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, [Ni₂(μ-van)₂(μ-OAc)(NCS)₃(H₂O)]·5H₂O 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 μ₂-η¹:η¹ 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) Å. The temperature-dependent magnetism indicates weak antiferromagnetic behaviour in compound 1, following the Curie–Weiss law with Curie constant C = 1.0145 cm³ K mol⁻¹ and Weiss constant θ = −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_cat value of 157.1 × 10² h⁻¹. Furthermore, compound 1 was tested for its cytotoxicity against HepG2 cancer cells and DNA cleavage properties.