Synthesis, characterization, interaction with DNA and cytotoxicity of Pd(ii) and Pt(ii) complexes containing pyridine carboxylic acid ligands

Abstract

Four metal complexes [Pd(L₁)Cl₂·2H₂O] (1), [Pt(L₁)Cl₂·2H₂O] (2), [Pd(L₂)Cl₂·H₂O] (3) and [Pt(L₂)Cl₂·H₂O] (4) (L₁ = 2,2′-bipyridyl-5,5′-dicarboxylic acid, L₂ = 2,2′-bipyridyl-4,4′-dicarboxylic acid) have been synthesized under hydrothermal conditions and fully characterized by IR and ¹H-NMR spectra, elemental analysis, and X-ray single crystal diffraction analysis. Interactions of these complexes with fish sperm DNA (FS-DNA) were investigated using UV-Vis absorption and fluorescence spectroscopic methods. Further insight was brought by quantum chemistry calculations by means of G03 package and taking B3LYP functional Lanl2dz Gen basis set. Agarose gel electrophoresis run on pBR322 plasmid DNA gave proof that all four complexes exhibit efficient DNA cleavage. Complexes 1–4 manifested cytotoxic specificity and a significant cancer cell inhibitory rate. Independent apoptosis tests under the light microscope, performed on hematoxylin–eosin stained HeLa cells, evidenced morphological changes induced by all the complexes.