Cytotoxic, antibacterial and nucleic acid interaction studies of square planar palladium(II) complexes

A series of substituted N, O-donor bidentate ligands(Ln) and their square planar mononuclear palladium(II) complexes of the type [PdCl2(Ln)] were synthesized and characterized by elemental analysis, conductivity measurement, TGA, FT-IR, 1H NMR, 13C NMR, LC–MS and electronic spectroscopy. Antibacterial activities of the complexes were evaluated against five pathogenic bacteria. The antimicrobial test results reveal that all the compounds have good antibacterial activity against both Gram(+ve) and Gram(−ve) bacterial species compared to ligands and metal salt. Interaction of a palladium complex with DNA was investigated by absorption titration and viscosity measurement. Hypochromism and bathochromism were observed as a result of interaction between palladium(II) complexes with DNA. It suggests an intercalative binding mode. Furthermore, viscosity measurements data support the intercalation mode of binding. The palladium(II) complexes were found to promote cleavage of plasmid pUC19 DNA from the supercoiled form to the open circular form. Cytotoxic activity of complexes was carried out to calculate LC50 values.