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

• Oxidomethoxido- and peroxido-vanadium(V) complexes have been isolated and characterized.
• An oxidomethoxidovanadium(V) complex has been grafted in a polymer matrix.
• The peroxidase mimicking property of the supported complex has been described.

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.

Oxidation of pyrogallol to purpurogallin, a peroxidase mimicking property, catalyzed by a polymer-supported oxidomethoxidovanadium(V) complex is described.Figure optionsDownload as PowerPoint slide