The influence of the tertiary butyl group in the ligand frame on the catalytic activities, DNA cleavage ability and cytotoxicity of dinuclear nickel(II) complexes

Abstract

Dinuclear phenoxo-bridged nickel complexes [Ni2(L1)H2O(CH3COO)](1) and [Ni2(L2)H2O(CH3COO)](2) (where L1H3° = 2-(2′-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabutenyl]-3-enyl]-1,3-imidazolidine and L2H3° = 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-1,3-bis[4-(3,5-di-tert-butyl-2-hydroxyphenyl)-3-azabutenyl]-1,3-idazolidine, and H stands for dissociable protons) have been synthesized and characterized by different spectroscopic methods. Molecular structure of 2 was determined by X-ray crystallography. Redox properties of complexes 1 and 2 were investigated by cyclic voltammetric studies. As functional mimic of active site of galactose oxidase enzyme, complexes 1 and 2 were utilized for the oxidation of primary alcohol. Both the complexes exhibited catecholase activity. DNA interaction studies on complexes 1 and 2 were also investigated. Self-activated DNA cleavage activity of complex 2 was observed. The cytotoxicity of the complexes 1 and 2 was measured using a standard MTT assay and IC50 values for of 1 and 2 were found to be 21.92 µM and 20.69 µM on MCF-7 breast cancer cell line respectively.