Journal of Porphyrins and Phthalocyanines

Two series of porphyrin liquid crystalline compounds, meso-tetra-[(p-alkacyloxy-m-ethyloxy)phenyl]porphyrin (TPAMEP), and [5-(p-alkacyloxy) phenyl-10,15,20-tri-phenyl] porphyrin (APTPP) are synthesized and display a hexagonal columnar discotic columnar (Col_h) phase. Their structure and properties were studied by elemental analysis, molar conductance, UV-visible and infrared spectra. Luminescence spectra of the compounds were discussed. Quantum yields of the Q band are in the region 0.007935-0.05847. The electrochemical studies show that the redox potentials do not change with the variation of the chain length. The surface photovoltage (SPV) response of the compounds was investigated by means of surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage spectroscopy (FISPS), and the bands are analogous with the UV-visible absorption spectra.

The results for aggregation equilibrium of metallophthalocyanines in buffer and buffer-pyridine solutions were obtained and generalized. The influence of specific interactions of the metallophthalocyanines with pyridine on their aggregation state in solution was estimated.

Bis(4-methylpyridine)phthalocyaninato ruthenium(II) has been synthesized. It was proved by single-crystal X-ray diffraction that the central Ru(II) atom is bonded to six N atoms in an elongated octahedral configuration, and the axial ligands have a significantly longer Ru-N bond distance, 2.101(4) Å, than the independent pyrrol Ru-N bond, 1.99 Å. Therefore, the axial ligands can be exchanged by other ligands. The ligand exchange reactions with diethyl pyridyl-4-phosphonate and diethyl pyridylmethyl-4-phosphonate were studied in high boiling-point solvents at elevated temperatures, ca 160 °C. Mono-ligand as well as double-ligand replaced complexes were obtained. The complexes have been isolated by column chromatography. These complexes have potential applications, such as in dye sensitized solar cells.

Metallophthalocyanines have been synthesized in a very short time with excellent yields in the presence of tetrabutylammonium bromide (TBAB) as an ionic liquid at 185 °C. The ionic liquid can be recycled for subsequent reactions without any appreciable loss of efficiency.

The large difference in the binding affinity of tetramethoxy-p-benzoquinone between 5,15-cis-bis(ureidophenyl)porphyrin and its zinc-porphyrin analogue enables construction of a reversible system in which tetramethoxy-p-benzoquinone moves between 5,15-cis-bis(ureidophenyl)porphyrin and the zinc-porphyrin as a quinone shuttle and a nitrate ion works as a chemical switch.

The synthesis and characterization of novel phthalocyanines containing o-carborane groups are described. These new tetrasubstituted phthalocyanines are of interest for the use in cancer therapy. The activities of the carboranyl substituted phthalocyanines were evaluated by the photooxidation of (S)-(−)-citronellol to give a high oxygen consumption comparable to the photosensitizers tetrasulfophthalocyanine zinc complexes.

Two iron complexes of a porphyrin dimer molecule were synthesized and studied at the air-water interface and in Langumir-Blodgett (LB) films. Surface pressure-area isotherm and UV-vis absorption spectroscopic studies revealed an interesting molecular switching behavior between the two iron porphyrin complexes under basic or acidic conditions. Such a reversible structural transition does not only occur in solution phase, but readily takes place in the deposited Langmuir-Blodgett films. Domains with strip or disk-like shapes were formed in the Langmuir films of the metalloporphyrin complexes when barbituric acid was added into the subphase, an indication of supramolecular network formation between the metalloporphyrin dimer and barbituric acid molecules. Magnetic property studies of the Langmuir-Blodgett films of the iron porphyrin complexes by magnetic force microscopy provide further insights into relationships between the magnetic response and molecular structures of the metalloporphyrin LB films.

Directly meso-meso linked, partially metallated porphyrin oligomers (dimer, trimer, bent trimer and tetramer) have been synthesized by condensation of meso-formylated porphyrins with pyrrole. The reaction could be useful in the construction of partially metallated, porphyrin arrays.

The MacDonald's [2 + 2] condensation of unsubstituted dipyrromethane and 3- or 4-hydroxyalkoxybenzoaldehydes afforded 5,15-meso-hydroxyalkoxyphenylporphyrins. The hydroxyl groups on the side chains were then transformed to tertiary amines via synthesis of the mesylate and substitution with the appropriate amines or aminoalcohols. Methylation of such products afforded a series of cationic porphyrins which have been tested in vitro as photodynamic agents against microorganisms, showing high antimicrobial activity.

Herein we report the utilization of fluorescence anisotropy to give rough hints on the conformation of three halogenated silicon-phthalocyanines with axially substituted polyethyleneglycol chains in solution. To deconvolute decay data sets from the instrumental response function a scanning fit algorithm was used, which facilitates the visualization of fitting accuracy and correlation of parameters of the assumed decay function. Moreover, to extend our investigation of photophysical properties in the nonlinear domain, the transient absorption in the picosecond range was measured and thus excited state absorption spectra are presented.