ELECTROCHEMICAL BEHAVIOR AND ACTIVITY OF MESO - TETRAKIS(1`-METHYL-PYRID-4- AND 3-YL)PORPHIN SALTS AND COBALT COMPLEXES

In this work 5,10,15,20-tetrakis(1`-methyl-pyrid-4- and -3-yl)porphin tetratosylates and tetraiodide [H2(1`-methyl-Py-4- and -3)4P]4+ (Х-)4, 5,10,15,20-tetrakis(1’-methyl-pyrid-4- and -3-yl)porphin tetratosylates cobalt [Сo-tetrakis(1`-methyl-Py-4- and -3)4P]4+ (Ts-)4 have been synthesized and characterized. These compounds were differed by the isomerism of the meso-substituent of the porphyrin molecule and the nature of the counterion (Ts-, I-). The data of the redox-behavior and efficiency of the use of porphyrin compounds in oxygen reduction reaction (ORR) have been obtained. The electrochemical behavior has been studied by using the cycling voltammetry method. It should be noted that two stages of the electroreduction process were observed in an argon medium for ligands. For the cobalt complexes additional processes was found. The process of the porphyrin macrocycle electroreduction in the potential region of -0.78 ... -1.36 V and the Co3+↔Co2+, oxidation (reduction) process localized on the metal atom at Еred/ox= 0.19 V were found. The N-substitution of the pyridyl fragment of porphyrins leads to a small increase in their reducing ability, in comparison with unsubstituted tetrapyridylporphyrins [H2(Py-4- and -3)4P]. The possibility of using water-soluble porphyrins in the ORR electrocatalysis has been considered. It has been shown that the nature of the metal cation has a significant effect on the electrocatalytic activity of compounds in the molecular oxygen ionization reaction of in an aqueous-alkaline media. The activity of Сo-complexes was increased by ~ 50-90 mV compared with ligands and a system without a catalyst at ~ 140-160 mV. For citation: Berezina N.M., Bazanov M.I., Berezina G.R., Lubimova T.V., Semeikin A.S. Electrochemical behavior and activity of meso - tetrakis (1`-methyl-pyrid-4- and 3-yl)porphin salts and cobalt complexes. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 2. P. 62-69. DOI: 10.6060/ivkkt.20256802.7129.