Variation in the biomolecular interactions of nickel(ii) hydrazone complexes upon tuning the hydrazide fragment

Abstract

Three new bivalent nickel hydrazone complexes have been synthesised from the reactions of [NiCl₂(PPh₃)₂] with H₂L {L = dianion of the hydrazones derived from the condensation of o-hydroxynaphthaldehyde with furoic acid hydrazide (H₂L¹) (1)/thiophene-2-acid hydrazide (H₂L²) (2)/isonicotinic acid hydrazide (H₂L³) (3)} and formulated as [Ni(L¹)(PPh₃)] (4), [Ni(L²)(PPh₃)] (5) and [Ni(L³)(PPh₃)] (6). Structural characterization of these compounds 4–6 were accomplished by using various physico-chemical techniques. Single crystal X-ray diffraction data of complexes 4 and 5 proved their distorted square planar geometry. In order to ascertain the potential of the above synthesised compounds towards biomolecular interactions, additional experiments involving interaction with calf thymus DNA (CT DNA) and bovine serum albumin (BSA) were carried out. All the ligands and corresponding nickel(II) chelates have been screened for their scavenging effect towards O₂⁻, OH and NO radicals. The efficiency of complexes 4–6 to arrest the growth of HeLa, HepG-2 and A431 tumour cell lines has been studied along with the cell viability test against the non-cancerous NIH 3T3 cells under in vitro conditions.