structural variations observed. Use of HSC6F5 and pyridine resulted in the formation of five-coordinate Mg(SC6F5)2(py)3·C6H5CH3, 1a, and the solvent-free Mg(SC6F5)2(py)3, 1b; while utilization of HSC6H5 and pyridine resulted in the formation of the six-coordinate species Mg(SPh)2(py)4, 2, and Mg3(Μ2-SPh)6(py)6, 3. Interestingly, compounds 2 and 3 are isolated from almost identical reaction mixtures and are related by an equilibrium:ߙ addition of large amounts of pyridine results in the formation of 2 while reduced amounts of donor allow the isolation of the novel trimer 3. The intramolecularly stabilized, distorted-octahedral complex Mg(S-2-NC5H4)2(py)2, 4, becomes available if 2-mercaptopyridine is used in conjunction with pyridine. A rare example of an anionic alkaline-earth derivative, the tetrahedrally coordinate [2,6-lutidineH]2[Mg(SC6F5)4], 5, is accessible by treating (C4H9)2Mg with 4 equiv of HSC6F5 and adding 2,6-lutidine.

https://dx.doi.org/10.1021/om980012h

Facile meso Functionalization of Porphyrins by Nucleophilic Substitution with Organolithium Reagents.

Kalisch, W. W., Senge, M. O., Facile meso Functionalization of Porphyrins by Nucleophilic Substitution with Organolithium Reagents, Angew. Chem. Int. Ed., 1998, 37, 8, 1107—1109.

The ruffle of the porphyrin increases with the number of meso substituents. (Octaethylporphyrin)nickel(II) undergoes nucleophilic substitution reactions upon treatment with alkylating reagents such as butyllithium, hydrolysis with water, and oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone [DDQ; Eq. (a)]. Alkylation can be achieved at all four meso positions, and access is provided to new nonplanar porphyrins and asymmetrically substituted systems.

https://dx.doi.org/10.1002/(sici)1521-3773(19980504)37:8<1107::aid-anie1107>3.0.co;2-z

Porphyrins Like Boron After All

Senge, M. O., Porphyrins Like Boron After All, Angew. Chem. Int. Ed., 1998, 37, 8, 1071-1072.

The central core and the macrocycle skeleton of porphyrins both offer room for boron, and a gap in the chemistry of nonmetal-containing porphyrins has now been filled. In one case a four-membered B2O2 ring coordinates to a porphyrin cavity that has been distorted to a rectangle (A), and in the other case four boron atoms are located in the meso positions of a tetrathiaporphyrinogen (B).

https://dx.doi.org/10.1002/(sici)1521-3773(19980504)37:8<1071::aid-anie1071>3.0.co;2-q

Conformationally Distorted Chlorins via Diimide Reduction of Nonplanar Porphyrins.

Senge, M. O., Kalisch, W. W., Runge, S., Conformationally distorted chlorins via diimide reduction of nonplanar porphyrins, Tetrahedron, 1998, 54, 15, 3781-3798.

Tetraphenylporphyrins with varying degree of Β-ethyl substitution were reduced with diimide to the respective chlorins. Increasing nonplanarity of the parent porphyrins led to successively more instable chlorins and the most nonplanar chlorins that could be isolated, were based on a tetra-Β-ethyl-tetra-meso-phenyl-macrocycle. Depending on the substituent pattern different isomers were formed and crystal structure analysis showed the chlorins to possess varying degrees of conformational distortion depending on the degree of peripheral substitution and the localization of the pyrrolenine ring. Highly substituted free base chlorins exhibited a larger degree of ring distortion than their parent porphyrins. Nonplanar chlorins with graded degree of conformational distortion were prepared via reduction of Β-ethyl substituted tetra-phenylporphyrins.

https://dx.doi.org/10.1016/s0040-4020(98)00106-9

Synthesis and Spectroscopic Properties of Novel Benzochlorins Derived from Chlorophyll-a.

Mettath, S., Shibata, M., Alderfer, J. L., Senge, M. O., Smith, K. M., Rein, R., Dougherty, T.J., Pandey, R. K., Synthesis and Spectroscopic Properties of Novel Benzochlorins Derived from Chlorophyll a, J. Org. Chem., 1998, 63, 5, 1646-1656.

Methylpheophorbide-a (a chlorophyll a analog) was converted into methyl 131-deoxypyropheophorbide-a2 in excellent yield. The Ni(II) complex of 2 on hydrogenation and subsequent Vilsmeier reaction with phosphorus oxychloride and 3-(N,N-dimethylamino)acrolein produced Ni(II) methyl 20-(2-formylvinyl)-131-deoxypyropheophorbide-a4. In contrast to other synthetic and naturally occurring isobacteriochlorins, the isobacteriochlorin obtained by acid-catalyzed cyclization of 4 was found to be unstable and oxidized to the corresponding benzochlorin. The free base benzochlorin 7, obtained by demetalation, up on DDQ/methanol treatment produced a mixture of 132-oxo- and 131-methoxy-132-oxobenzochlorins 8, 9. Surprisingly, under similar reaction conditions, an ethanolic solution of DDQ afforded 131,132-dioxobenzochlorin 13 as a major product. Vilsmeier reaction (POCl3/DMF) of Ni(II) benzochlorin 6 gave unexpected 5-formyl-132-oxobenzochlorin 15. Zn(II) complexes of the newly synthesized benzochlorins showed long wavelength absorptions in the range of 750—753 nm. Thus, compared to the respective free base analogues bathochromic shifts of 40—42 nm were observed. Despite extensive studies in benzochlorins, these are the first examples which exhibit such remarkable long wavelength absorptions in their electronic absorption spectra. The structures of novel benzochlorins were confirmed by extensive NMR [2D NMR (ROESY), 13C NMR] and X-ray crystallographic studies. On the basis of the crystal structure of oxobenzochlorin 8, the chemical reactivity of other benzochlorin analogues were examined by semiempirical molecular orbital theory. Our results are in agreement with the previous qualitative electron sextet hypothesis proposed for chlorin systems by Woodward. The fluorescence quantum yields and the singlet oxygen yields of the free base and Zn(II) benzochlorins were measured relative to tetraphenylporphyrin (TPP) in benzene.

https://dx.doi.org/10.1021/jo971968p

Synthesis and Structural Characterization of Cofacial Bisoctaethylchlorins as Models for the Special Pair.

Kalisch, W. W., Senge, M. O., Ruhlandt-Senge, K., Synthesis and Crystal Structures of Cofacial Bisoctaethylchlorins as Structural Models for the Special Pair, Photochem. Photobiol., 1998, 67, 3, 312—323.

Covalently linked bistetrapyrrole systems can be used to mimic structurally the arrangement of the two special pair bacteriochlorophylls in the bacterial photosynthetic reaction center. Such models require a cofacial arrangement of the two tetrapyrrole units with some overlap of the It systems and intramolecular stabilization by aggregation of the two macrocycles. Using the McMurry re-action for the coupling of metallo formyloctaethylchlorins, covalently linked cofacial bischlorins were prepared and characterized by spectroscopy and single crystal X-ray crystallography. Coupling of NI(II)5-formyloctaethylchlorin yielded a (Z)-ethene-bridged bischlorin with cofacial orientation of the subunits stabilized by intramolecular Π-Π interactions that structurally resembles the situation found for the special pair in bacterial reaction centers. In addition, two different atropisomers of the respective (E)-ethene-bridged bischlorin were formed. Use of Cu(II)5-formyloctaethylchlorin yielded similar products, however a crystal structure showed a (Z)-ethene-bridged bischlorin without intramolecular stabilization via aggregation effects. The bischlorins are easily oxidized to mixed chlorin-porphyrin species.

https://dx.doi.org/10.1111/j.1751-1097.1998.tb05204.x

Axial Ligand Effects in Sterically Strained Porphyrins. A Crystallographic Study of Five- and Six-Coordinated Metal Complexes of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin.

Senge, M. O., Axial Ligand Effects in Sterically Strained Porphyrins: A Crystallographic Study of Five- and Six-coordinated Metal Complexes of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin, J. Porphyr. Phthalocya., 1998, 2, 107-121.

Porphyrins with steric hindrance at the periphery are known to exhibit severely non-planar macrocycle conformations. Among other dodecasubstituted porphyrins, the title compound has been studied widely and shows a typical saddle-distorted macrocycle. The specific conformation of the porphyrin leads to the formation of distinct cavities on both sides of the macrocycle. Compared to planar porphyrins this should increase steric interactions between the macrocycle and axial ligands in five- and six-coordinated metal derivatives. In order to study the influence of different axial ligands on the conformation (or vice versa) a variety of five- and six-coordinated metal derivatives of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetranitroporphyrin (oetnp) were prepared and their conformation investigated by X-ray crystallography. Structuraldata for ZnII oetnp (L) where L is imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 3,5-lutidine clearly indicated that a mutual influence exists between axial ligands and non-planar porphyrins. An asymmetric macrocycle distortion and axial ligand orientation was found in the sterically hindered 2- and4-methylimidazole derivatives. The presence of four electron-withdrawing nitro-groups led to the formationof the novel polymeric porphyrins (ZnIIoetnp)n and (CoIIoetnp)n where polymer formation was achieved viathe utilization of nitro oxygen atoms as axial ligands to the metal centre of neighbouring porphyrins. The structure of the six-coordinated NiIIoetnp(pyr)2 (where pyr is pyridine) yielded first structural data on neutral, non-planar, high-spin Ni(II) porphyrins. A comparison with the respective low-spin NiIIoetnp clearly showed that a change to the high-spin form leads to a less non-planar macrocycle conformation further proving thatspin state changes can have a profound effect on the conformation in distorted porphyrins.

https://dx.doi.org/10.1002/%28SICI%291099-1409%28199803/04%292%3A2<107%3A%3AAID-JPP57>3.0.CO%3B2-T

Synthesis and Structural Chemistry of Nonplanar Tetraphenylporphyrins and Their Metal Complexes with Graded Degree of β-Ethyl Substitution.

Senge, M. O., Kalisch, W. W., Synthesis and Structural Characterization of Nonplanar Tetraphenylporphyrins and Their Metal Complexes with Graded Degrees of Β-Ethyl Substitution, Inorg. Chem., 1997, 36, 26, 6103-6116.

Different porphyrin conformations are believed to play a role in controlling the cofactor properties in natural tetrapyrrole—protein complexes. In order to study the correlation between macrocycle nonplanarity and physicochemical properties in detail, a series of six porphyrins with graded degrees of macrocycle distortion were synthesized via mixed condensation of pyrrole, diethylpyrrole, and benzaldehyde. The formal introduction of successively more Β-ethyl groups into the tetraphenylporphyrin parent macrocycle gave access to diethyltetraphenylporphyrin (H2DETPP), two regioisomers of tetraethyltetraphenylporphyrin (H2tTETPP, H2cTETPP), and hexaethyltetraphenylporphyrin (H2HETPP). These conformationally designed compounds bridge the gap between the well-known tetraphenylporphyrin (H2TPP) and the very nonplanar octaethyltetraphenylporphyrin (H2OETPP), which are also formed during the reaction. Crystallographic studies showed that the macrocycle distortion in the solid state increases gradually in the order TPP < DETPP < tTETPP < cTETPP < HETPP < OETPP, i.e. with increasing degree of Β-ethyl substitution and the number and localization of potential Β-ethyl meso-phenyl interactions. This correlates well with increasing bathochromic shifts of the absorption bands in solution. Depending on the substituent pattern, different saddle-shaped macrocycle conformations were observed. While the conformation of tTETPP was symmetric, DETPP, cTETPP, and HETPP showed asymmetric distortion modes with individual Β-pyrrole displacements reaching those described for dodecasubstituted porphyrins. Overall, higher displacements from planarity were found close to Β-ethyl—meso-phenyl groups whereas smaller displacements were observed in parts of the molecules bearing Β-hydrogen atoms. Nevertheless, a certain amount of redistribution of steric strain occurs as evidenced by significant displacements for pyrrole carbon atoms with Β-hydrogens. Synthesis and structural investigation of the respective metal complexes with M = Cu(II), Ni(II), and Zn(II) showed similar correlations between Β-ethyl substitution, bathochromic shift of absorption bands and nonplanarity as described for the free bases. The only exception was found for NiIItTETPP, which exhibited a highly nonplanar ruffled conformation. Additionally, the metal complexes allowed a study of the conformational effects of different metals at each level of macrocycle distortion. As observed for symmetric, nonplanar porphyrins larger metals led to a decrease in conformational distortion with associated changes in bond lengths and bond angles.

https://dx.doi.org/10.1021/ic970765g

Cyclohexylene-Bridged Porphyrin-Quinones With Variable Acceptor Strength as Biomimetic Models for Photosynthesis: Evidence for Twist-Boat-Conformation.

Dieks, H., Senge, M. O., Kirste, B., Kurreck, H., Cyclohexylene-Bridged Porphyrin Quinones with Variable Acceptor Strength as Biomimetic Models for Photosynthesis: Evidence for Twist-Boat Conformation, J. Org. Chem., 1997, 62, 25, 8666-8680.

