Coordinating Properties of Co(II) and Zn(II) Complexes with Sterically Hindered Porphyrins

Cobalt(II) and zinc(II) complexes with 5,15-di(o-methoxyphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra-n-buthylporphyrin and its capped analogues, where the MN₄ reaction site is shielded by bridging groups containing m-phenylene and dimethoxy-substitutedp-phenylene fragments, were synthesized. Equilibrium constants of additional coordination of pyridine and N-methylimidazole by these metalloporphyrins were determined at 298 K. It was found that steric distortion of the porphyrin core destabilizes extra complexes.     

Acid–base and coordination properties of <Emphasis Type="Italic">Meso</Emphasis>-substituted porphyrins in nonaqueous solutions

Acid–base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N–H bonds of porphyrin reaction centers. Dissociation constants pK _b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of pK _b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.     

Aza-substitution,benzo-annulation effects and catalytic activity of <Emphasis Type="Italic">β</Emphasis>-octaphenyl-substituted tetrapyrrolic macroheterocyclic cobalt complexes. I. heterogeneous catalysis

The influence of the size of conjugated π-system on catalytic activity of cobalt complex with β-octaphenylporphyrin and its tetraaza-, tetrabenzo and tetrabenzotetraaza derivatives was studied in present work. It is found that catalytic activity for oxidation of sulfur-containing compounds increases under extension of conjugated macrocycle system according to the following series CoP < CoBP ≤ CoPz < CoPPz ? CoPc.     

N(II) oxide coordination to Co complexes with water-soluble porphyrin

Novel, water-soluble metalloporphyrin of zwitterionic type (Co complex with 5,10,15,20-tetra(4N-carboxymethylenepyridyl)porphyrin tetrabromide) was synthesized and its interaction with N(II) oxide was studied. IR and electronic absorption spectra were analyzed. Alcoholic solutions of this complex saturated with NO were found to contain all three types of coordinated ligands, i.e., NO, NO⁺, and NO^?.     

Formation of J-Aggregates of 21-thia-5,10,15,20-tetra-(4-sulfonatophenyl)-porphyrin in Acidified Aqueous Solutions

Journal of Applied Spectroscopy - The formation of Jaggregates of 21-thia-5,10,15,20-(tetra-4-sulfonatophenyl)-porphyrin in acidified aqueous solutions is reported for the first time. The...     

Spectrophotometric Study of Acid-Base Properties of Sulfonated Derivatives of 5,10,15,20-Tetraphenyl-21-thiaand 5,10,15,20-Tetraphenyl-21-oxoporphyrins in the Ethanol–Sulfuric Acid System

Spectral and basic properties of heterosubstituted porphyrins of anionic type have studied by means of spectrophotometric titration in comparison with their structural analog — tetraphenylporphine tetrasulfonic acid. The parameters of electronic absorption spectra and concentration ranges of existence of the mono- and diprotonated forms of the studied ligands as well as the constants of basic dissociation have been determined. Comparative analysis of the effect of the reactive site modification and the medium composition on the basicity of the compounds has been performed.

     

Synthesis and physicochemical properties of girded porphyrins

-Alkyl-substituted 5,15-diphenylporphyrins are synthesized, whose phenyl rings are connected through the ortho positions by bridging groups of various length. The resulting porphyrins were characterized by the electronic absorption and ¹H NMR spectra, and their structure was calculated by the molecular mechanics method. The kinetics of complex formation of the synthesized porphyrins with copper(II) acetate in acetic acid and pyridine depend on the degree of shielding of the reaction center in the tetrapyrrole ligand and its planarity.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1733–1738.Original Russian Text Copyright © 2004 by Kuvshinova, Pukhovskaya, Semeikin, Golubchikov.This revised version was published online in April 2005 with a corrected cover date.     

Spectral,Acid, and Coordination Properties of Dodecasubstituted Porphyrins

Russian Journal of General Chemistry - The results of investigation of the interrelation between the geometric structure and coordination, acid, and spectral properties of a series of porphyrins...     

Physicochemical Basis for the Creation of Liquid-Phase Sensor Materials Based on Tetraaryldithiaporphyrins

Russian Journal of General Chemistry - Basic properties of 5,10,15,20-tetraaryl-21-thia- and 5,10,15,20-tetraaryl-21,23-dithiaporphyrins in acetonitrile were examined spectrophotometrically. The...     

Complexing and Acid-Base Properties of 5,10,15,20-Tetraphenylporphine Oxaderivatives

Russian Journal of General Chemistry - The acid-base properties of 5,10,15,20-tetraphenyl-21-oxaporphyrin and 5,10,15,20-tetraphenyl-21,23-dioxaporphyrin have been studied by means of...