Benzylic modifications of meso-alkyl-substituted porphyrins via oxidation with DDQ

The reactions at the benzylic positions of meso-alkyl-substituted porphyrins have been achieved via the reaction with DDQ in the presence of alcohol or water for the first time, and ethenyl porphyrins from methoxylated porphyrins and an acetoxy porphyrin from the hydroxyl porphyrin were prepared.     

Rh(III) porphyrins as building blocks for porphyrin coordination arrays: from dimers to heterometallic undecamers

The coordination chemistry of a Rh(III) porphyrin building block was investigated with a view to the construction of heterometallic arrays of porphyrins. The Rh(III) porphyrin was found to coordinate methanol in the solid state and weakly in CDCl(3) solution. Crystallization afforded five coordinate pi stacked Rh(III) porphyrins. The distribution of products from reaction of Rh(III) porphyrin with DABCO, 4,4'-bipyridine, and 4,4'-bipyrimidine could be displaced toward dimeric species by silica gel column chromatography or recrystallization which served to remove excess ligand. Weak coordination to nitriles was observed, although it was sufficiently strong to organize a dimeric complex of 5,5'-dicyano-2,2'-bipyridine in the solid state. Complexes with 4,4'-bipyrimidine and 5,5'-dicyano-2,2'-bipyridine possess uncoordinated chelating nitrogen atoms. Larger heterometallic porphyrin arrays were assembled using a combination of Sn(IV) and Rh(III) porphyrin coordination chemistry. A Sn(IV) porphyrin acted as a core around which were coordinated two isonicotinate groups, carboxylic acid functionalized porphyrins, or porphyrin trimer dendrons. Rh(III) porphyrins were coordinated to pyridyl groups at the periphery of these entities. In this way an eleven porphyrin array, with four different porphyrin metalation states, was assembled. The diamagnetic nature of both the Rh(III) and Sn(IV) porphyrins, the slow ligand exchange kinetics on the NMR time scale, and tight ligand binding permitted the porphyrin arrays to be analyzed by two-dimensional (1)H NMR techniques.     

Merging porphyrins with organometallics: synthesis and applications

The coordination chemistry of porphyrins has traditionally involved the ability of the porphyrin's tetrapyrrolic core to accommodate metal ions of varying charges and sizes, and on the organometallic chemistry of the resulting metalloporphyrins. However, the organometallic chemistry of porphyrins is not necessarily restricted to the metal bound in the porphyrin core, but can also be extended to the porphyrin periphery, be it through direct metalation of the porphyrin macrocycle at the meso or beta position, or by attachment to or merger of the porphyrin skeleton with ligands, followed by metalation. This Review focuses on the synthetic strategies used for porphyrins with peripheral metal-carbon bonds. The exciting results that have been produced underscore the importance and future potential of this field.     

Mechanistic aspects of photoinactivation of Candida albicans by exogenous porphyrins

The mechanism of photoinactivation of Candida albicans by 3.5 μM uncharged, cationic or anionic porphyrins under blue light (407-420 nm) was found to be dependent on the uptake of porphyrins into yeast cells, and was also dependent on the presence or absence of proteins in the photosensitization medium. In a very protein-rich medium, a decrease in viability was observed only with the uncharged porphyrin. Photoinactivation by uncharged or cationic porphyrins in a protein-poorer medium resulted in total eradication, whereas no significant decrease was observed with the anionic porphyrin. Phototreatment in PBS resulted in eradication with all three porphyrins. X-ray microanalysis after phototreatment by the uncharged or cationic porphyrins in the protein-poor medium exhibited ion loss, indicating cell-membrane damage. Transmission electron microscopy indicated cellular and chromosomal damage. No ion loss or cell damage was observed in this medium with the anionic porphyrin. The efficiency of photoeradication of C. albicans is dependent on porphyrin uptake, which might lead (upon illumination) to processes that facilitate the formation of reactive oxygen species that damage the cells. Uptake of charged porphyrins is dependent on protein quantity and quality in the photosensitization microenvironment. This fact must be taken into account when using charged photosensitizers.     