Rigidly and covalently linked porphyrin quinones are well-suited as biomimetic model compounds for studying the photoinduced electron transfer (PET) reaction occurring in primary processes of photosynthesis. In this context, the synthesis of new porphyrin quinones with a cis- or trans-1,4- disubstituted cyclohexylene bridge linking the electron donor and the electron acceptor is reported. To study the dependence of the PET rate of the difference of the free enthalpy of the PET reaction, four quinones with different structures and therefore redox potentials were used as electron acceptor components. As a whole, two series of each four new cis- and trans-1,4-cyclohexylene-bridged porphyrin quinones with variable acceptor strength were synthesized. The most important synthetic steps comprised the free radical addition of the ester functionalized cyclohexylene bridge to the quinone, reduction of the ester to the alcohol group with lithium borohydride or DIBALH, oxidation of the alcohol to the corresponding aldehyde with PCC or TEMPO (2,2,6,6 tetramethylpiperidine1-oxyl)/NaOCl, and condensation of these aldehydes with pyrrole and 4-methylbenzaldehyde under equilibrium conditions. Analysis of the 1H NMR spectra unambiguously indicated the chair conformation for the cyclohexane ring of all porphyrin precursors and trans-cyclohexane-bridged porphyrin quinones, whereas the cis-cyclohexane-bridged porphyrin quinones had the cyclohexane ring in the unusual twist-boat conformation. This was additionally confirmed by an X-ray crystal structure of one of the cis-porphyrin quinones and the corresponding trans-porphyrin quinone. NOE experiments gave information about the spatial arrangement of the diastereomeric target compounds in solution.

https://dx.doi.org/10.1021/jo970752k

Novel oxidation reactions of sterically demanding 3,6-di-tert-butylporphyrin-o-quinones to muconic anhydride derivatives

Speck, M., Senge, M. O., Schäfer, A., Kurreck, H., Novel oxidation reactions of sterically demanding 3,6-di-tert-butylporphyrin-o-quinones to muconic anhydride derivatives, Bioorg. Med. Chem. Lett., 1997, 7, 20, 2589-2592.

Porphyrin quinones with sterically demanding 3,6-di-tert-butyl-o-quinones were synthesized for electron transfer studies. In the presence of atmospheric oxygen the covalently free base porphyrin-o-quinones are oxidized to muconic acid anhydride and 3,6-dicarbonyl-derivatives. In contrast to the well established chemistry of catecholase models based on 3,5-substituted quinones this is the first example for oxidative ring expansion of 3,6-disubstituted o-quinones. Covalently linked porphyrin-quinones with 3,6-di-tert-butyl groups undergo oxidative ring expansion to muconic acid derivatives.

https://dx.doi.org/10.1016/s0960-894x(97)10027-0

One-step Synthesis of Functionalized Triptycene-Quinones as Acceptors for Electron-transfer Compounds.

Wiehe, A., Senge, M. O., Kurreck, H., One-Step Synthesis of Functionalized Triptycene-quinones as Acceptors for Electron-Transfer Compounds, Liebigs Ann, 1997, 9, 1951-1963.

The synthesis of appropriate porphyrin-quinone electrontransfer complexes as model compounds for photosynthesis requires access to functionalized triptycene quinone aldehydes with different redox potentials. A synthetic strategy involving a classical Diels- Alder reaction, tautomerization and oxidation was only of limited utility for preparing the desired compounds. Thus, an alternative approach was required and for this purpose a strategy involving the reaction of excess quinone with appropriate anthracene derivatives in acetic acid has been developed. This method affords the target compounds in a single synthetic step in good yields and with high purity. The aldehyde functionality required for the subsequent porphyrin synthesis can be incorporated into either the anthracene or the quinone starting component. Fifteen different triptycene quinones have been synthesized, eight of which have been studied in detail by single crystal X-ray crystallography to provide insight into their structural chemistry and solid-state aggregation properties. Additionally, the synthesis of two porphyrin-quinone target compounds is described.

https://dx.doi.org/10.1002/jlac.199719970922

Functionalization of Corroles: Formylcorroles.

Paolesse, R., Jaquinod, L., Senge, M. O., Smith, K. M., Functionalization of Corroles: Formylcorroles, J. Org. Chem., 1997, 62, 18, 6193-6198.

Porphyrins and metalloporphyrins can be readily functionalized at the meso-(5,10,15,20)-positions by using a variety of reagents, the Vilsmeier formylation reaction being universally regarded as the prototypical example. On the other hand, the literature shows that corroles and metallocorroles are unusually resistant to most functionalization procedures which are common to porphyrins. The first example of peripheral functionalization of the corrole ring is now reported. Octamethylcorrole 1 readily reacts with the Vilsmeier reagent (POCl3/DMF), but the product is the 10-dimethylaminomethene derivative 2, and not the expected meso formyl derivatives 3 or 4, as confirmed by a single crystal X-ray crystallographic study. Corrole 5, where the 10-meso-position is substituted, affords the similar product 6. When the reaction is extended to corrole 7 two different products, 8 and 9, are obtained wherein the substitution is performed at both 5- and 10-mesopositions. Unlike the case of porphyrins, no reaction occurs at the â-unsubstituted pyrrolic positions. Coordination of cobalt to the dimethylaminomethenylcorroles 2 and 5 causes both metalation and tautomerization/hydrolysis to afford the originally targeted meso-formylcorrolato complexes in almost quantitative yields. Attempts to formylate cobalt complex 14 using TFA/trimethylorthoformate affords the corresponding â-formyl complexes 15 and 16, the ratio of which depends on the reaction time. meso-Formylcorroles are also obtained by way of a new direct synthesis, described herein, using a prefunctionalized a,c-biladiene 22

https://dx.doi.org/10.1021/jo9706739

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 10. Comparison of a Phytochlorin and Phytoporphyrin Derived from Chlorophyll a.

Senge, M. O., Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 10. Comparison of a Phytochlorin and Phytoporphyrin Derived from Chlorophyll a, Acta Crystallogr. C, 1997, 53, 1314-1318.

The crystal and molecular structures of 17-decarboxyethyl- 131-deoxo - 17 propylphytochlorin, C33H4oN4, (1), and phytoporphyrin methyl ester, C34H36N403, (2), are compared. Compound (1) shows structural parameters similar to those of other naturally occurring phytochlofins. Owing to the absence of any heteroatom functionalities at the periphery, no close contacts are observed in the packing of (1), in contrast to those normally found in other chlorophyll derivatives. Compound (2) presents the first structure of a free-base pheoporphyrin and forms chains stabilized by C--H.-.~ and rr-rr interactions. In contrast to the structure of (1) and other chlorins, the two pyrrole H atoms in (2) are located at rings B and D.

https://dx.doi.org/doi.org/10.1111/j.1751-1097.1991.tb02099.x

Bis[(anhydro-meso-rhodochlorinato-XV methyl ester)zinc(H)]

Senge, M. O., Smith, K. M., Bis[(anhydro-meso-rhodochlorinato-XV methyl ester)zinc(II)], Acta Crystallogr. C, 1997, 53, 8, 1022-1024.

The title compound, bis[(methyl 8,13-diethyl-2,21,22,23-tetrahydro-3,7,12,17-tetramethyl-23 -oxo-3H-benzo [at] -porphyrin- 18- carboxylato- ~;4M) zinc (II) ], [Zn(C33 H34- N403)]2, has similar structural characteristics to the naturally occurring factor F430 and forms dimers that are held together by axial interactions between the zinc(II) center and the cyclohexanone carbonyl O atom of a neighboring macrocycle [Zn--O3 2.204 (3) ,A]. These dimers form infinite stacks in the crystal stabilized by 7r-Tr interactions between the aromatic ring systems

https://dx.doi.org/10.1107/s0108270197002977

N-Methyl Derivatives of Highly Substituted Porphyrins - The Combined Influence of both Core and Peripheral Substitution on the Porphyrin Conformation

Senge, M. O., Kalisch, W. W., Runge, S., N-Methyl Derivatives of Highly Substituted Porphyrins — the Combined Influence of Both Core and Peripheral Substitution on the Porphyrin Conformation, Liebigs Ann., 1997, 7, 1345-1352.

N-Methylation of the peripherally highly substituted octaethyltetraphenylporphyrin (1) with either methyl iodide or methyl triflate gave the respective mono-, di-, tri- and tetraN methylated derivatives. Use of methyl triflate under carfully controlled conditions often gave the N-methylporphyrins in quantitative yield. The N-methylporphyrins possess both core and peripheral steric strain and are good candidates for the study of the combined conformational effect of such substituent patterns. Introduction of successively more N-methyl groups leads to a stepwise increase in the bathochromic shift of the bands by about 10-15 nm for each substitution. Crystal structure determinations of 11 and 12 showed that these molecules are indeed severely distorted and they exhibit degrees of nonplanarity which significantly exceed those observed for nonmethylated, dodecasubstituted nonplanar porphyrins and for 22,24-dihydroporphyrin dications. After methylation of meso-tetraalkylporphyrins 4-7 with methyl triflate only the respective N-methylated porphyrins 14-17 could be recovered. Use of the extremely ruffled porphyrin 8 led to formation of a 5,21,22,23,24-pentamethylated porphyrin cation with phlorin structure. Additionally, structural analysis of a cis-21,22-dimethyloctaethylporphyrin showed the first example of a porphyrin cation 20 with almost complete localization of the conformational distortion in the porphyrin half bearing the two N-methyl groups.

https://dx.doi.org/10.1002/jlac.199719970710

Metal-Catalyzed Oxidative Cyclizations of a,c-Biladiene Salts Bearing 1- and/or 19-Arylmethyl Substituents: Macrocyclic Products and Their Chemistry.

Lin, J. J., Gerzevske, K. R., Liddell, P. A., Senge, M. O., Olmstead, M. M., Khoury, R. G., Weeth, B. E.; Tsao, S. A., Smith, K. M., Metal-Catalyzed Oxidative Cyclizations of a,c-Biladiene Salts Bearing 1- and/or 19-Arylmethyl Substituents: Macrocyclic Products and Their Chemistry, J. Org. Chem., 1997, 62, 13, 4266-4276.

Several 1-mono- and 1,19-bis(p-arylmethyl)-a,c-biladiene salts were prepared and subjected to either copper(II)- or chromium(III)-assisted oxidative cyclization to yield numerous products in which the 1- or 19- substituent is adapted, eliminated, or rearranged to other points on the tetrapyrrole. For example, cyclization using copper(II) acetate of 19 ((ethoxycarbonyl)methyl)-2,3,7,8,12,13,17,- 18-octamethyl-19-(p-tolylmethyl)-a,c-biladiene dihydrobromide (25) yielded the copper(II) 20- ((ethoxycarbonyl)methyl)-1-(p-tolylmethyl)-2,3,7,8,12,13,17,18-octamethyl-1,20-dihydroporphyrin (42), copper(II) 20-(ethoxycarbonyl)-3-methylidene-2,3,7,8,12,13,17,18-octamethyl-2-(p-tolylmethyl)- chlorin (44), copper(II) 20-(ethoxycarbonyl)-2-methylidene-2,3,7,8,12,13,17,18-octamethyl-3-(p-tolylmethyl)chlorin (45), and three porphyrins: copper(II) 20 (ethoxycarbonyl)-2,3,7,8,12,13,17,18- octamethylporphyrin (3), copper(II) 2,3,7,8,12,13,17,18-octamethyl-20-p-tolylporphyrin (50), and copper(II) 20-(ethoxycarbonyl)-2,3,7,8,12,13,17,18-octamethyl-5-(p-tolylmethyl)porphyrin (47). Formation of porphyrin 47 and the intermediate chlorins 44 and 45 suggests the stepwise migration of the arylmethyl group from the 1-position in compound 42. The isolation of products from cyclization reactions of various 1,19-arylmethyl-substituted a,c-biladiene salts provides further insight into the mechanisms of metal-assisted oxidative cyclization of a,c-biladiene salts to give cyclic tetrapyrroles. Macrocyclizations of a,c-biladienes such as 25 using chromium(III) afford good yields of the metal-free 1-substituted compounds such as 43.

https://dx.doi.org/10.1021/jo9619138 

Tetracoordinated Manganese(III) alkylcorrolates. Spectroscopic Studies and the Crystal and Molecular Structure of (7,13-Dimethyl-2,3,8,12,17,18-hexaethylcorrolato)manganese(III).

Licoccia, S., Morgante, E., Paolesse, R., Polizio, F., Senge, M. O., Tondello, E., Boschi, T., Tetracoordinated Manganese(III) Alkylcorrolates. Spectroscopic Studies and the Crystal and Molecular Structure of (7,13-Dimethyl-2,3,8,12,17,18-hexaethylcorrolato)manganese(III), Inorg. Chem., 1997, 36, 8, 1564-1570.

(2,3,7,8,12,13,17,18-Octamethylcorrolato)manganese(III), [Mn(OMC)], has been characterized by several physicalmeasurements. In the presence of nitrogenous bases the complex exists as a valence tautomer [MnII(OMC·+)] as demonstrated by 1H NMR and EPR. Complete resonance assignment in the NMR spectrum has been achieved by systematic substitution of the peripheral substituents. The crystal structure of the first example of a tetracoordinated tetrapyrrolic macrocycle Mn(III) complex, (7,13-dimethyl-2,3,8,12,17,18 hexamethylcorrolato)- manganese(III), [Mn-7,13-Me2-HEC)], is also reported. Crystal data with Cu KR (Λ ) 1.541 78 Å) at 293 K are as follows: C33H39MnN4, a ) 4.671(2) Å, b ) 28.31(2) Å, c ) 20.882(6) Å, â ) 94.60(3)°, V ) 2753(2) Å3, Z ) 4, monoclinic, space group P21/n, 4088 data, R1 ) 0.0563 for 4088 observed reflections with I > 2Σ(I). The analysis reveals a high degree of planarity of the macrocycle and the existence of strong overlap between the Π systems with the formation of an infinite stack of molecules.

https://dx.doi.org/10.1021/ic960334i

Comparative Analysis of the Conformations of Symmetrically and Asymmetrically Deca- and Undeca-substituted Porphyrins Bearing Meso-Alkyl or -Aryl Groups.

