Design, synthesis, structure and biological evaluation of new palladium(II) hydrazone complexes

Abstract

New palladium(II) complexes {[Pd(L)(PPh3)] (2) and [Pd(L)(AsPh3)] (3)} have been synthesized by using 4-hydoxy benzoic acid (5-chloro-2-hydroxy-benzylidene)-hydrazide (H2L) (1) ligand. The structure of the ligand (H2L) (1), and complexes (2 and 3) were confirmed by using analytical, spectral and single crystal X-ray diffraction techniques. The structure of complexes (2 and 3) revealed a square planar geometry around the Pd ion in which the hydrazone is coordinated through ONO atoms. The interaction of the compounds with calf thymus DNA (CT-DNA) was investigated by absorption, emission titration, electrochemical and viscosity methods, indicating that the ligand and the complexes interacted with CT-DNA through intercalation. The good interaction of the ligand and the Pd(II) complexes with bovine serum albumin (BSA) protein was confirmed by UV–visible and fluorescence spectroscopic studies. The better free radical scavenging ability of Pd(II) complexes was evaluated by in vitro antioxidant assays involving DPPH radical, hydroxyl radical and nitric oxide radical. Furthermore, in vitro cytotoxicity studies of 2 and 3 showed higher activity with lower IC50 values even at low concentrations.