卟啉衍生物的合成与性能研究进展

卟啉化学是有机化学研究中不可或缺的一个方向。由于卟啉在结构上具有一个大的共轭体系,从而具有典型的芳香性。其具有优异的光电性能、独特的光动力治疗作用、高效的催化活性,并且广泛存在于血红素、叶绿素、维生素B_(12)、过氧化氢酶等有机生物分子中,所有这一切都吸引着科学家们进行深入研究。本文从取代卟啉、缩合卟啉以及扩环卟啉三个方面分别讨论了卟啉的研究进展,通过列举一系列经典的反应以及卟啉衍生物,总结了卟啉衍生物的合成方法及其发展方向。另外,文中还对于卟啉的一些特殊物理、化学和光电性质,做了重点介绍。本文旨在为卟啉的研究者们提供参考。     

DNA as supramolecular scaffold for porphyrin arrays on the nanometer scale

Tetraphenyl porphyrin substituted deoxyuridine was used as a building block to create discrete multiporphyrin arrays via site specific incorporation into DNA. The successful covalent attachment of up to 11 tetraphenyl porphyrins in a row onto DNA shows that there is virtually no limitation in the amount of substituents, and the porphyrin arrays thus obtained reach the nanometer scale (approximately 10 nm). The porphyrin substituents are located in the major groove of the dsDNA and destabilize the duplex by deltaT(m) 5-7 degrees C per porphyrin modification. Force-field structure minimization shows that the porphyrins are either in-line with the groove in isolated modifications or aligned parallel to the nucleobases in adjacent modifications. The CD signals of the porphyrins are dominated by a negative peak arising from the intrinsic properties of the building block. In the single strands, the porphyrins induce stabilization of a secondary helical structure which is confined to the porphyrin modified part. This arrangement can be reproduced by force-field minimization and reveals an elongated helical arrangement compared to the double helix of the porphyrin-DNA. This secondary structure is disrupted above approximately 55 degrees C (T(p)) which is shown by various melting experiments. Both absorption and emission spectroscopy disclose electronic interactions between the porphyrin units upon stacking along the outer rim of the DNA leading to a broadening of the absorbance and a quenching of the emission. The single-stranded and double-stranded form show different spectroscopic properties due to the different arrangement of the porphyrins. Above T(p) the electronic properties (absorption and emission) of the porphyrins change compared to room temperature measurements due to the disruption of the porphyrin stacking at high temperature. The covalent attachment of porphyrins to DNA is therefore a suitable way of creating helical stacks of porphyrins on the nanometer scale.     

Synthesis of Linear Amphipathic Porphyrin Dimers and Trimers: An Approach to Bilayer Lipid Membrane Spanning Porphyrin Arrays

A modular building-block approach has been developed for the construction of linear amphipathic porphyrin arrays. The reaction of meso-(trifluoromethyl)dipyrromethane and an aldehyde under the conditions of the two-step room temperature porphyrin synthesis affords the trans-substituted porphyrin (13-56% yields). A similar reaction with two different aldehydes provides access to porphyrins bearing two different functional groups. An ethyne porphyrin and an iodo porphyrin (either free base or zinc) are selectively joined via Pd(0)-catalyzed coupling reactions, affording a linear array with porphyrins in defined metalation states. Coupling of a zinc-porphyrin bearing iodo and ester groups with a free base porphyrin bearing ethyne and ester groups yielded the zinc-free base porphyrin dimer. Coupling of a bis-ethyne porphyrin with a porphyrin bearing iodo and ester groups afforded the porphyrin trimer. Cleavage of the esters yielded the amphipathic porphyrin dimer and trimer arrays. The arrays with adjacent zinc and free base porphyrins undergo efficient electronic energy transfer. Both amphipathic porphyrin arrays have been incorporated into L-alpha-phosphatidylcholine vesicles. This versatile synthetic strategy provides access to a family of porphyrin arrays for studies of photophysical processes in supramolecular assemblies.     

Rational syntheses of cyclic hexameric porphyrin arrays for studies of self-assembling light-harvesting systems.