Senge, M. O., Medforth, C. J., Forsyth, T. P., Lee, D. A., Olmstead, M. M., Jentzen, W., Pandey, R. K., Shelnutt, J. A., Smith, K. M., Comparative Analysis of the Conformations of Symmetrically and Asymmetrically Deca- and Undeca-substituted Porphyrins Bearing Meso-Alkyl or -Aryl Groups, Inorg. Chem., 1997, 36, 6, 1149-1163.

Conformational analysis of highly substituted porphyrins has potential implications for modeling the behavior of macrocycles in tetrapyrrole-containing protein complexes and during catalytic reactions. In order to study the influence of different substituent patterns on the conformation of the porphyrin macrocycle, a series of metal free and nickel(II) decasubstituted porphyrins bearing aryl or ethyl groups at opposite meso positions and alkyl groups at the pyrrole positions have been synthesized and characterized by X-ray crystallography. Crystal structures of the free-base porphyrins with 5,15-diaryl substituents showed negligible out-of-plane distortion but a large amount of in-plane distortion along the 5,15-axis accompanied by large bond angle changes similar to those previously seen for related porphyrins with 5,15-dialkyl substituents. Nickel(II) complexes of the 5,15-diaryl-substituted porphyrins show planar or modestly nonplanar conformations, suggesting that these complexes are not intrinsically nonplanar, whereas a complex with 5,15-diethyl substituents has a very ruffled conformation similar to those observed for related complexes with other metals. The nickel(II) complexes are also elongated along the 5,15-axis in a qualitatively similar but less dramatic fashion than are the free-base porphyrins. Spectrosopic studies (1H NMR, optical, and resonance Raman spectroscopy) suggest that conformations similar to those determined by X-ray crystallography are present in solution for the 5,15-dialkyl- and 5,15-diaryl-substituted porphyrins. Several asymmetric nickel(II) and metal-free deca- and undecasubstituted porphyrins containing both aryl and alkyl meso-substituents were also investigated. Metal-free 5,15-disubstituted porphyrins with one aryl and one alkyl group showed considerably elongated porphyrin cores, whereas nickel(II) complexes of porphyrins with 5,10- or 5,10,15-substitution patterns showed very nonplanar structures consisting mainly of ruffle and saddle type distortions.

https://dx.doi.org/10.1021/ic961156w

Pinacol-Pinacolone Rearrangements in vic-Dihydroxychlorins and Bacteriochlorins: Effect of Substituents at the Peripheral Positions

Pandey, R. K., Isaac, M., McDonald, I., Medforth, C. J., Senge, M. O., Dougherty, T. J. and Smith, K. M., Pinacol-Pinacolone Rearrangements in vic-Dihydroxychlorins and Bacteriochlorins: Effect of Substituents at the Peripheral Positions, J. Org. Chem. 1997, 62, 1463-1472.

pon reaction with osmium tetraoxide a series of porphyrins and chlorins were converted into the corresponding vic-dihydroxychlorins and bacteriochlorins. The presence of an electron-withdrawing substituent at a peripheral position on the porphyrins or chlorins deactivated that particular pyrrole unit toward oxidation, and also directed the oxidation regioselectively to the pyrrole ring opposite to the one bearing the electronegative group. The vic-dihydroxychlorins and bacteriochlorins were converted into the corresponding oxochlorins and dioxobacteriochlorins under pinacol—pinacolone reaction conditions. The migratory behavior of the various substituents were found to be quite complex, since distant conjugated peripheral substituents were able to affect the stability of the carbocation intermediates during the process; the ability to rearrange was affected not only by the intrinsic nature of the migratory group but also by steric and electronic factors operative elsewhere on the porphyrin and chlorin macrocycles. Preferential migration of the propionic ester over the methyl substituent in dioxobacteriochlorins obtained from 2,3,12,13-tetrahydroxycoproporphyrin II tetramethyl ester (IUPAC nomenclature) under pinacol—pinacolone conditions was confirmed by a single crystal X-ray study.

https://dx.doi.org/10.1021/jo960720h

Syntheses and Some Chemistry of 1,2- and 1,1-Bis(2-pyrrolyl)ethenes

Xie, H., Lee, D. A., Wallace, D. M., Senge, M. O. and Smith, K. M., Syntheses and Some Chemistry of 1,2- and 1,1-Bis(2-pyrrolyl)ethenes, J. Org. Chem., 1996, 61, 8508-8517.

trans-1,2-Bis(2-pyrrolyl)ethenes (e.g. 18—20) are prepared by McMurry-type reductive coupling of the corresponding 2-formylpyrroles. The isomeric 1,1-bis(2-pyrrolyl)ethenes (e.g. 24) are prepared as a minor byproduct in the reaction of 2-unsubstituted pyrroles (e.g. 22) with acetic anhydride under Friedel—Crafts conditions; the major product, as expected is the 2-acetylpyrrole 23. However, 5-(chloromethyl)dipyrromethanes (e.g. 35) can be obtained in high yield by reaction of 2-unsubstituted pyrroles 22 with chloroacetaldehyde diethyl acetal. Base-catalyzed elimination of HCl from 35 affords the 1,1-bis(2-pyrrolyl)ethene 24 along with the trans- and cis-1,2-bis(2-pyrrolyl)ethenes 18 and 36, respectively.

https://dx.doi.org/10.1021/jo961582z

Synthesis, Solution, Molecular and Crystal Structure of Bis[5-(Coproporphyrinato I tetraethylester)nickel(II)]1,2-ethane.

Senge, M. O., Ponomarev, G. V., Forsyth, T. P. and Smith, K. M., Synthesis, Solution, Molecular and Crystal Structure of Bis[5-(Coproporphyrinato I tetraethylester)nickel(II)]1,2-ethane, Z. Naturforsch., 1996, 51b, 1644-1648.

Vilsmeier formylation of the oporphyrin-I tetraethyl ester Ni-complex (III) followed by reduction of the intermediary imine salt (IV) with NaBH4 gave the o-dimethylaminomethyl-coproporphyrin-I Ni-complex (V). Heating the latter in methyl iodide gave 65% of the ethane- bis-porphyrin (I), which has been characterized by NMR-spectroscopy and a molecular and crystal structure investigation. The crystal structure shows an extended structure of the bisporphyrin with a parallel arrangement of the porphyrin subunits.

https://dx.doi.org/10.1515/znb-1996-1119

Selbstorganisation kovalent verbrückter, supramolekularer Verbindungen mit definierter Struktur: die bemerkenswerte Redoxreaktivität 15-meso-substituierter 5-Oxoporphyrine.

Khoury, R. G., Jaquinod, L., Nurco, D. J., Pandey, R. K., Senge, M. O. and Smith, K. M., Selbstorganisation kovalent verbrückter, supramolekularer Verbindungen mit definierter Struktur: die bemerkenswerte Redoxreaktivität 15-meso-substituierter 5-Oxoporphyrine., Angew. Chem., 1996, 108, 2657-2660.

Durch Oxidation an der 10-Position können die Titelverbindungen dimerisiert werden. Aus einem 15,15′-p-Phenylen-verbrückten Bis(oxophlorin) wurde so das robuste, stereochemisch einzigartig verknüpfte Tetrakis(isooxophlorin) 1 erhalten. Im Kristall hat 1 eine helikale Struktur, wobei n-Hexanmoleküle die Helixfurchen ausfüllen.

https://dx.doi.org/(empty)

Self-Assembling Covalently-Linked Supramolecular Arrays of Defined Structure - The Remarkable Redox Reactivity of meso-Substituted 5-Oxyporphyrins

Khoury, R. G., Jaquinod, L., Nurco, D. J., Pandey, R. K., Senge, M. O. and Smith, K. M., Self-Assembling Covalently-Linked Supramolecular Arrays of Defined Structure - The Remarkable Redox Reactivity of meso-Substituted 5-Oxyporphyrins, Angew. Chem. Int. Ed., 1996, 35, 2496-2499.

Oxidation at position 10 converts the title compounds into dimers. In an extension of this reaction a 15,15′-p-phenylene-linked bis(oxophlorin) produces the robust supramolecular array tetrakis(isooxophlorin) 1. In the crystal 1 has an overall helical structure in which the groove is filled by molecules of n-hexane.

https://dx.doi.org/10.1002/anie.199624961

Syntheses, characterization, and structural chemistry of biladien-ac-10-one and -bc-5-one metal complexes with 4N or (3N + O) co-ordination

Khoury, R. G., Senge, M. O., Colchester, J. E. and Smith, K. M., Syntheses, characterization, and structural chemistry of biladien-ac-10-one and -bc-5-one metal complexes with 4N or (3N + O) co-ordination, J. Chem. Soc., Dalton Trans., 1996, 3937-3950.

Transition-metal(II) complexes have been formed between Cu, Co, Pd, Hg, Cd, Zn and Ni and biladien-bc-5-ones or -ac-10-ones. All show spectroscopic and analytical data in accordance with the formation of 1 : 1 complexes. Reaction of 5- and 10-oxobiladienes with CuII, CoII, PdII, ZnII, CdII and HgII always gave complexes in which the metal is co-ordinated to the four pyrrole nitrogens (4N co-ordination) and led to a cyclic, helical conformation of the tetrapyrrole ligand. Reaction of biladien-ac-10-ones with NiII also gave the 4N-co-ordinated derivative. However, reaction of biladien-bc-5-ones with NiII gave two compounds, one being the 4N-co-ordinated complex and other a side product in which the metal is co-ordinated to three pyrrole nitrogens of the conjugated system and to the meso-oxygen atom of the oxobiladiene [(3N + O) co-ordination].

https://dx.doi.org/10.1039/DT9960003937

π-Pyrrol-Metallkomplexe - der fehlende Koordinationstyp für Metall-Porphyrin-Wechselwirkungen

Senge, M. O., π-Pyrrol-Metallkomplexe - der fehlende Koordinationstyp für Metall-Porphyrin-Wechselwirkungen, Angew. Chem., 1996, 108, 2051-2053.

Metall-Porphyrin-π-Bindungen wie in 1 und 2 waren als Koordinationstyp in Komplexen bislang unbekannt. Derartige Arenkomplexe wurden kürzlich von Rauchfuss et al. synthetisiert (Angew. Chem. 1996, 108, 1985). Metall-Porphyrin-Wechselwirkungen dieser Art könnten auch bei den von Metalloporphyrinen katalysierten Reaktionen eine Rolle spielen.

https://dx.doi.org/(empty)

π-Pyrrole-Metal Complexes - The Missing Coordination Mode for Metal-Porphyrin Interactions

Senge, M. O., π-Pyrrole-Metal Complexes - The Missing Coordination Mode for Metal-Porphyrin Interactions, Angew. Chem. Int. Ed., 1996, 35, 1923-1925.

Metal—porphyrin π bonds such as those in 1 and 2 were hitherto unknown modes of coordination in porphyrin complexes. However, arene complexes of this kind were recently synthesized by Rauchfuss et al. (Angew. Chem. Int. Ed. Engl. 1996, 35, 1833). Metal — porphyrin interactions of this type may also play a role in reactions catalyzed by metalloporphyrins.

https://dx.doi.org/10.1002/anie.199619231

Synthesis and Structural Characterization of Lithium Thiolates: Dependence of Association and Aggregation on Donor Hapticity and Ligand Size and Synthesis of the First Trimeric Lithium Thiolate [Li(THF)SR]3 and the Solvent Separated Ion Pair [Li(12-crown-4)2][SR] (R = 2,4,6t-Bu3C6H2)

Ruhlandt-Senge, K., Englich, U., Senge, M. O. and Chadwick, S., Synthesis and Structural Characterization of Lithium Thiolates: Dependence of Association and Aggregation on Donor Hapticity and Ligand Size and Synthesis of the First Trimeric Lithium Thiolate [Li(THF)SR]3 and the Solvent Separated Ion Pair [Li(12-crown-4)2][SR] (R = 2,4,6t-Bu3C6H2), Inorg. Chem. 1996, 35, 5820-5827.

The synthesis and structural characterization of several lithium thiolates are reported. Formation of discrete species can be achieved by careful variation of ligand size and donor hapticity, as exemplified by the monomeric formulation of Li(PMDTA)STrityl (PMDTA = N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, Trityl = CPh3), 1, and Li(PMDTA)STrip, 2 (Trip = 2,4,6-iPr3C6H2), versus the dimeric species [Li(THF)2STrityl]2, 3, and [Li(TMEDA)STrip]2, 4 (TMEDA = N,N,N′,N′-tetramethylethylenediamine). By control of the stoichiometry of the donor, the first trimeric lithium thiolate [Li(THF)SMes*]3, 5 (Mes* = 2,4,6-tBu3C6H2), exhibiting a six-membered ring system and rare three-coordinate lithium centers, becomes available.

https://dx.doi.org/10.1021/ic960375e

Planare Bischlorophyllderivate mit vollständig konjugiertem π-System - Modellverbindungen für das Spezialpaar der Photosynthese

Jaquinod, L., Senge, M. O., Pandey, R. K., Forsyth, T. P. and Smith, K. M, Planare Bischlorophyllderivate mit vollständig konjugiertem π-System - Modellverbindungen für das Spezialpaar der Photosynthese, Angew. Chem., 1996, 108, 1982-1984.

