The electrocatalytic activity of pyrazolyl-thioimidazolyl borate-based zinc(II) complexes towards the hydrolysis of tris(p-nitrophenyl)phosphate

Abstract

Two zinc(II) compounds of pyrazolyl-thioimidazolyl containing ligands of the types [HB(PzMePh)(TtOMe)2ZnCl] 1 and [HB(PzMePh)(TtOMe)2ZnClO4] 2 were synthesized and characterized as new electrocatalysts for the hydrolysis of the phosphotriester tris(4-nitrophenyl)phosphate (TPP). Their structures were characterized spectroscopically by infrared and 1H-13C NMR spectroscopies as well as elemental analysis and thermal analysis. The zinc atoms adopt distorted tetrahedral geometry with coordination chromophores ZnS2NCl and ZnS2NO for complexes 1 and 2, respectively. The electrochemical behavior of the obtained zinc complexes-modified carbon paste electrode (Zn-CPE) has been studied by cyclic voltammetry. The Zn-CPE shows good electrocatalytic activities toward the hydrolysis of TPP, generates the oxidized p-nitrophenol at the surface of CPE. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of zinc(II) complexes 1 and 2 in a carbon paste electrodes.