Catecholase-like activity of a mononuclear Cu(ii)-6-(2-nitrostyryl)-5H-pyrrolo[2,3-f][1,10]phenanthroline complex in an aqueous medium

Abstract

A mononuclear Cu(ii) complex, abbreviated as CuCIP (where CIP = (E)-6-(2-nitrostyryl)-5H-pyrrolo[2,3-f][1,10] phenanthroline), was synthesized and characterized by 1H-NMR, IR, UV-visible and fluorescence spectroscopies, HRMS, elemental analysis, cyclic voltammetry, electron spin resonance, and X-ray crystallography. The catechol oxidase-mimicking activity of this complex was monitored using a model substrate, 3,5-di-tert-butyl catechol (DTBC), which is oxidized to form 3,5-di-tert-butylquinone (DTBQ). The reaction was studied in a DMSO-water system in an aerobic environment under ambient conditions. The kinetic parameters were evaluated using Michaelis–Menten and Lineweaver–Burke plots. The formation of DTBQ was monitored by cyclic voltammetric measurements, which follow a semiquinone pathway with the formation of H2O2 as a byproduct, as confirmed by a modified iodometric test using UV-visible spectrophotometry.