Two new cyclic hexameric arrays of porphyrins have been prepared in a rational, convergent manner. The porphyrins in each cyclic hexamer are joined by diphenylethyne linkers affording a wheel-like array with a diameter of approximately 35 A. One array is comprised of five zinc (Zn) porphyrins and one free base (Fb) porphyrin (cyclo-Zn(5)FbU) while the other is comprised of an alternating sequence of two Zn porphyrins and one Fb porphyrin (cyclo-Zn(2)FbZn(2)FbU). The prior synthesis employed a one-flask template-directed process and afforded alternating Zn and Fb porphyrins or all Zn porphyrins. More diverse metalation patterns are attractive for manipulating the flow of excited-state energy in the arrays. The rational synthesis of each array employed three Pd-mediated coupling reactions with four tetraarylporphyrin building blocks bearing diethynyl, diiodo, bromo/iodo, or iodo/ethynyl groups. The final ring closure yielding the cyclic hexamer was achieved by reaction of a porphyrin pentamer + porphyrin monomer or the joining of two porphyrin trimers. In the presence of a tripyridyl template, the yields of the 5 + 1 and 3 + 3 reactions ranged from 10 to 13%. The 5 + 1 reaction in the absence of the template proceeded in 3.5% yield, thereby establishing the structure-directed contribution to cyclic hexamer formation. The 3 + 3 route relied on successive ethyne + iodo/bromo coupling reactions. One template-directed route to cyclo-Zn(2)FbZn(2)FbU employed a magnesium porphyrin, affording cyclo-Zn(2)FbZn(2)MgU from which magnesium was selectively removed. The arrays exhibit absorption spectra that are nearly the sum of the spectra of the component parts, indicating weak electronic coupling. Fluorescence spectroscopy showed that the quantum yield of energy transfer in toluene at room temperature from the Zn porphyrins to the Fb porphyrin(s) was 60% in cyclo-Zn(5)FbU and 90% in cyclo-Zn(2)FbZn(2)FbU. Two dipyridyl-substituted porphyrins, a Zn tetraarylporphyrin and a Fb oxaporphyrin, have been synthesized for use as guests in the cyclic hexamers, affording self-assembled arrays for light-harvesting studies.     

具有不同取代链长的卟啉衍生物LB膜的结构研究

本文研究了三种羧酸取代的四苯基卟啉衍生物在空气/Cd^2^+水溶液界面上所形成的单层膜及LB膜。这三种卟啉衍生物中, 一种没有脂链, 另外两种具有不同长度的脂链。由π-A等温线得到的平均表观分子面积相差很大。紫外-可见光谱表明, LB膜中卟啉的Soret吸收带相对于溶液的吸收均红移, 但红移程度不同。LB膜的偏振紫外-可见光谱表明, LB膜中三种卟啉衍生物的卟啉环具有基本一致的取向。运用亚相降低法得到了三种卟啉衍生物单层LB膜, 其紫外-可见光谱与用垂直提拉法得到的LB膜的紫外-可见光谱具有一致的特征。这些结果表明: 卟啉衍生物有无取代链及取代链长的不同对平均表观分子面积的大小和膜中环间的距离有影响, 但对环的取向没有影响。环的取向由环本身及环上的亲水取代基来确定。气/液界面上三种卟啉衍生物的单层膜中环也具有一致的取向, 且与LB膜中环的取向相差不大。提拉不会对膜中环的取向及膜的结构造成大的改变。     

位阻型金属卟啉的合成及其催化烷烃基化的反应

本文用平衡法制备了中位-四(3,5-二叔丁基-4-甲氧基等基)卟啉(T~D~T~B~M~OPP), 并制备了该卟啉的铁、锰、钴、锌、铜、镍的金属配合物。经红外光谱、电子光谱、核磁共振谱, 元素分析等确认了这些均未见报道的金属卟啉。考察了在温和条件下, 以T~D~T~B~M~O PP Fe^III C和T~D~T~B~M~O PP Mn^III Cl为了催化剂, PhIo为氧化剂, 在CH~2Cl~2中氧化n-C~6H~1~4的反应, 并将结果与别的催化剂进行了比较。     

Ex vivo Application of δ-Aminolevulinic Acid Induces High and Specific Porphyrin Levels in Human Skin Tumors: Possible Basis for Selective Photodynamic Therapy