Bei der Titan-induzierten Kupplung von NiII- und ZnII-Pyrophäophorbiden entstehen planare C=C-verbrückte Bisphiophorbide 1, M=Ni, Zn. Ihre Absorptionsspektren weisen auf eine starke Konjugation der beiden Chlorin-Einheiten hin, und aus Kristallstrukturanalysen geht hervor, daß die beiden Phäophorbidringe beinahe coplanar sind.

https://dx.doi.org/10.1002/ange.199618401

Planar Bischlorophyll Derivatives with a Completely Conjugated Π-System: Model Compounds for the Special Pair in Photosynthesis

Jaquinod, L., Senge, M. O., Pandey, R. K., Forsyth, T. P. and Smith, K. M., Planar Bischlorophyll Derivatives with a Completely Conjugated Π-System: Model Compounds for the Special Pair in Photosynthesis, Angew. Chem. Int. Ed., 1996, 35, 1840-1842.

The titanium-mediated coupling of NiII and ZnII pyrophaeophorbides results in formation of planar ethenefused bisphaeophorbides 1, M = Ni, Zn. Absorption spectroscopy indicates that the two chlorin units are highly conjugated, and the X-ray crystal structure shows the two phaeophorbide rings to be almost coplanar.

https://dx.doi.org/10.1002/anie.199618401

Synthesis and crystal structures of cofacial bischlorins. Octaethylchlorin-based structural models for the special pair in photosynthesis.

Senge, M. O., Kalisch, W. W. and Ruhlandt-Senge, K., Synthesis and crystal structures of cofacial bischlorins. Octaethylchlorin-based structural models for the special pair in photosynthesis. Chem. Commun., 1996, 2149-2150.

McMurry coupling of metalloformyloctaethylchlorins yields the first cofacial bischlorin with structural characteristics mimicking those of the special pair in photosynthesis.

https://dx.doi.org/10.1039/CC9960002149

Stepwise Syntheses of Bis-Porphyrins, Bis-Chlorins, Bis-Corroles, and of Porphyrin-Chlorin and Porphyrin-Corrole Heterodimers

Paolesse, R., Pandey, R. K., Forsyth, T. P., Jaquinod, L., Gerzevske, K. R., Nurco, D. J.; Senge, M. O., Liccocia, S., Boschi, T. and Smith, K. M, Stepwise Syntheses of Bis-Porphyrins, Bis-Chlorins, Bis-Corroles, and of Porphyrin-Chlorin and Porphyrin-Corrole Heterodimers, J. Am. Chem. Soc., 1996, 118, 3869-3882.

The stepwise syntheses and characterization of a series of symmetrical and unsymmetrical bisporphyrins, bischlorins, and biscorroles, and of porphyrin—chlorin and porphyrin—corrole dyads possessing ethylene, phenyl, and stilbene linking units are described. The methodology for synthesis of 10-substituted corroles 2 and their cobalt complexes 9 via a,c-biladiene salts 1 was first developed, and then extended to provide biscorroles (e.g., 4 and 5) linked through the 10-positions with phenyl linker units. Using a similar methodology, phenyl-linked corrole—porphyrin dyads 28 and 30 were also prepared. By way of intermediate phenyl-linked unsymmetrical bisdipyrromethanes, a completely unsymmetrical heterobimetallic bisporphyrin system, 45, was synthesized. Low-valent titanium coupling (McMurry) reactions were used to prepared stilbene-linked bisdipyrromethanes (e.g., 46) which were subsequently transformed into stilbene-linked bisporphyrins (e.g., 48).

https://dx.doi.org/10.1021/ja9541138

Simple Methodology for Syntheses of Porphyrins Possessing Multiple Peripheral Substituents with an Element of Symmetry

Nguyen, L. T., Senge, M. O. and Smith, K. M., Simple Methodology for Syntheses of Porphyrins Possessing Multiple Peripheral Substituents with an Element of Symmetry, J. Org. Chem., 1996, 61, 998-1003.

New methodology was developed for synthesis of regiochemically pure porphyrins with D2h symmetry (e.g. 9) via tetramerization reactions involving two different pyrroles. The two pyrrole components were a 2,5-diunsubstituted pyrrole (e.g. 11) and a 2,5-bis[(N,N-dimethylamino)methyl]pyrrole (e.g. 10), the latter being formed from a 2,5-di-unsubstituted pyrrole by treatment with excess Eschenmoser's reagent (N,N-dimethylmethyleneammonium iodide). A bis-butanoporphyrin 16 was transformed into the corresponding opp-bis-benzoporphyrin 17 by treatment with DDQ. The synthetic method was further extended to allow the synthesis of more unsymmetrical porphyrins, with C2v symmetry (e.g. 32), by reacting a tripyrrane (e.g. 27) with a 2,5-bis[(N,N-dimethylamino)methyl]pyrrole (e.g. 18). The structures and substituent arrays in both type of porphyrins were confirmed by single-crystal X-ray crystallography.

https://dx.doi.org/10.1021/jo951870f

Synthesis and structural characterization of nonplanar tetraphenylporphyrins with graded degree of β-ethyl substitution

Kalisch, W. W. and Senge, M. O., Synthesis and structural characterization of nonplanar tetraphenylporphyrins with graded degree of β-ethyl substitution, Inorg. Chem., 1997, 36, 6103-6116.

Different porphyrin conformations are believed to play a role in controlling the cofactor properties in natural tetrapyrrole—protein complexes. In order to study the correlation between macrocycle nonplanarity and physicochemical properties in detail, a series of six porphyrins with graded degrees of macrocycle distortion were synthesized via mixed condensation of pyrrole, diethylpyrrole, and benzaldehyde. The formal introduction of successively more Β-ethyl groups into the tetraphenylporphyrin parent macrocycle gave access to diethyltetraphenylporphyrin (H2DETPP), two regioisomers of tetraethyltetraphenylporphyrin (H2tTETPP, H2cTETPP), and hexaethyltetraphenylporphyrin (H2HETPP). These conformationally designed compounds bridge the gap between the well-known tetraphenylporphyrin (H2TPP) and the very nonplanar octaethyltetraphenylporphyrin (H2OETPP), which are also formed during the reaction. Crystallographic studies showed that the macrocycle distortion in the solid state increases gradually in the order TPP < DETPP < tTETPP < cTETPP < HETPP < OETPP, i.e. with increasing degree of Β-ethyl substitution and the number and localization of potential Β-ethyl meso-phenyl interactions.

https://dx.doi.org/10.1021/ic970765g

Crystal and molecular structures of some mono-meso-substituted free base and zinc(II)octaalkylporphyrins

Senge, M. O., Forsyth, T. P. and Smith, K. M., Crystal and molecular structures of some mono-meso-substituted free base and zinc(II)octaalkylporphyrins, Z. Kristallogr. Cryst. Mater, 1996, 211, 176-185.

Studies on highly substituted porphyrins bearing eight Β-substituents and at least one bulky meso-substitutent have shown that peripheral steric strain leads to considerable macrocycle distortion. While this is well established for porphyrins with dodecasubstitution; the situation is less clear for nonasubstituted porphyrins with meso-substituents such as methyl, aryl or ester groups. In order to further study this situation we have investigated the conformation of nonasubstituted porphyrins with small meso-substitutents by determination of the crystal structures of: 2,3,7,8,12,13,17,18-octaethyl-5-(N-succinimidyl)porphyrin, 1; 2,7,12,17-tetraethyl-3,8,13,18-tetramethyl-5-methoxymethylporphyrin, 2; Pyridine(2,7,12,17-tetraethyl-3,8,13,18-tetramethyl-5-methoxymethylporphyrinato)zinc(II), 3; methanol(5-acetoxy-2,7,12,17-tetraethyl-3,8,13,18-tetramethyl-porphyrinato)-zinc(II) methanol solvate, 4; and (2,3,7,8,12,13,17,18-octaethyl-5-methylporphyrinato)zinc(II), 5. The compounds show only small deviations from planarity which might be due to packing effects, however, all compounds show some degree of rhomboic elongation of the porphyrin core.[unk]

https://dx.doi.org/10.1524/zkri.1996.211.3.176

Bis(methanol-O)(2,3,7,8,12,13,17,18-octaethylporphyrinato-N,N',N'',N''')iron(III) Perchlorate Bis(methanol) Solvate, [FeIII(oep)(HOCH3)2](ClO4).2CH3OH

Senge, M. O., Bis(methanol-O)(2,3,7,8,12,13,17,18-octaethylporphyrinato-N,N',N'',N''')iron(III) Perchlorate Bis(methanol) Solvate, [FeIII(oep)(HOCH3)2](ClO4).2CH3OH, Acta Cryst., 1996, C52, 302-305.

Simple treatment of [FIII(oep)C1] (where oep is octaethylporphyrin) with dilute perchloric acid leads to facile preparation of the title compound, [Fe(C36H44N4) - (CH4O)2](ClOa).2CH40. The structure consists of dis- crete [Fe(oep)(HOCH3)2] + cations, perchlorate anions and methanol molecules of solvation, which are con- nected by hydrogen bonds in an infinite network. The Fe atom is located in the plane of the N atoms and is coordinated by two methanol O atoms in the axial po- sitions, with an average Fe--N distance of 2.026 (3) A and Fe--O bond lengths of 2.159 (3) A.

https://dx.doi.org/10.1107/S0108270195006068

Structure and Biosynthesis of Bacteriochlorophylls

Senge, M.; Senger, H., Structure and Biosynthesis of Bacteriochlorophylls, In: Anoxygenic Photosynthetic Bacteria, 1995, Vol. 2, (Blankenship, R. E.; Madigan, M. T.; Bauer, C. E., eds.), Kluwer Academic Publ., Dordrecht, pp. 137-151.

Anoxygenic Photosynthetic Bacteria is a comprehensive volume describing all aspects of non-oxygen-evolving photosynthetic bacteria. The 62 chapters are organized into themes of: Taxonomy, physiology and ecology; Molecular structure of pigments and cofactors; Membrane and cell wall structure: Antenna structure and function; Reaction center structure and electron/proton pathways; Cyclic electron transfer; Metabolic processes; Genetics; Regulation of gene expression, and applications. The chapters have all been written by leading experts and present in detail the current understanding of these versatile microorganisms.

https://dx.doi.org/(empty)

Structure and Conformation of Photosynthetic Pigments and Related Compounds 9 On the Structure and Macrocycle Conformation of Two Copper(II) Rhodochlorin Derivatives and Two Related Rhodoporphyrins

Senge, M. O., Ruhlandt-Senge, K., Lee, S.-J. H. and Smith, K. M. Structure and Conformation of Photosynthetic Pigments and Related Compounds 9 On the Structure and Macrocycle Conformation of Two Copper(II) Rhodochlorin Derivatives and Two Related Rhodoporphyrins, Z. Naturforsch. B, 1995, 50b, 969-981.

Crystal structure analyses of (rhodochlorinato-15-acetic trimethyl ester)copper(II) 3 and (S'^-didehydro-rhodochlorinato-lS-form ic acid trimethyl ester)copper(II) 4 reveal intriguing multiple macrocycle conformations of the metallochlorins in the crystal. The observed conformations range from almost planar macrocycles to distorted macrocycles with individual atoms being displaced up to 0.72 A from the mean plane.

https://dx.doi.org/10.1515/znb-1995-0620

Crystal Structure of a Remarkably Ruffled Nonplanar Porphyrin - (Pyridine)(5,10,15,20-Tetra(tert-butyl)porphyrinato)zinc(II)

Senge, M. O., Ema, T. and Smith, K. M., Crystal Structure of a Remarkably Ruffled Nonplanar Porphyrin - (Pyridine)(5,10,15,20-Tetra(tert-butyl)porphyrinato)zinc(II), J. Chem. Soc., Chem. Commun., 1995, 733-734.

The title compound presents the first example of a sterically ruffled porphyrin bearing only meso substituents; the degree of ruffling is severe, with Cm-displacements of up to 1 Å.

https://dx.doi.org/10.1039/C39950000733

Synthesis and Characterization of the Strontium Thiolate Sr(SMes*)2(THF)4·2THF (Mes* = 2,4,6-tBu3C6H2) and Selenolate Sr(SeMes*)2(THF)4·2THF. Structural Investigation of SrI2(THF)5

Ruhlandt-Senge, K., Davis, K., Dalal, S., Englich, U. and Senge, M. O., Synthesis and Characterization of the Strontium Thiolate Sr(SMes*)2(THF)4·2THF (Mes* = 2,4,6-tBu3C6H2) and Selenolate Sr(SeMes*)2(THF)4·2THF. Structural Investigation of SrI2(THF)5, Inorg. Chem. 1995, 34, 2587-2592.

The syntheses and structural characterization of the strontium thiolate Sr(SMes*)2(THF)4'2THF, 1 (Mes* = 2,4,6-tBu3C6H2), and selenolate Sr(SeMes*)2(THF)4′2THF, 2, are described. We also report the synthesis and structural characterization of Srl2(THF)s, 3, the apparent starting material for the synthesis of 1 and 2. 3 exhibits pentagonal bipyramidal geometry at the strontium atom. 3 can be prepared by dissolving Srl3 in THF, while the treatment of 3 with 2 equiv of the sterically demanding potassium thiolate and selenolate in THF affords 1 and 2 in good yields. 1 and 2 exhibit distorted octahedral environments at the metal center, with the degree of distortion much more significant for the thiolato derivative. 1

https://dx.doi.org/10.1021/ic00114a016

Synthesis and characterization of models for the bilin catabolites of chlorophylls using metallo-β-oxochlorins and -benzo[at]chlorins: comparison of macrocycle cleavage versus meso-oxochlorin formation

Isaac, M., Senge, M. O. and Smith, K. M, Synthesis and characterization of models for the bilin catabolites of chlorophylls using metallo-β-oxochlorins and -benzo[at]chlorins: comparison of macrocycle cleavage versus meso-oxochlorin formation, J. Chem. Soc., Perkin Trans. 1, 1995, 705-714.

