A polymer grafted oxidomethoxidovanadium(V) complex of an ONO donor ligand mimicking peroxidase activity

Abstract

The reaction between [VIVO(acac)2] and the ONO donor tridentate ligand H2hap-iah (I) [H2hap-iah = Schiff base obtained by the condensation of equimolar amounts of o-hydroxyacetophenone (hap) and indole-3-acetic hydrazide (iah)] in an equimolar ratio under an oxygen atmosphere in refluxing methanol gives [VVO(OMe)(hap-iah)] (1). Treatment of 1 in methanol with H2O2 in the presence of KOH results in the formation of K[VVO(O2)(hap-iah)] (2). Complex 1 has been grafted into chloromethylated polystyrene cross-linked with 5% divinylbenzene {now abbreviated as PS-[VVO(OMe)(hap-iah)] (3)} via covalent bonding through the imino nitrogen atom of the indole group. The two complexes have been characterized by various spectroscopic techniques (IR, electronic, 1H, 13C and 51V NMR, ESI-MS), analytical and thermal studies. The polymer-grafted complex 3 has also been analyzed by field-emission scanning electron micrographs (FE-SEM) as well as energy dispersive X-ray (EDAX) studies. The polymer-grafted complex 3 has been used as a catalyst for the peroxidase-like oxidation of pyrogallol to purpurogallin in pH 7 buffer solution. Its high peroxidase mimicking ability, easy separation from the reaction medium and the reusability, without any considerable decrease in activity, suggest the practical utility of the catalyst. © 2015 Elsevier Ltd. All rights reserved.