Mono-, trinuclear nickel(II) and copper(II) dioxime complexes: Synthesis, characterization, catecholase and catalase-like activities, DNA cleavage studies

Abstract

The synthesis and molecular structures of six new mono- and trinuclear complexes [M1L2{M2(phen)}2](ClO4)2 [phen = 1,10-phenanthroline, H2L = dioxime ligand, M1, M2 =Ni(II) and Cu(II)] of the ligand, 4-(4-methylphenylamino)biphenylglyoxime are reported. Structural assignments are supported by a combination of FT-IR, elemental analyses, ICP-OES, magnetic susceptibility and molar conductivity studies. Furthermore these complexes were each tested for their ability to catalyze the oxidation of catechol substrates to quinone with dioxygen at 25°C and disproportionation of hydrogen peroxide in the presence of the added base imidazole. The catalytic results indicated that the heterotrinuclear Cu(II)Ni(II)Cu(II) complex (5) shows greater catecholase activity. On the other hand the trinuclear complexes display efficiency in disproportion reactions of hydrogen peroxide producing water and dioxygen in catalase-like activity and homotrinuclear Cu(II) (6) complex is more active towards catalytic decomposition of hydrogen peroxide. The interaction between these compounds with DNA has also been investigated by agarose gel electrophoresis, the trinuclear copper(II) complexes (5, 6) with HO as a cooxidant exhibited the strongest cleaving activity.