Journal of Porphyrins and Phthalocyanines

Three copper triarylcorroles containing a $\beta$-pyrrole nitro substituent were synthesized and characterized as to their spectral and electrochemical properties in nonaqueous media. The examined compounds are represented as $\beta$-NO₂(YPh)₃CorCu, where Cor is the trianion of a triphenylcorrole and Y is a Cl, H or CH₃ substituent at the para-position of the three meso-phenyl rings of the compound. The data from absorption spectra, electrochemistry and thin-layer spectroelectrochemistry are consistent with an initial assignment of Cu${}^{II}$-Cor${}^{•2-}$ in CH₂Cl₂, DMF and pyridine and electrogeneration of a formal Cu(II) corrole with an unreduced macrocycle, represented as Cu${}^{II}$-Cor${}^{3-}$, after the first one-electron reduction in these solvents. The doubly reduced $\beta$-nitrocorrole has a sharp Soret band at 439 nm and a well-defined Q-band at 611 nm in CH₂Cl₂. Similar absorption spectra are seen for the three examined doubly reduced nitrocorroles in DMF and pyridine, suggesting formation of a Cu(I) species with an unreduced macrocycle which is represented as Cu${}^I$-Cor${}^{3-}$. Changes in redox potentials and absorption spectra of the nitrocorroles are examined as a function of solvent and substituents on the meso-phenyl rings of the compounds and comparisons are made between spectral and electrochemical data of the newly synthesized corroles and that of structurally related tetraarylcorroles lacking a $\beta$-nitro group.

The influence of porphyrin molecules configuration on their ability to affect on DNA structure were investigated for water-soluble cationic meso-tetra-(3N-hydroxyethylpyridyl) porphyrin (H₂THOEtPyP3) and its metal complexes with Cu, Ni, Co, Zn using viscometry and UV-vis absorption spectroscopy. A comparative analysis was performed with the results of previously conducted similar studies of meso-tetra-(4N-hydroxyethylpyridyl) porphyrin (H₂THOEtPyP4). Viscosity measurements show that the change in position of peripheral radicals on pyridylic ring has absolutely no effect on the laws of interaction of investigated porphyrins with DNA in case of outside binders such as CoTHOEPyP3 and ZnTHOEPyP3. In the presence of planar porphyrins, such as CuTHOEPyP3 and NiTHOEPyP3 the laws of structural changes of DNA are the same as in the case of H₂THOEtPyP3, with some differences. Comparison of different locations of peripheral radicals on pyridylic rings leads to the conclusion that H₂THOEtPyP3 and its metal complexes bind to DNA preferably more than H₂THOEtPyP4 and its metal complexes. This fact may be explained only suggesting that porphyrins with hydroxyethyl groups at 3N-position are favorably located relative to the DNA helix axis than at 4N-position.

A series of porphyrins with directly meso-attached “sucrose” moiety by the carbon C-6′ of its “fructose” end was synthesized, and their physico-chemical and aggregation properties studied by spectroscopic (fluorescence, circular dichroism, resonance light scattering) techniques. The effect of selected porphyrins on tumor cells was also evaluated.

Synthesis of two trans-dihydroxy platinum(IV) porphyrins (TPP, tetraphenylporphyrin and F${}_{20}$TPP, tetrakispentafluorophenylporphyrin) by dimethyl dioxirane (DMD) oxidation of their Pt${}^{II}$ porphyrin precursors have been described. The oxidation state of Pt cation in such complexes was assessed by X-ray photoelectron spectroscopy and shown to be $+$4. More importantly, proton was found to promote the formation and stabilization of the trans-dihydroxy platinum(IV) porphyrins, as revealed by UV-vis spectroscopic results and single crystal structures. In addition, these trans-dihydroxy Pt${}^{IV}$ porphyrins were much easier to be reduced than their Pt(II) counterparts and capable to transfer oxygen atom to triphenylphosphine and thioanisol, which is important for further application of Pt(IV) complexes in catalytic reactions.

Amino-substituted tetraphenylporphyrins (5,10,15,20-tetrakis(4′-aminophenyl)porphyrin, 5-(4′-aminophenyl)–10,15,20-triphenylporphyrin) and their copper complexes in dichloromethane and ethanol were electropolymerized by the cyclic voltammetry method and their electrochemical properties were studied. The polyporphyrin films obtained by electro-oxidation transmit electricity and possess semiconductor properties of different types. The poly-5,10,15,20-tetrakis(4′-aminophenyl)porphyrin films obtained from different solvents are similar to each other in chemical composition but different in morphology. The polyporphyrin film surface morphology was studied by AFM microscopy.

