Electrochemical Properties of Tetrasubstituted Cobalt Phthalocyanines with Fragments of Benzoic Acid

Abstract

The method of cyclic voltammetry is used for the first time to study the electrochemical behavior of cobalt phthalocyanine derivatives with fragments of benzoic acid CoPc(4-O–C₆H₄COOH)₄ and CoPc(4- S–C₆H₄COOH)₄ in an aqueous alkaline solution. Comparative analysis is carried out of the electrochemical behavior and change in the electrocatalytic activity of metal phthalocyanines in the reaction of molecular oxygen electroreduction depending on the functional substitution in the macrocycle molecule. In the case of the CoPc(4-O–C₆H₄COOH)₄ and CoPc(4-S–C₆H₄COOH)₄ compounds, central metal ion oxidation (Co²⁺ → Co³⁺) and reduction (Co²⁺→ Co¹⁺) processes and also two successive one–electron stages of phthalocyanine ligand electroreduction are registered. It is shown that the studied cobalt phthalocyanine derivatives manifest electrocatalytic activity in the process of molecular oxygen electroreduction.