Synthetic studies on meso-substitution and subsequent macrocycle ring-opening reactions have been performed on a 3-oxochlorin 7 and benzo[at]chlorin 19 to obtain access to bilins related to the natural chlorophyll catabolites 2 and 3. The zinc oxochlorin 8 could be trifluoroacetoxylated with thallium(III) trifluoroacetate in the 5-, 15- or 20-meso-positions. The 15-trifluoroacetoxy derivative 10 spontaneously ring-opened to give a bilintrione 13, which exhibited the same basic structural characteristic found in natural chlorophyll catabolites, namely macrocycle cleavage at a meso-position distant from (rather than adjacent to) the pyrrolenine ring. A single crystal structure analysis of 13 showed a linear conformation, indicating that a Z to E isomerization had taken place.

https://dx.doi.org/10.1039/P19950000705

Structure and Conformation of Photosynthetic Pigments and Related Compounds, 8 [1] Molecular Structure of an Iron(III) Chlorophyll Derivative-Chloro(phytochlorinato methyl ester)iron(III)

Senge, M. O., Ruhlandt-Senge, K. and Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds, 8 [1] Molecular Structure of an Iron(III) Chlorophyll Derivative-Chloro(phytochlorinato methyl ester)iron(III), Z. Naturforsch. B, 1995, 50b, 139-146.

The crystal and molecular structure of chloro(methyl phytochlorinato)iron(III), 4, have been determined by single crystal X-ray crystallography to obtain further information on the conformation of metallochlorins related to chlorophyll. The compound crystallized with two independent molecules mainly distinguished by the orientation of the axial ligand. The macrocycles show significant deviations from planarity larger than those observed in corresponding magnesium(II) complexes.

https://dx.doi.org/10.1515/znb-1995-0125

Models for the Photosynthetic Reaction Center - Preparation, Spectroscopy, Crystal and Molecular Structures of Cofacial Bisporphyrins Linked by cis-1,2- and trans-1,2-Ethene Bridges, and of 1,1-Carbinol Bridged Bisporphyrins

Senge, M. O., Vicente, M. G. H., Gerzevske, K. R., Forsyth, T. P. and Smith, K. M., Models for the Photosynthetic Reaction Center - Preparation, Spectroscopy, Crystal and Molecular Structures of Cofacial Bisporphyrins Linked by cis-1,2- and trans-1,2-Ethene Bridges, and of 1,1-Carbinol Bridged Bisporphyrins, Inorg. Chem.,1994, 33, 5625-5638.

The low-valent titanium induced reductive coupling of metal(II) 5-formyl-octaethylporphyrin (OEP) (2, 3) leads to the formation of ethene-bridged bisporphyrins. Structural studies on the main products of the coupling of Cu(II) (2) and Ni(II) 5-formyl-OEP (3) revealed, surprisingly, the formation of the cn-isomers 1,2-bis[5-(2,3,7,8,- 12,13,17,18-octaethylporphyrinato)metal(II)]-cz5-ethene (4, 5). This is in contrast to other reported reductive couplings of aldehydes and ketone which usually lead to the rrazu-product. The dr-isomer can undergo an acidcatalyzed isomerization to the trans-isomer (6, 7) which is also formed as a side product in the coupling reaction. An explanation for the formation of the ds-ethene-bridged bisporphyrins may involve the strong aggregation tendencies of metalloporphyrins

https://dx.doi.org/10.1021/ic00103a006

Sterisch gespannte Porphyrine. - Einfluß der Kernprotonierung und der peripheren Substitutenten auf die Konformation von tetra-meso-, octa-β-und dodekasubstituierten Porphyrin-Dikationen

Senge, M. O., Forsyth, T. P., Nguyen, L. T. and Smith, K. M., Sterisch gespannte Porphyrine. - Einfluß der Kernprotonierung und der peripheren Substitutenten auf die Konformation von tetra-meso-, octa-β-und dodekasubstituierten Porphyrin-Dikationen, Angew. Chem., 1994, 106, 2554-2557.

Das am stärksten sattelförmig verbogene Porphyrin , das bislang charakterisiert wurde, ist das Dikation [H4obrtpp]2+ (H2obrtpp = Octabromtetraphenylporphyrin). Seine Pyrrolringe sind in der Verbindung [H4obrtpp][CF3COO]2.5 CHCI3 im Kristall um 62° gegeneinander gekippt, und die Β-Pyrrol-C-Atome sind mehr als 1.5 ä von der mittleren Ebene des Porphyrinrings entfernt. Diese extreme Verbiegung ist die Folge der sterisch anspruchsvollen Substituenten an der Porphyrinperipherie und der vier Protonen im Zentrum des Gerüstes.

https://dx.doi.org/(empty)

Sterically Strained Porphyrins. Influence of Core Protonation Versus Peripheral Substitution on the Conformation of Tetra-meso-, Octa-β-, and Dodecasubstituted Porphyrin Dications

Senge, M. O., Forsyth, T. P., Nguyen, L. T. and Smith, K. M., Sterically Strained Porphyrins. Influence of Core Protonation Versus Peripheral Substitution on the Conformation of Tetra-meso-, Octa-β-, and Dodecasubstituted Porphyrin Dications, Angew. Chem. Int. Ed. Engl., 1994, 33, 2485-2487.

The saddle-shaped porphyrin with the largest deviation from planarity observed to date is found in the crystal structure of [H4obrtpp][CF3COO]2 · 0.5 CHCl3 (H2obrtpp = octabromotetraphenylporphyrin). The pyrrole rings in the porphyrin are twisted by 62° with respect to each other, and the Β-pyrrole C atoms are displaced by over 1.5 Å from the mean plane of the porphyrin ring. This extreme distortion is caused by the bulky peripheral substituents on the porphyrin ring and the four protons at the core of the structure.

https://dx.doi.org/10.1002/anie.199424851

One-pot synthesis of regiochemically pure porphyrins from two different pyrroles

Nguyen, L. T., Senge, M. O. and Smith, K. M., One-pot synthesis of regiochemically pure porphyrins from two different pyrroles, Tetrahedron Lett., 1994, 35, 7581-7584.

Treatment of 2,5-di-unsubstituted pyrroles (e.g. 10) with excess of Eschenmoser's reagent (N,N-dimethylmethyleneammonium iodide) affords 2,5-bis-(N,N-dimethylaminomethy)pyrroles (e.g. 7); reaction with a second 2,5-di-unsubstituted pyrrole (e.g. 8) gives pure porphyrin (e.g. 9) with identical substituents on opposite pyrrole sub-units. 2,5-Bis-(N,N-dimethylaminomethyl)pyrroles 7 react with 2,5-di-unsybstituted pyrroles (e.g. 8), under carefully controlled conditions to give so-called opp-porphyrins (e.g. 9) in which like pyrrole rings are regiochemically situated opposite to each other.

https://dx.doi.org/10.1016/S0040-4039(00)78348-1

5,10,15,20-Tetra-(tert -butyl)porphyrin und seine bemerkenswerte Reaktivität in 5,15-Stellung

Ema, T., Senge, M. O., Nelson, N. Y., Ogoshi, H., and Smith, K. M., 5,10,15,20-Tetra-(tert -butyl)porphyrin und seine bemerkenswerte Reaktivität in 5,15-Stellung, Angew. Chem., 1994, 106, 1951-1953.

Wegen des Raumbedarfs der tert-Butylgruppen weicht die Reaktivität des neuartigen Porphyrins 1 mit nichtplanarem makrocyclischem Grundgerüst von der aller bekannten Porphyrine ab. So führt längere Behandlung von 1 mit HClO4/MeOH zur Bildung des 5,15-Dihydroporphyrins (″Porphodimethens″) 2.

https://dx.doi.org/(empty)

5,10,15,20-Tetra-(tert-butyl)porphyrin and Its Remarkable Reactivity in the 5- and 15-Position

Ema, T., Senge, M. O., Nelson, N. Y., Ogoshi, H., and Smith, K. M., 5,10,15,20-Tetra-(tert-butyl)porphyrin and Its Remarkable Reactivity in the 5- and 15-Position, Angew. Chem. Int. Ed. Engl., 1994, 33, 1879-1881.

Owing to the steric bulk of the tert-butyl groups, the reactivity of the novel porphyrin 1, which has a nonplanar macrocyclic framework, deviates distinctly from that of any other known porphyrin. For example, prolonged treatment of 1 in HClO4/MeOH leads to formation of 5,15-dihydroporphyrin (″porphodi-methene″) 2.

https://dx.doi.org/10.1002/anie.199418791

Conformational Study of 2,3,5,7,8,12,13,17,18-Decaalkylporphyrins

Medforth, C. J., Senge, M. O., Forsyth, T. P., Hobbs, J. D., Shelnutt, J. A. and Smith, K. M., Conformational Study of 2,3,5,7,8,12,13,17,18-Decaalkylporphyrins, Inorg. Chem., 1994, 33, 3865-3872.

X-ray crystal structures are reported for two sterically crowded porphyrins; 3,5,7,13,15,17-hexaethyl-2,8,12,18- tetramethylporphyrin (6, H2DAP) and (3,5,7,13,15,17-hexaethyl-2,8,l 2,18-tetramethylporphinato)nickel(II) (Ni6, NiDAP). In the NiDAP structure, steric crowding is relieved by the usual mechanism of the porphyrin adopting a nonplanar conformation. The crystal structure of H2DAP is unusual, as it shows an essentially planar conformation of the porphyrin macrocycle. In this case, steric crowding of the meso and pyrrole ethyl groups is relieved by a novel elongation of the macrocycle along the 5,15 axis. A detailed study is made of the solution conformations of H2DAP, NiDAP, and the corresponding zinc(II) complex (ZnDAP), using optical spectroscopy, variable-temperature proton NMR spectroscopy, and molecular mechanics calculations.

https://dx.doi.org/10.1021/ic00096a008

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 7. On the Conformation of the Methyl Ester of (20-Methyl-phytochlorinato)nickel(II) - A Bacteriochlorophyll c Model Compound

Senge, M. O. and Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 7. On the Conformation of the Methyl Ester of (20-Methyl-phytochlorinato)nickel(II) - A Bacteriochlorophyll c Model Compound, Photochem. Photobiol., 1994, 60, 139-142.

Abstract The crystal and molecular structure of the title compound 4 have been determined by single crystal X-ray crystallography. The structure shows the typical S,-ruffled conformation observed for Ni(II) tetrapyrroles. Compared to the structure of the methyl ester of (132-demethoxycarbonyl-pheophorbidato a)nickel(II), 4 shows a smaller Ca-Cm-Cm angle and a higher degree of conformational distortion at the methyl-substituted C20 position. This local distortion of the macrocycle might account for the bathochromic shifted absorption spectra of the bacteriochlorophylls c compared to the d-series. Crystal data: C35H38N4NiO3; tetragonal, P43212, a = 15.335(7) Å, c = 25.11(2) Å, V = 5904, Z = 8, Λ(Mo KΑ) = 0.71069 Å, Μ= 0.701 mm—1, P(000) = 2624, 130 K, R = 0.058 for 5700 reflections with F > 4.0Σ(F).

https://dx.doi.org/10.1111/j.1751-1097.1994.tb05080.x

Benzoporphyrin Derivatives: Synthesis, Structure, and Preliminary Biological Activity

Meunier, I., Pandey, R. K., Senge, M. O., Dougherty, T. J. and Smith, K. M., Benzoporphyrin Derivatives: Synthesis, Structure, and Preliminary Biological Activity, J. Chem. Soc., Perkin Trans. 1, 1994, 961-969.

Starting from hematoporphyrin-IX dimethyl ester 1, a series of isomerically pure so-called benzoporphyrin derivatives (BPDs)20, 23—25, 27, 28, 31—33, 35—37, 39, 40, 42, 44 and 45 have been synthesized. The bis-porphyrins 46 and 47 with carbon—carbon linkages were also prepared by treating 3- and 8-(1-hydroxyethyl)benzoporphyrin derivatives 24 and 32 with triflic acid. In preliminary in vivo studies, the hexyl ether derivatives 27, 35, 40 and 45(as diastereoisomeric mixtures) appear to have better photosensitizing efficacy than the benzoporphyrin derivative monocarboxylic acid (BPD-MA; mixture of 21 and 22).

https://dx.doi.org/10.1039/P19940000961

Axial Coordination Phenomena in Highly Substituted Porphyrins. Crystal Structure of the Polymeric (2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrinato)zinc(II), [{Zn(oetnp)}n]

Senge, M. O. and Smith, K. M., Axial Coordination Phenomena in Highly Substituted Porphyrins. Crystal Structure of the Polymeric (2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrinato)zinc(II), [{Zn(oetnp)}n] J. Chem. Soc., Chem. Commun., 1994, 923-924.

The polymeric structure of the sterically strained and non-planar porphyrin [{ZnIIoetnp}n] is determined by X-ray crystallography; polymerization is achieved by utilization of the nitro-groups for axial ligation to the zinc(II) centre.

https://dx.doi.org/10.1039/C39940000923

Syntheses, Structure, Properties, and Chemistry of 1,1-Di(pyrrolyl)ethenes

Xie, H., Lee, D. A., Senge, M. O. and Smith, K. M., Syntheses, Structure, Properties, and Chemistry of 1,1-Di(pyrrolyl)ethenes, J. Chem. Soc., Chem. Commun., 1994, 791-792.

