Copper(I) hydrazone complexes: Synthesis, structure, DNA binding, radical scavenging and computational studies

Potential bidentate hydrazone ligands, HL1 (1) and HL2 (2) prepared by the condensation of benzaldehyde or furfuraldehyde with benzhydrazide upon reaction with [CuCl2(PPh3)2] yielded corresponding mononuclear complexes of the compositions [Cu(L1)(PPh3)2] (3) and [Cu(L2)(PPh3)2] (4). The exact nature of coordination of the hydrazones to the metal ion and the structure of the complexes were confirmed by spectral and single crystal X-ray diffraction studies. Interestingly, the reactions of 1 and 2 with [CuCl2(PPh3)2] resulted in the formation of the first structurally characterized copper(I) hydrazone complexes 3 and 4 along with the previously reported complex [CuCl(PPh3)3] 5 as a minor product in both the reactions. The metal complexes 3 and 4 showed significant binding towards calf thymus DNA (CT-DNA) via groove binding mode with binding constants in the magnitude 104–105 M− 1. In addition, the antioxidant activities of the complexes were also investigated through scavenging effect on DPPH, NO˙ and OH˙ radicals. The density functional theory calculations of complex 4 also supported the structure and stability of the reduced complex.

Graphical abstractThe new complexes of [Cu(L1)(PPh3)2] (3) and [Cu(L2)(PPh3)2] (4) were synthesized, characterized and their theoretical and biological studies were carried out.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► Synthesis of new copper(I) hydrazone complexes. ► Structural characterization involving single crystal XRD. ► DNA binding, antioxidant and DFT studies were carried out.