Weakly antiferromagnetic vanillin and acetate bridged dinuclear Ni(II) compound exhibiting catecholase-like activity and biological properties

Abstract

A dinuclear nickel compound that features vanillin (van) and acetate (OAc) bridging ligands, [Ni sub(2)(Mu-van) sub(2)(Mu-OAc)(NCS) sub(3)(H sub(2)O)].5H sub(2)O 1, was synthesized and characterized using various techniques. Crystal structure analysis revealed a pair of Ni(II) ions bridged by an acetate anion through a Mu sub(2)-Eta sup(1):Eta sup(1) coordination mode. At the same time, vanillin bridges both nickel(II) centers through phenolic oxygen, separating the two Ni ions by a distance of 3.001(7) angstrom. The temperature-dependent magnetism indicates weak antiferromagnetic behaviour in compound 1, following the Curie-Weiss law with Curie constant C = 1.0145 cm sup(3) K mol sup(-1) and Weiss constant Theta = -4.1 K. Compound 1 was evaluated for its ability to mimic the catechol oxidase enzyme using 3,5-di-tert-butylcatechol as a model substrate with a K sub(cat) value of 157.1 x 102 h sup(-1). Furthermore, compound 1 was tested for its cytotoxicity against HepG2 cancer cells and DNA cleavage properties.