Reaction of a 2-unsubstituted pyrrole with acetic anhydride and stannic chloride unexpectedly promotes self-condensation to give symmetrical di(pyrrolyl)ethene as a side-product in 6—10% yield, but overall yields of these 1,1-di(pyrrolyl)ethenes can be improved to 66% using a rational alternate route; structure and chemistry of 1,1-di(pyrrolyl)ethenes 2 are discussed.

https://dx.doi.org/10.1039/C39940000791

Prevention of Out-of-Plane Macrocycle Distortion by Thallium in the Sterically Strained 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin

Senge, M. O., Prevention of Out-of-Plane Macrocycle Distortion by Thallium in the Sterically Strained 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin, J. Chem. Soc., Dalton Trans., 1993, 3539-3549.

Dodecaalkyl/aryl-substituted porphyrins have been shown to exhibit severely non-planar macrocycle conformations with displacement of the Cb-atoms of up to 1.2 Å. 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin (H2oetnp) presents an easily available model compound for studies on the conformational flexibility of tetrapyrroles. In contrast to most known structures of dodecasubstituted porphyrins, which exhibit severely non-planar macrocycle conformations, the thallium(III) complex [Tl(oetnp)Cl], shows only a moderately distorted macrocycle with an average displacement of the Cb-atoms of 0.19 Å. This is the first example of a dodecasubstituted porphyrin where the effect of the large main-group metal ion counterbalances the conformational distortion induced by steric strain of the peripheral substituents.

https://dx.doi.org/10.1039/DT9930003539

Synthesis and Characterization of Thallium(III)halogeno and Pseudohalogeno Porphyrin Complexes - Variation of the Coordination Geometry as a Function of the Axial Ligand in Thallium(III) Porphyrins

Senge, M. O., Ruhlandt-Senge, K., Regli, K. J. and Smith, K. M., Synthesis and Characterization of Thallium(III)halogeno and Pseudohalogeno Porphyrin Complexes - Variation of the Coordination Geometry as a Function of the Axial Ligand in Thallium(III) Porphyrins, J. Chem. Soc., Dalton Trans., 1993, 3519—3538.

Several thallium(III) porphyrin complexes [Tl(por)X] with the axial ligand x = MeCO2, CF3CO2, Cl, Br, l, CN, SCN or N3, have been obtained via ligand-exchange reactions from the corresponding thallium(III) trifluoroacetates. All compounds were characterized by 1H NMR, UV/VIS spectroscopy, and elemental analysis. Fourteen compounds were investigated in detail by X-ray crystallography to obtain information on the influence of the axial ligand on the macrocycle core conformation in main-group metalloporphyrins and to establish the molecular stereochemistry of thallium(III) porphyrins with cyano, acetato, thiocyanato, bromo, iodo and azido groups as axial ligands.

https://dx.doi.org/10.1039/dt9930003519

Rational Tetra-Arylporphyrin Syntheses: Tetra-Arylporphyrins from the MacDonald Route

Wallace, D. M., Leung, S. H., Senge, M. O. and Smith, K. M, Rational Tetra-Arylporphyrin Syntheses: Tetra-Arylporphyrins from the MacDonald Route, J. Org. Chem., 1993, 58, 7245—7257

Four new synthetic routes to meso-tetraarylporphyrins using a MacDonald-type 2 + 2 condensation are described. Self-condensation of a 5-aryldipyrromethane (e.g., 17) with an aryl-substituted onecarbon bridging unit affords a mixture of tetraarylporphyrins due to acid-catalyzed redistribution reactions. The second and third methods presented here show wide applicability for the preparation of 5,10,15,20-tetraaryl-substituted porphyrins (e.g., 31, 37, 48, 49) with 2-fold rotational symmetry and involve self-condensation of 5-aryl- 1-aryldipyrromethanecarbinols. Finally, the fourth approach involves a 2 + 2 approach in which one of the two dipyrromethanes bears both of the bridging carbons in the porphyrin products, affording porphyrin 50 which possesses three different aryl rings, with one pair of uniquely opposite identical aryl groups. The last two 2 + 2 methods are further extended to give a tetraarylporphyrin 38 bearing four different aryl groups in a predesignated array, the structure of which is confirmed by a single-crystal X-ray study.

https://dx.doi.org/10.1021/jo00077a056

Aggregation of 2,3-Dihydroxy-Etiochlorin I - An Amphiphilic Model Compound for Photodynamic Therapy and Green Heme d

Senge, M. O., Hope, H., Iakovides, P. and Smith, K. M., Aggregation of 2,3-Dihydroxy-Etiochlorin I - An Amphiphilic Model Compound for Photodynamic Therapy and Green Heme d, Photochem. Photobiol., 1993, 58, 748—752.

The crystal structure of 2,3-dihydroxy-etiochlorin I has been determined to obtain information on its aggregation behavior. Cis-dihydroxychlorins serve as model compounds for green heme d and show promising photonecrotic activity in photodynamic therapy. The compound shows strong aggregation in the solid state facilitated by intramolecular hydrogen bonding between one hydroxy group and pyrrole nitrogens of neighboring molecules. This novel type of aggregation leads to chain-type aggregates in the crystal.

https://dx.doi.org/10.1111/j.1751-1097.1993.tb04963.x

Metal Complexes of Dioxo-Porphyrins - Zinc(II) Complexes of 5,15-Dioxo-2,3,7,8,12,13,17,18-octaethyl-porphyrin and 5,15-dioxo-etioporphyrin I

Senge, M. O. and Smith, K. M., Metal Complexes of Dioxo-Porphyrins - Zinc(II) Complexes of 5,15-Dioxo-2,3,7,8,12,13,17,18-octaethyl-porphyrin and 5,15-dioxo-etioporphyrin I, Z. Naturforsch. B, 1993, 48, 991—999.

The crystal structures of two zinc(II) 5,15-dioxo-porphyrins (porphodimethenes) have been determined to investigate the coordination chemistry of porphyrins with interrupted conjugation system. Both compounds have a five-coordinated zinc center with pyridine as axial ligand and show overall structural parameters very similar to porphyrins. The oxidized meso-positions are, however, easily identified by longer Cm- C a bond lengths and smaller Ca- C m- C a angles.

https://dx.doi.org/10.1515/znb-1993-0724

Aggregation Properties of Nitro-Porphyrins - Comparisons between Solid State and Solution Structures

Senge, M. O., Eigenbrot, C. W., Brennan, T. D., Shusta, J., Scheidt, W. R. and Smith, K. M., Inorg. Chem., Aggregation Properties of Nitro-Porphyrins - Comparisons between Solid State and Solution Structures, 1993, 32, 3134—3142.

Previous NMR spectroscopic studies on the aggregation properties of metalloporphyrins suggested that monosubstituted octaethylporphyrin (OEP) derivatives with substituents capable of inducing charge polarization form tail-to-tail type dimers in solution. Such dimers have implications as model compounds for the photosynthetic reaction center. Crystallographic studies on a series of 5-NO2-OEP compounds show that the zinc(II) complexes can indeed form dimers of the proposed type in the solid state. A four-coordinated planar zinc(II) 5-nitrooctaethylporphyrin and the corresponding methanol complex showed strong aggregation in the solid state.

https://dx.doi.org/10.1021/ic00066a027

Molecular Structure of the Copper(II) Complex of 20-Methoxy-mesoporphyrin IX Dimethyl Ester - A Model for the Enol-Form of Oxophlorins.

Senge, M. O.; Smith, K. M., Molecular Structure of the Copper(II) Complex of 20-Methoxy-mesoporphyrin IX Dimethyl Ester - A Model for the Enol-Form of Oxophlorins, Z. Naturforsch., 1993, 48b, 821—825.

The crystal structure of the title compound was determined to obtain structural information on asymmetric tetrapyrroles bearing an sp3-hybridized meso-oxygen atom. These types of compounds serve as models for the enol-form of oxophlorins, which often are obtained in crystalline form only with rotational disordering of the oxofunction, making conformational analyses difficult. C37H42CuN4O5, monoclinic, P21/n, a = 15.025(7), b = 9.204(3), c = 23.544(9) Å, Β = 94.33(4)°, V = 3246.7(13) Å3, 130 K, Z = 4, R = 0.075 for 3186 reflections with I > 2.0 Σ(I). The structure is characterized by a planar tetracoordinated copper(II) and an almost planar macrocycle.

https://dx.doi.org/10.1515/znb-1993-0618

Models for the Photosynthetic Reaction Center - Synthesis and Structure of Porphyrin Dimers with cis-Ethene and trans-Ethene and Skewed Hydroxy-Methylene Bridges.

Senge, M. O.; Gerzevske, K. R.; Vicente, M. G. H.; Forsyth, T. P.; Smith, K. M., Models for the Photosynthetic Reaction Center - Synthesis and Structure of Porphyrin Dimers with cis-Ethene and trans-Ethene and Skewed Hydroxy-Methylene Bridges, Angew. Chem., Int. Ed., 1993, 32, 750—753. Modelle für das photosynthetische Reaktionszentrum: Synthese und Struktur von cis- und trans-Ethen-verbrückten sowie gewinkelten Hydroxymethylen-verbrückten Porphyrindimeren, Angew. Chem., 1993, 105, 745—747.

TiCl3-induced coupling of meso-forrnylporphyrins provides cofacial porphyrin dimers such as 1 (M Cu, Ni) with bridging cis-CHCH units. These compounds show strong interactions between the porphyrin rings; in the case of M Ni, the dimer can be easily transformed into the corresponding trans isomer. Similar reactions with Β-formyl-porphyrins lead to a third type of dimer, a skewed hydroxymethylene-bridged bisporphyrin. These dimeric compounds are models for the photosynthetic reaction center and should facilitate studies on the influence of the dimer geometry on the photophysical properties.

https://dx.doi.org/10.1002/anie.199307501

A Novel 2,18-Bridged Biliverdin Derivative.

Sturrock, E. D.; Bull, J. D.; Kirsch, R. E.; Pandey, R. K.; Senge, M. O.; Smith, K. M., A Novel 2,18-Bridged Biliverdin Derivative, J. Chem. Soc., Chem. Commun., 1993, 872—874.

Base-catalysed dehydrohalogenation of a 3,18-bis(2-ohloroethyl)biliverdin 1 affords a novel 3-vinylbiliverdin 3 in which the 2- and 18-positions are bridged with a propano-tether; the structure of 3 has been established using single crystal X-ray and 1H nuclear Overhauser effect studies.

https://dx.doi.org/10.1039/C39930000872

A Planar Dodecasubstituted Porphyrin.

Senge, M. O.; Medforth, C. J.; Sparks, L. D.; Shelnutt, J. A.; Smith, K. M., A Planar Dodecasubstituted Porphyrin, Inorg. Chem., 1993, 32, 1716—1723.

Structural investigations of copper and nickel complexes of dodecasubstituted porphyrins bearing aryl groups at the meso positions and propano rings at the pyrrole 0 positions reveal considerable differences in their macrocycle conformations. While the nickel complex NiTC5T(3,4,5-OMeP)P was found to exhibit a nonplanar conformation which is considerably more planar than that of other dodecasubstituted porphyrins, the corresponding copper complex CuTC5T(3,4,5-OMeP)P was planar. CuTC5T(3,4,5-OMeP)P thus represents the first example of a completely planar dodecasubstituted porphyrin.

https://dx.doi.org/10.1021/ic00061a030

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 5. Structural Investigation of Nickel(II) Bacteriopetroporphyrins Related to the Bacteriochlorophylls c and d. Evidence for Localized Conformational Distortion in the c-Series.

Senge, M. O.; Smith, N. W.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 5. Structural Investigation of Nickel(II) Bacteriopetroporphyrins Related to the Bacteriochlorophylls c and d. Evidence for Localized Conformational Distortion in the c-Series, Inorg. Chem., 1993, 32, 1259—1265.

The structural investigation of three bacteriopetroporphyrins related to bacteriochlorophylls c and d reveals a localized distortion of the porphyrin macrocycle in the c-series at the meso-substituted C(20) position. This presents a structural rationale for the differences observed in reactivity and absorption spectra between bacteriochlorophylls bearing a C(20) methyl group and those without. The crystal structures determined for the Ni(I1) bacteriopetroporphyrins present the first such analysis for geoporphyrins derived from bacteriochlorophylls of the green sulfur bacteria.

https://dx.doi.org/10.1021/ic00059a038

Chemical synthesis of a ″GSA-pyrrole″ and its reaction with Ehrlich's reagent

Liddell, P. A.; Forsyth, T. P.; Senge, M. O.; Smith, K. M., Chemical synthesis of a "GSA-pyrrole" and its reaction with Ehrlich's reagent, Tetrahedron, 1993, 49, 1343—1350.

A rational chemical synthesis of 4-acetyl-2-(2-carboxyethyl)-5-methylpyrrole (5), the product formed when glutamate-1-semialdehyde (GSA, 2) is reacted with acetylacetone in the first step of the quantitative analysis for GSA in biological media. Rates of reaction of the GSA-pyrrole (5) with Ehrlich's reagent (the second step in GSA quantitation) are compared with the rates of the reactions of well-characterized ″ALA-pyrroles″ (3) and (4). Pyrrole (5) reacts more slowly with Ehrlich's reagent, and extinction coefficients for the corresponding Ehrlich's adducts were determined to be 46,000 for (3) and 865 for (5). These observations resolve the discrepancies observed in earlier quantitations of GSA and allow more accurate determinations of it in biological materials.

https://dx.doi.org/10.1016/S0040-4020(01)90187-5

Metal-Dependence of the Nonplanar Distortion of Octaalkyl-Tetraphenylporphyrins.