Abstract— In photodynamic therapy with topically applied δ-aminolevulinic acid porphyrins are acting as photosensitiz-ers. The profile of porphyrin metabolites in normal or in neoplastic skin after administration of δ-aminolevulinic acid has not been determined in detail yet. Thus, to study porphyrin biosynthesis in human skin an organ culture model was developed. Explant pieces of normal skin, ker-atoacanthoma, and basal cell carcinoma were incubated with 1 niM δ-aminolevulinic acid for 36 h. Levels of δ-aminolevulinic acid, porphyrins and porphyrin metabolites were measured in tissues and supernatants. After incubation with δ-aminolevulinic acid, higher porphyrin levels were demonstrated in tumors as compared to normal skin. In supernatants, most of formed porphyrins, preferentially highly carboxylated porphyrin metabolites, were measured. The pattern of synthesized porphyrins differed between normal and neoplastic skin explants. In tissues of basal cell carcinomas protoporphyrin was preferentially shown and tissues of keratoacanthomas were characterized by a predominance of coproporphyrin as compared to normal skin. The results show that explant cultures offer an easy approach to examine the porphyrin biosynthesis of various tissues. The tumor-specific δ-aminolevulinic acid metabolism indicates additional porphyrin metabolites such as coproporphyrin apart from protoporphyrin as effective photosensitizers and may offer a novel approach to tumor-selective photodynamic damage.     

A new route to meso-formyl porphyrins

Prior syntheses of porphyrins bearing meso-formyl groups have generally employed the Vilsmeier formylation of an acid-resistant copper or nickel porphyrin. A new approach for the synthesis of free base porphyrins bearing one or two (cis or trans) meso-formyl substituents entails the use of a dipyrromethane bearing an acetal group at the 5-position, a dipyrromethane-1-carbinol bearing an acetal group at the 5-position or carbinol position, or a dipyrromethane-1,9-dicarbinol bearing an acetal group at a carbinol position. Treatment of the resulting meso-acetal-substituted free base porphyrin to gentle acidic hydrolysis yields the corresponding meso-formyl porphyrin.     

Endocyclic extension of porphyrin pi-system by interior functionalization of N-confused porphyrins

Internally alkynylated or cyanated N-confused porphyrins have been prepared, and these have been characterized by NMR, UV/Vis/NIR absorption, and X-ray analysis. The desired porphyrins have been synthesized by interconversion between an N-confused porphyrin and an N-fused porphyrin. In the case of terminal alkyne derivatives, intramolecular addition of a pyrrolic NH moiety to the triple bond occurred at ambient temperature to give etheno-bridged N-confused porphyrins. Significant bathochromic shifts in the absorbances of these compounds may be reasonably explained in terms of an increase in their HOMO energy levels due to effective overlap of the porphyrin pi-orbital and the bridged alkene pi-orbital. The corresponding rhodium(I) complexes have also been prepared, and these have been characterized by NMR and X-ray analysis.     

Diastereochemically controlled porphyrin dimer formation on a DNA duplex scaffold

DNA-porphyrin conjugates were designed and synthesized for the preparation of the conformationally controlled porphyrin dimer structures constructed on a d(GCGTATACGC)2. Porphyrin derivatives were introduced to the central TATpA sequence where p represents the phosphoramidate for the attachment of the free-base porphyrin (FbP) and zinc-coordinated porphyrin (ZnP), which allows contact of the two porphyrins in the minor groove. The porphyrin dimers were characterized using CD, UV-vis, steady-state, and time-resolved fluorescence spectroscopies, indicating that the porphyrins form face-to-face conformations. Also the co-facial conformation was confirmed by comparison with spectra of the non-self-complementary duplex containing one porphyrin moiety. Introduction of zinc into porphyrin moiety destabilized the duplex formation. Two diastereomers showed different thermal stabilities and affected the conformations of porphyrin dimers. The temperature-dependent assembly and the conformational change of the porphyrin dimer on the duplex DNA were observed in the UV-vis spectra, indicating that the dynamic movement of the porphyrin dimer occurs on the duplex. The results indicate that the porphyrin dimers of DNA-FbP conjugates are overlapped clockwise and are located in the minor groove of the usual B-form DNA backbone. The interaction and conformation of two porphyrin moieties are controlled by the following three factors: (1) temperature change during and after formation of the duplex porphyrins at lower temperature; (2) diastereochemistry of the phosphoramidates where porphyrins are connected via a linker; and (3) zinc ion coordination that destabilizes the interaction of porphyrins as well duplex formation.     

The coordination of bismuth by porphyrins

The coordination chemistry of porphyrins towards the complexation of bimuth(III) has been investigated. Although the insertion of bismuth is tedious in porphyrins such as octa-ethyl porphyrin (OEP) or tetra-tolyl porphyrin (TTP), we have demonstrated that simple modifications of the ligand, like the grafting of arms bearing either ester groups or acid functions, lead to stable complexes, resulting from a rapid complexation reaction.     

