Palladium Complexes Based on 2-Hydrazinopyridine Ligand: Synthesis, Spectroscopic Studies, DFT Calculations, and Cytotoxicity

Abstract

Three new palladium complexes based on 2-hydrazinopyridine (hzpy) ligand, coupled with oxalate (ox), malonate (ma) and pyrophosphate (pyph) ligands, were prepared; [Pd(hzpy)(ox)], [Pd(hzpy)(ma)] and [Pd(hzpy)(pyph)]. The spectroscopic and thermal studies of the complexes suggested that the complexes were of square planar geometry. The complexes were thermally stable with an overall activation energy of 678, 981, and 633 kJ mol–1 for [Pd(hzpy)(ox)]. [Pd(hzpy)(ma)] and [Pd(hzpy)(pyph)], respectively. Geometric optimization of the three complexes was performed at DFT/B3LYP/SDD level through Gaussian 09. TDDFT and frequency calculations were studied to investigate the electronic and vibrational transitions. The potential in vitro cytotoxic activities of the three complexes was studied. The complexes exhibited a moderate cytotoxic effect against four cancer cell lines; MCF-7 (human breast cancer cell line), HepG-2 (human Hepatocellular carcinoma), PC-3 cells (human prostate carcinoma), and HEP-2 (Larynx carcinoma). The IC50 values of the three complexes exhibited a good performance against PC-3 cell line with low IC50 values reached 2.87 μg/ml for [Pd(hzpy)(ox)] compared to the IC50 of Vinblastine sulfate (42.4 μg/ml).