Sparks, L. D.; Medforth, C. J.; Park, M.-S.; Chamberlain, J. R.; Ondrias, M. R.; Senge, M. O.; Smith, K. M.; Shelnutt, J. A., Metal-Dependence of the Nonplanar Distortion of Octaalkyl-Tetraphenylporphyrins, J. Am. Chem. Soc., 1993, 115, 581—592.

The biological activity of porphyrins and related tetrapyrroles in proteins may be modulated by nonplanar conformational distortions; consequently, two aspects of nonplanarity have been investigated in the highly nonplanar octaalkyltetraphenylporphyrins (OATPPs). In the first part, the effect of the central metal ion (M = Ni(II), Co(II), Cu(II), Zn(II), Co(III), Fe(II1)) on the conformation of the OATPP macrocycle has been determined. Crystallographic studies reveal that the sterically encumbered, nonplanar porphyrin 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (OETPP) remains sufficiently flexible to show a small decrease in nonplanarity for large metal ions.

https://dx.doi.org/10.1021/ja00055a030

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 6. The First Crystal Structure of a Covalently-linked Chlorin Dimer - 20,20'-Ethylene-bis(2,3,7,8,12,13,17,18-trans-octaethyl-chlorin).

Senge, M. O.; Hope, H.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 6. The First Crystal Structure of a Covalently-linked Chlorin Dimer - 20,20'-Ethylene-bis(2,3,7,8,12,13,17,18-trans-octaethyl-chlorin), J. Chem. Soc., Perkin Trans., 1993, 2, 11—16.

The crystal structure of the title compound 1 has been determined by X-ray diffraction methods to obtain structural information on covalently-linked chlorin dimers as biomimetic models for the photosynthetic reaction centre. The dimer crystallizes in two different crystal forms. Both forms show different macrocycle conformations which indicates the conformational flexibility of the chlorin macrocycle. This shows that not only the overall structural similarity but also conformational parameters have to be considered in the design of reaction centre models. Crystal data: Form A: C74H98N8·CH2Cl2, monoclinic, space group C2/cwith a= 32.610(9)Å, b= 10.804(2)Å, c= 21.185(5)Å, Β= 108.90(6)°, and V= 7063(3)Å3, Z = 4. R= 0.073 (120 K). Form B: C74H98N8, monoclinic, space group C2/cwith a= 24.068(14)Å, b= 10.216(6)Å, c= 26.44(3)Å, Β= 92.19(6)°, V= 6497(7)Å3, Z= 4. R= 0.063 (130 K).

https://dx.doi.org/10.1039/p29930000011

Recent Advances in the Biosynthesis and Chemistry of the Chorophylls.

Senge, M. O., Yearly Review. Recent Advances in the Biosynthesis and Chemistry of the Chorophylls, Photochem. Photobiol., 1993, 57, 189—206.

The field of chlorophyll (Chl)* biosynthesis and characterization remains one of the most actively pursued areas in photobiology. Much progress has been made in our understanding of the biosynthesis of Chl with much of the recent impetus coming from enzymology and molecular biology. Nevertheless, although the main pathway leading to Chl a is fairly well understood, our knowledge of the biosynthetic interrelationship of the different Chl and their intermediates, formation of the bacteriochlorophylls (bChl), regulation, and degradation is still limited.

https://dx.doi.org/10.1111/j.1751-1097.1993.tb02276.x

New Syntheses of benzoporphyrin derivatives and analogues for use in photodynamic therapy.

Meunier, I.; Pandey, R. K.; Walker, M. M.; Senge, M. O.; Dougherty, T. J.; Smith, K. M., New Syntheses of Benzoporphyrin Derivatives and Analogues for Use in Photodynamic Therapy, Bioorg. Med. Chem. Lett., 1992, 2, 1575—1580.

An efficient route for the synthesis of isomerically pure benzoporphyrin derivative (BPD) is presented. To understand more about structure/activity relationships in photodynamic therapy, a series of BPD derivatives, including dimers linked with carbon-carbon bonds were also prepared. The structure of the most effective (ring A) BPD isomer (14) was confirmed by a single crystal X-ray study. New syntheses of pure ″benzoporphyrin derivative″ ring isomers, as well as dimer analogues (e.g. 23) are reported.

https://dx.doi.org/10.1016/S0960-894X(00)80433-3

Nonplanar distortion modes for highly substituted porphyrins.

Medforth, C. J.; Senge, M. O.; Smith, K. M.; Sparks, L. D.; Shelnutt, J. A., Nonplanar Distortion Modes for Highly Substituted Porphyrins, J. Am. Chem. Soc., 1992, 114, 9859—9869.

The syntheses, structures, and spectroscopic properties of some novel dodecaphenyl- and dodecaalkylporphyrins have been investigated with the aim of designing model compounds to aid in evaluating theoretical models of porphyrin nonplanarity. It was found that dodecaphenylporphyrin (3) and the dodecaalkylporphyrins 4a-c could be prepared using standard synthetic procedures and that these porphyrins adopted very distorted nonplanar structures in the crystalline state.

https://dx.doi.org/10.1021/ja00051a019

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 4. Two Crystal Forms of a Chlorin - Rhodochlorin XV Dimethyl Ester.

Senge, M. O.; Ruhlandt-Senge, K.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 4. Two Crystal Forms of a Chlorin - Rhodochlorin XV Dimethyl Ester, Acta Crystallogr. C, 1992, 48, 1810—1815.

Two different crystal forms of the title compound, (2S)-trans-methyl 8-ethenyl- 13-ethyl-2,3- dihydro- 18-methoxycarbonyl-3,7,12,17-tetramethyl21H,23H-porphine-2-propionate, were found and investigated by single-crystal X-ray crystallography. Triclinic form: C34H38N404.CH2C12, Mr = 647.6, P1, a = 9.879 (4), b = 10.648 (6), c = 16.059 (8) A, a = 97.29 (5), _fl = 94.24 (4), y = 96.97 (4) °, V = 1656.3 (14) A 3, Z = 2, Dx = 1.300 Mg m -3, a(Mo Ka) = 0.7107 A, /~ = 0.237 mm-1, F(000) = 680, T = 130 K, R = 0.075 for 3496 reflections with I > 2o,(/). This form crystallizes with one methylene chloride of solvation in antiparallel oriented layers, stacked by Π-Π interaction.

https://dx.doi.org/10.1107/S0108270192001999

Resonance Raman Spectroscopy of Non-Planar Nickel Porphyrins.

Shelnutt, J. A.; Hobbs, J. D.; Majumder, S. A.; Sparks, L. D.; Medforth, C. J.; Senge, M. O.; Smith, K. M.; Miura, M.; Quirke, J. M. E., Resonance Raman Spectroscopy of Non-Planar Nickel Porphyrins, J. Raman Spectrosc., 1992, 23, 523—529.

Non-planar conformational distortions have recently been implicated in the biological activity of porphyrins and related tetrapyrroles in proteins, and several studies have used highly substituted porphyrins to model these nonplanar conformational distortions. Several aspects of non-planarity in the highly substituted metalloporphyrins are discussed, focusing on resonance Raman spectroscopy as a technique for investigating these structural issues.

https://dx.doi.org/10.1002/jrs.1250231004

The conformational flexibility of tetrapyrroles - Current model studies and photobiological implications.

Senge, M. O., The conformational flexibility of tetrapyrroles - Current model studies and photobiological implications, J. Photochem. Photobiol., B: Biol., 1992, 16, 3—36.

Porphyrins and other tetrapyrroles exhibit a considerable flexibility of the macrocycle conformation. Examples of non-planar tetrapyrrole conformations have been observed in a variety of protein complexes, such as chlorophyll-reaction center and antenna systems, heme proteins and cytochromes. Different macrocycle conformations are believed to be responsible for diverse functions of the same chromophore in different protein environments. This allows an explanation of the spectral properties of antenna complexes and the unidirectionality of electron transfer in reaction centers to be given. The concept of conformational flexibility is reviewed with special attention given to the current work on model compounds for chlorophylls.

https://dx.doi.org/10.1016/1011-1344(92)85150-S

Structural Investigations on Mono- and Di-Acrolein Substituted Ni(II) Porphyrins and a Ni(II) Benzochlorin. Model Compounds for Photosensitizers in Photodynamic Therapy.

Senge, M. O.; Vicente, M. G. H.; Parkin, S. R.; Hope, H.; Smith, K. M., Structural Investigations on Mono- and Di-Acrolein Substituted Ni(II) Porphyrins and a Ni(II) Benzochlorin. Model Compounds for Photosensitizers in Photodynamic Therapy, Z. Naturforsch., 1992, 47b, 1189—1202.

The structures of four Ni complexes and a free base related to tetrapentanoporphyrin (TC7P) and octaethylporphyrin (OEP) have been determined by X-ray crystallograpic methods. The Ni(II) complexes exhibit considerable S4-ruffling induced by coordination hole contraction due to the low spin Ni(II). The degree of conformational distortion is enhanced by one or two additional acrolein substituents at the meso positions. The steric strain imposed by interaction of the meso substituent with the neighboring Β-pyrrole substituents leads to a significant displacement from the mean plane of the molecule of the meso carbon(s) involved.

https://dx.doi.org/10.1515/znb-1992-0822

Structural Evidence for Nonplanar Keto- and Planar Enol-Forms of Oxophlorins.

Senge, M. O.; Smith, K. M., Structural Evidence for Nonplanar Keto- and Planar Enol-Forms of Oxophlorins, J. Chem. Soc., Chem. Commun., 1992, 1108—1109.

The first structural investigation of a zinc(II) and a free-base oxophlorin reveals considerable conformational differences between the keto-(1) and enol-form (2) of oxophlorins.

https://dx.doi.org/10.1039/c39920001108

Oxoporphyrins - The Molecular Structure of 5,15-Dioxo-2,3,7,8,12,13,17,18-octaethyl-porphodimethene-thallium(III) Chloride.

Senge, M. O.; Smith, K. M., Oxoporphyrins - The Molecular Structure of 5,15-Dioxo-2,3,7,8,12,13,17,18-octaethyl-porphodimethene-thallium(III) Chloride, Z. Naturforsch., 1992, 47b, 837—841.

The crystal structure of the title compound was determined in order to obtain structural information on a tetrapyrrole bearing meso-oxo-functions. C36H42N4O2T1C1 · CH3OH, P1, a = 10.358(2), b = 12.344(3), c = 15.490(3) Å, a = 84.36(2)°, Β = 78.53(2)°, Γ = 82.26(2)°, V = 1918.2(7) Å3, Z = 2, 130 K, R = 0.04 for 6749 reflections with I > 4Σ(Ι). The structure consists of the penta-coordinated thallium ligated by the four nitrogens of the porphodimethene ligand and a chloride in the axial position. The central macrocycle shows some degree of ruffling with the carbonyl groups pointing slightly above and below the mean plane of the molecule.

https://dx.doi.org/10.1515/znb-1992-0613

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 3. ß-Carotene.

Senge, M. O.; Hope, H.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 3. ß-Carotene, Z. Naturforsch., 1992, 47c, 474—476.

The crystal structure o f the title compound (C40H 56, Mw = 536.8) has been redetermined by X-ray diffraction methods in order to achieve a structure at higher resolution suitable for theoretical calculations. The crystal system is monoclinic, P21/n, a = 7.656(2), b = 9.445(5), c - 23.536(15) ä, ß = 93.41(2)°, V = 1698.8(15) ä 3, Z = 2, D = 1.050 m g/m 3, 130 K. R = 0.071, Rw = 0.076.

https://dx.doi.org/10.1524/zkri.1992.199.14.239

Struktur und Biosynthese der Bakteriochlorophylle.

Senge, M. O., Struktur und Biosynthese der Bakteriochlorophylle, Chem. unserer Zeit, 1992, 26, 86—93.

Bakteriochlorophylle gehören zu der großen Gruppe der Metallotetrapyrrole. Als photosynthetische Pigmente sammeln sie Licht und überführen die Lichtenergie in biochemisch nutzbare Form. Damit stehen Bakteriochlorophylle an zentraler Stelle in einem Elementarprozeß der Natur.

https://dx.doi.org/10.1002/ciuz.19920260209

8,12-Diethyl-2,3,7,13,17,18-hexamethyl-20-phenylporphyrin

Senge, M. O.; Liddell, P. A.; Smith, K. M., 8,12-Diethyl-2,3,7,13,17,18-hexamethyl-20-phenylporphyrin, Acta Crystallogr. C, 1992, 48, 581—583.

C36H38N4, Mr = 526.7, orthorhombic, Iba2, a=12.870(6), b=55.71(3), c=7.837(2) A, V= 5619 (4) A 3, Z = 8, Dx = 1.245 Mg m -3, a(Mo Ka) = 0.7107 A, /z = 0.069 mm- 1, F(000) = 2256, T = 130 K, R = 0.076 for 1428 independent reflections [I> 2tr(/)]. The title compound consists of the slightly ruffled porphyrin macrocycle with the phenyl substituent oriented 84.6° out of the plane of the N atoms.

https://dx.doi.org/10.1107/S0108270191010338

Structure and conformation of photosynthetic pigments and related compounds. 1. Methyl mesopyropheophorbide a.

Senge, M. O.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 1. Methyl Mesopyropheophorbide a, Z. Kristallog., 1992, 199, 239—248.