Preferential Relative Porphyrin Enrichment in Solar Keratoses upon Topical Application of ^-Aminolevulinic Acid Methylester

Topically applied δ-aminolevulinic acid is used efficiently for the treatment of solar keratoses by photodynamic therapy. Recent animal studies suggest that porphyrin sensitization of epithelial tissue is improved by using esters rather than free δ-aminolevulinic acid. The present study examines porphyrin metabolite formation after topical application of δ-aminolevulinic acid or δ-aminolevulinic acid methylester in human solar keratoses versus adjacent normal skin. Levels of total porphyrins, porphyrin metabolites and protein were measured in skin samples excised after 1 and 6 h. Higher levels of porphyrins were observed in solar keratoses than in normal skin with both substances. Maximum porphyrin levels were present in solar keratoses treated with δ-aminolevulinic acid for 6 h. However, the ratio of porphyrins in solar keratoses versus adjacent normal skin was higher with 8-aminolevulinic acid methylester. The pattern of porphyrins showed no significant difference between normal and afflicted skin, protoporphyrin being predominant. The results suggest that application of free δ-aminolevulinic acid may be more effective in sensitizing solar keratoses. However, treatment with 8-aminolevulinic acid methylester leads to a preferential enrichment of porphyrins within lesional skin.     

荧光光谱法研究卟啉与金属离子配位反应机理初探

本文用荧光光谱法初步研究了卟啉与金属离子配位反应机理和部分催化剂的催化机理.实验发现,在一定条件下,卟啉以一种与其主要存在形式不同的变形体H₂P^*存在,根据H₂P^*的存在和产生的条件,对卟啉与金属离子配位反应的一般条件作出了较为满意的阐述.     

Porphyrin architectures tailored for studies of molecular information storage

A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Zinc porphyrins tethered to Au(111) or Si(100) provide a benchmark for studies of information storage. Three sets of porphyrins have been synthesized for studies of the interplay of molecular design and charge-storage properties: (1) A set of porphyrins is described for probing the effect of surface attachment atom on electron-transfer kinetics. Each porphyrin bears a meso-CH2X group for surface attachment where X = OH, SAc, or SeAc. (2) A set of porphyrins is described for studying the effect of surface-charge density in monolayers. Each porphyrin bears a benzyl alcohol for surface attachment and three nonlinking meso substituents of a controlled degree of bulkiness. (3) A set of porphyrins is described that enables investigation of on-chip patterning of the electrolyte. Each porphyrin bears a formyl group distal to the surface attachment group for subsequent derivatization with a molecular entity that comprises the electrolyte. Taken together, this collection of molecules enables a variety of studies to elucidate design issues in molecular-based information storage.     

长脂肪碳链卟啉的合成及其LB膜的制备和气敏性质研究

1983年RuaudelTeixier［’j首先合成了两类具有长脂肪碳链的双亲性叶咐，其成膜性表明，它们可以形成良好的LB膜．M6hwald‘’修合成了不对称可成股叶琳，并对其膜结构和分子间作用进行了研究．Lecomte“‘等用钴叶琳和咪吐等衍生物以混合交替形式来模拟血红蛋白的吸氧及放氧过程，发现它可作为氧的载体．Tredgold［“报道了用铜、钻、镍、锰叶琳和无金属叶琳的LB膜元件对NO。、H。S和CO进行检测，发现铜叶琳对NO。有很高的敏感性，而对其它气体则无反应，显示出良好的选择性．本文在合成6种长脂肪碳链的双亲性叶琳化合物的基础上，…     

Fusing Porphyrins and Phospholes: Synthesis and Analysis of a Phosphorus‐Containing Porphyrin

A phosphole‐fused porphyrin dimer, as a representative of a new class of porphyrins with a phosphorus atom, was synthesized for the first time. The porphyrin dimer exhibits remarkably broadened absorption, indicating effective π‐conjugation over the two porphyrins through the phosphole moiety. The porphyrin dimer possesses excellent electron‐accepting character, which is comparable to that of a representative electron‐accepting material, [60]PCBM. These results provide access to a new class of phosphorus‐containing porphyrins with unique optoelectronic properties.