Novel tetrabenzocorrolazine green photosensitizer was designed and synthesized to enhance the solar energy-to-electricity conversion efficiency of dye-sensitized solar cells. This near-infrared absorbing dye exhibited superior short-circuit photocurrent density induced from the additional absorption compared to the phthalocyanine dye commonly applied as a photosensitizer covering the near-infrared region in dye-sensitized solar cells. The introduction of bulky peripheral groups and axial substituents to the novel dye led to the increase of open-circuit photovoltage. As a result, the novel tetrabenzocorrolazine dye achieved a solar energy-to-electricity conversion efficiency of 3.78% under AM 1.5G conditions which was much higher than that of the phthalocyanine reference dye.

The photosensitized protein-damaging activity of water-soluble freebase tetrakis($N$-methyl-$p$-pyridinio)porphyrin (H₂TMPyP), and its zinc complex (ZnTMPyP) was investigated using human serum albumin (HSA) as a target protein. These porphyrins bound to HSA and caused photosensitized oxidation of the tryptophan residue. The protein damage was enhanced in deuterium oxide and inhibited by sodium azide, a physical quencher of singlet oxygen, suggesting the contribution of singlet oxygen. However, an excess amount of sodium azide could not completely inhibit protein damage. These findings suggest the partial contribution of another mechanism to the protein damage, possibly the electron transfer mechanism. The Gibbs free energy of the electron transfer mechanism showed that electron transfer-mediated tryptophan oxidation by photoexcited H₂TMPyP is more advantageous than that by ZnTMPyP. Actually, the quantum yield of protein damage through electron transfer by H₂TMPyP was larger than that by ZnTMPyP. In addition, this study demonstrated that the association between porphyrin and protein plays an important role in photosensitized protein damage.

We have synthesized two novel phthalocyanines, (m-SF${}_5$PhO)${}_8$PcCu (7b) and (p-SF${}_5$PhO)${}_8$PcCu (7c), in order to investigate their flying-seed-like mesomorphism. Their phase transition behavior and the mesophase structure have been established by using a polarizing optical microscope, a differential scanning calorimeter, and a temperature-dependent small angle X-ray diffractometer. Very interestingly, the derivative (m-SF${}_5$PhO)${}_8$PcCu (7b) substituted a SF₅ group at $m$-position showed a Col${}_{ro}$(P2₁/a) ($=$ p2gg) mesophase from rt to 315.0${}^{\circ }$C, whereas the derivative (p-SF${}_5$PhO)${}_8$PcCu (7c) substituted a SF₅ group at $p$-position showed a crystalline (K) phase from rt to the decomposition temperature at ca. 336${}^{\circ }$C without showing mesomorphism. Thus, the novel phthalocyanine derivative (m-SF${}_5$PhO)${}_8$PcCu (7b) substituted a strong electron withdrawing SF₅ group at $m$-position shows only one columnar mesophase in a very wide temperature region from rt to 315.0${}^{\circ }$C. Furthermore, the Q-band wavelengths (672.2 and 672.1 nm) of the present (m-SF${}_5$PhO)${}_8$PcCu (7b) and (p-SF${}_5$PhO)${}_8$PcCu (7c) are shorter than that (680.3 nm) of the previous [(m-C${}_1$)PhO]${}_8$PcCu (5c) derivative. It can be attributed to strong electron withdrawing nature of the SF₅ group on the phenoxy group.

Synthesis and crystal structure analysis of meso-tetratolylporphyrins, 1–5 combined with computational Hirshfeld surface analysis were investigated. The crystal packing of porphyrins 1, 3 and 4 are arranged in an “orthogonal fashion” whereas 2 and 5 are in a “slip-stack or off-set fashion” through various intermolecular interactions. Compound 2 exhibits saddle geometry whereas 5 showed a domed geometry as evident from the single crystal X-ray diffraction studies. The enhancement of non-planarity in 2 is probably due to the presence of numerous intermolecular interactions caused by the presence of trifluoroacetate anions on both faces of the porphyrin in addition to the bulky bromine groups at the $\beta$-pyrrole positions. In 5, the non-planarity is merely due to the metal coordination at the porphyrin core as pentacoordinated Mn${}^{\text{III}}$ center with a chloro ligand in the axial position. Hirshfeld surface analysis was performed in order to analyze the various intermolecular interactions present in these porphyrins and the result was discussed.