The crystal structure of the title compound (5) (C34H38N4O3, M(w) = 550.7) has been determined by X-ray diffraction methods in order to determine the influence of the carbomethoxy group on ring V upon the aggregation behaviour of chlorophylls. The crystals are green parallelpipeds and crystallize in the orthorhombic space group P2(1)2(1)2(1) with a = 8.120(6), b = 14.431(10), c = 24.405(8) angstrom, V = 2860(3) angstrom 3, Z = 4, D = 1.279 Mg/m3. lambda(MoK-alpha) = 0.71069 angstrom, mu = 0.077 mm-1, F(000) 1176, 130 K. The final R value is 0.055 for 1338 observed reflections. The molecules are closely packed by interactions of the propionic ester side chains with each other and by close contacts of the C10-meso-proton with the carbonyl group on ring V.

https://dx.doi.org/10.1524/zkri.1992.199.3-4.239

Structure and Conformation of Photosynthetic Pigments and Related Compounds. 2. Ni(II) Methyl pyropheophorbide a - A Severly Distorted Chlorophyll Derivative.

Senge, M. O.; Smith, K. M., Structure and Conformation of Photosynthetic Pigments and Related Compounds. 2. Ni(II) Methyl pyropheophorbide a - A Severly Distorted Chlorophyll Derivative, Photochem. Photobiol., 1991, 54, 841—846.

The crystal structure of Ni(II) methyl pryopheophorbide a (3) (CMH34N4Ni03, Mu= 605.4) was determined by x-ray diffraction methods in order to determine the influence of the nickel-ion on the ring conformation. The crystals were blue octahedrons and crystallized in the tetragonal space group P4121,2 with a= 14.727(4) Å, c = 26.666(12) Å, V= 5781(3) Å3Z= 8, D= 1.391 mg/m3. (Mo KΑ) = 0.71069 ÅΜ= 0.713 mm—1, F(000) = 2544, 130 K. The final R value was 0.064 for 4096 observed reflections, wR = 0.065. The molecule is severely distorted and shows a saddle-shaped ring conformation, the Β-pyrrole atoms being displaced up to 0.6 A out of the plane of the nitrogens. The severe deformation restricts the use of Ni-derivatives in spectroscopic model studies on chlorophylls and provides an example for the conformational flexibility of the phorbin macrocycle.

https://dx.doi.org/10.1111/j.1751-1097.1991.tb02099.x

Preparation and Crystal Structure of Methyl (12-Acetyl-8-ethyl)- bacteriopheophorbide d. - A New Bacteriochlorophyll Derivative.

Senge, M. O.; Bobe, F. W.; Huster, M. S.; Smith, K. M., Preparation and Crystal Structure of Methyl [12-Acetyl-8-ethyl]-Bacteriopheophorbide d - A New Bacteriochlorophyll Derivative, Liebigs Ann., 1991, 871—874.

The mechanism of the oxidation of (I) to give the title compound (II) is elucidated by experiments with 18O2. The implication of this mechanism for the biosynthesis of the bacteriochlorophylls is discussed. The crystal structure of (II) (P1, Z = 2) is assigned by X- ray diffraction.

https://dx.doi.org/10.1002/chin.199148222

Adaptation of the Photosynthetic Apparatus of Chlorella and Ankistrodesmus to Blue and Red Light

Senge, M.; Senger, H., Adaptation of the photosynthetic apparatus of Chlorella and Ankistrodesmus to blue and red light, Bot. Acta, 1991, 104, 139—143.

The mode of adaptation of the photosynthetic apparatus of three unicellular green algae, Ankistrodesmus braunii, Chlorella fusca and Chlorella saccharophila to red and blue light are documented by the fluence-rate curves of photosynthetic oxygen evolution. For all three algae tested photosynthetic capacity, respiration and light compensation point were higher for cells grown under red light, while the chlorophyll content increased in blue light-grown cells. Blue light-adapted cells have a lower chlorophyll a to chlorophyll b ratio and more chlorophyll in the light-harvesting system than red light-adapted cells, as shown in the electrophoretic profile of the pigment-protein complexes. It is concluded that the action of red light resembles that of high levels of white light, while blue light causes the same effects as low levels of white light. In agreement with previous publications these findings indicate that the mode of adaptation to different light qualities is ubiquitous in unicellular green algae.

https://dx.doi.org/10.1111/j.1438-8677.1991.tb00209.x

Functional changes in the photosynthetic apparatus during light adaptation of the green alga Chlorella fusca

Senge, M.; Senger, H., Functional changes in the photosynthetic apparatus during light adaptation of the green alga Chlorella fusca, J. Photochem. Photobiol., B: Biol., 1990, 8, 63—71.

Cells of the unicellular green alga Chlorella fusca adapt to a low intensity (5 W m—2) of white light or to blue light (DAL 444 nm filter; 7.5 Μmol m—2 s—2) by increasing the amount of chlorophyll and lowering the photosynthetic capacity and respiration rate in comparison with cells adapted to a high intensity (20 W m—2) of white light or red light (AL 683 nm filter; 7.5 Μmol m—2 s—2) respectively. The change in adaptation of the alga from one light condition to the other takes about 8 h. Changes in molecular organization of the photosynthetic apparatus of cells adapting to low intensities of white light result in doubling the photosystem I and II units, whereas adaptation to blue light increases the light-harvesting complex of photosystem II preferentially. These results confirm the findings with Scenedesmus.

https://dx.doi.org/10.1016/1011-1344(90)85188-3

Response of the Photosynthetic Apparatus during Adaptation of Chlorella and Ankistrodesmus to Irradiance Changes

Senge, M.; Senger, H., Response of the Photosynthetic Apparatus During Adaptation of Chlorella and Ankistrodesmus to Irradiance Changes, J. Plant Physiol., 1990, 136, 675—679.

Cultures of Ankistrodesmus braunii, Chlorella fusca and Chlorella saccharophila were grown under high (20 W · m-2) and low (5 W · m-2) intensities of white light. For all three strains respiration, photosynthetic capacity and light intensity at which the compensation point was reached were higher, whereas chlorophyll and carotenoid concentration were almost half in cultures adapted to high light intensities. No significant changes in the pigment composition or distribution of pigment protein complexes could be observed. It was concluded that the cells adapted to lower light intensities by doubling the pigment apparatus, as observed in Scenedesmus and higher plants. Changing from one intensity to the other, the photosynthetic apparatus adapted within 6—8 h to the new condition.

https://dx.doi.org/10.1016/S0176-1617(11)81343-X

Aggregation of Monovinyl- and Divinyl-Protochlorophyllide in Organic Solvents

Kotzabasis, K.; Senge, M.; Seyfried, B.; Senger, H., Aggregation of Monovinyl- and Divinyl-Protochlorophyllide in Organic Solvents, Photochem. Photobiol., 1990, 52, 95—101.

Two different protochlorophyllides (PChlide), PChlide 629/433 (absorption data in methanol) and PChlide 630/441 (the monovinyl (MV) and divinyl (DV) forms) were isolated from the pigment mutant C-2A' of Scenedesmus obliquus. Their spectroscopic behaviour in several organic solvents and their aggregation in toluene was investigated. In polar solvents such as ether, acetonitril or acetone, absorption maxima similar to those in methanol were observed, while in solvents such as tetrahydrofuran and pyridine a bathochromic shift of the blue absorption band compared to the spectra in methanol occurred. The absorption maxima of MV-PChlide shifted from 629 nm and 433 nm in methanol (monomeric form), to 631 nm and 443 nm in toluene (aggregated form).

https://dx.doi.org/10.1111/j.1751-1097.1990.tb01761.x

Determination of structure and properties of modified chlorophylls by using fast atom bombardment combined with tandem mass spectrometry

Synthese und Charakterisierung chlorierter Chlorophylle. Wissenschaftliche Forschungsbeiträge Biologie/Biochemie/Chemie, Band 26, Intemann, Gauting bei München, ISBN 3-926323-30-2.

Tandem mass spectrometry (MS/MS) was used to investigate and compare the decompositions of radical cations (M+′), radical anions (M—′), [M + H]+ ions, and [M + Cat]+ ions (Cat = alkali metal ions) of chlorophylls. Included in this study are chlorophyll a, chlorophyll b, bacteriochlorophyll a, chlorophyll a allomers, and the corresponding pheophytins.

https://dx.doi.org/10.1016/1044-0305(90)80008-B

Enzymic meso-chlorination of chlorophylls using chloroperoxidase

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Chlorophyll a could be chlorinated enzymically by a chloroperoxidase (EC 1.11.1.10; chloride:hydrogen-peroxide oxidoreductase) from the fungus imperfectus Caldariomyces fumago. Analyses with 1H-NMR, mass spectrometry, fluorescence emission and absorption spectroscopy, and chemical demetallation showed the product to be 20-chlorochlorophyll a. This product was formed regioselectively in about 80% yield.

https://dx.doi.org/10.1016/S0005-2728(89)80069-6

Synthese und Charakterisierung chlorierter Chlorophylle

Senge, M., Synthese und Charakterisierung chlorierter Chlorophylle, in Wissenschaftliche Forschungsbeiträge Biologie/Biochemie/Chemie, 1989, Band 26, Intemann, Gauting bei München, ISBN 3-926323-30-2.

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https://dx.doi.org/(empty)

Enzymatic Chlorination of Chlorophyll a in vitro.

Senge, M.; Senger, H., Enzymatic Chlorination of Chlorophyll a in vitro, In: New Developments and Techniques in Photosynthesis, NATO ASI Series, Series A Life Sciences, 1989, Vol. 168, (Barber, J.; Malkin, R., eds.), Plenum Press, New York, pp. 119—122.

Chlorinated chlorophylls (chl) came into focus in recent years with reports suggesting the participation of 13''-HO-20-Cl-chl a in photosystem I <1,2>. However, studies revealed the artificial formation of this compound <3,4>. Nevertheless chlorinated chlorophylls deserve further attention, since their unique physical and chemical properties make them promising model compounds for comparative chl studies.

https://dx.doi.org/10.1007/978-1-4684-8571-4_11

Chlorination of Isolated Chlorophylls in vitro

Senge, M.; Senger, H., Chlorination of Isolated Chlorophylls in vitro, Photochem. Photobiol., 1988, 48, 711—717.

It was shown that chlorophyll a and its epimer chlorophyll a' are chlorinated and hydroxyl-ated during thin layer chromatography with silica gel plates. Hydroxylated chlorophyll a could not be chlorinated. Chlorinated and non chlorinated chlorophylls could be separated and determined by high performance liquid chromatography, because chlorophylls do not alter during this procedure. These findings support the assumption that Chi RC I is a preparation artifact. The extent of chlorination depends on chloride availability on the thin layer and on time. Chlorination and hydroyxlation do not take place under nitrogen atmosphere. The mechanism of chlorination during the thin layer chromatography procedure is discussed.

https://dx.doi.org/10.1111/j.1751-1097.1988.tb02885.x

Hydroxylation of Chlorinated and Unchlorinated Chlorophylls in vitro

Senge, M.; Struck, A.; Dörnemann, D.; Scheer, H.; Senger, H., Hydroxylation of Chlorinated and Unchlorinated Chlorophylls in vitro, Z. Naturforsch., 1988, 43c, 515—518.

Chlorophyll a is hydroxylated quantitatively in the 13''-position, when chromatographed on silica gel thin-layer plates. This was shown by using HPLC as a non-destructive method für analyzing photosynthetic pigments. The hydroxy-group of Chl RC I, a 13''-hydroxy-20-chloro-chl a, described by Dörnemann and Senger (1986) and Scheer et al. (1986), is shown to be artificially introduced during the purification procedure by TLC.

https://dx.doi.org/10.1515/znc-1988-7-807

The chlorinated chlorophyll RC I, a preparation artefact.

Senge, M.; Dörnemann, D.; Senger, H., The chlorinated chlorophyll RC I, a preparation artefact, FEBS Lett., 1988, 234, 215—217.

A special chlorophyll, designated chlorophyll RC I, has been reported by our and other laboratories to be a stable chlorophyll, extractable from organisms with oxygenic photosynthesis. Its structure was revealed as 13''-hydroxy-20-chloro-chlorophyll a. We revise the finding that chlorophyll RC I is a naturally occurring chlorophyll, and show that it is an artificial chlorination product created during thin-layer chromatography on silica gel. Simultaneous hydroxylation prevents further chlorination and stabilizes the already chlorinated chlorophylls. Avoiding TLC by applying HPLC we were unable to find chlorinated chlorophylls in pigment extracts and, therefore conclude that chlorophyll RC I is an artefact generated during thin-layer chromatography.

https://dx.doi.org/10.1016/0014-5793(88)81337-1

Chlorophyll RC I, its Structure, Function, and Biosynthesis

Senger, H.; Dörnemann, D.; Kotzabasis, K.; Senge, M.; Schmidt, W.; Wissenbach, M., Chlorophyll RC I, its Structure, Function, and Biosynthesis, In: Progress in Photosynthesis Research, (Biggens, J., ed.), Vol. IV, Martinus Nijhoff Publ., Dordrecht, pp. 491—498.

In all photosynthetic organisms the bulk of pigments is designated to collect light energy and to funnel this energy to reaction centers, in which the primary charge separation takes place. Compared to the mass of antenna pigments, the chromophores capable for charge separation in the reaction centers amount only to about 0.5% or less. Whereas the antenna pigments of organisms with oxygenic photosynthesis are well characterized as chlorophylls a and b, phycobilins and in some cases carotenoids, little is known about the nature, arrangement and action of their reaction center pigments.

https://dx.doi.org/10.1007/978-94-017-0519-6_100