Novel ONN pincer type copper(II) hydrazide complexes: An investigation on the effect of electronegativity and ring size of heterocyclic hydrazides towards nucleic acid/protein binding, free radical scavenging and cytotoxicity

Four new, pincer type copper complexes 5–8 were synthesised from the reactions of CuCl2·2H2O with respective hydrazide ligands 1–4 (HL1–HL4) and characterized by various physicochemical techniques. The single crystal XRD and spectral data revealed that all the ligands are monoanionic, tridentate pincer analogues chelating agent, which coordinate via ONN donor atoms to the copper ion. The effect of electronegativity and ring size of heterocyclic hydrazide moiety of ONN pincer type copper(II) chelates on nucleic acid interaction and protein binding was investigated by in vitro experiments. In addition, scavenging activity and cytotoxicity of the newly synthesized complexes of the composition [Cu(L1–4)Cl] were also evaluated.