Synthesis, stability, and electrocatalysis by Cu(II) and Zn(II) complexes of meso-bridged isomeric porphyrinoid tetraphenylporphycene

Abstract

Spectral characteristics (electronic absorption spectra, fluorescence emission spectra, ¹H NMR) of prepared Cu(II) and Zn(II) complexes of 2,7,12,17-tetraphenylporphycene {H₂(β-Ph)₄Por}, their thermal stability, and persistence toward acids, as well as electrochemical and electrocatalytic properties have been discussed. It has been found by cyclic voltammetry that the electrocatalytic activity of metalloporphycenes M(β-Ph)₄Por in the reaction of molecular oxygen reduction is close to that of metalloporphyrins M(ms-Ph)₄P. Thermal stability and persistence of M(β-Ph)₄Por in acidic medium are considerably lower than those of porphyrin analogs. Thus, the kinetic stability of copper(II) complex of 2,7,12,17-tetraphenylporphycene in HOAc–H₂SO₄ medium as compared with Cu(ms-Ph)₄P is lower by more than an order of magnitude, while its thermal stability is almost 200°С lower, which is caused by sterically unfavorable change in the shape of coordination center of ligand H₂(β-Ph)₄Por upon complexation.