Square planar palladium(II) complexes of bipyridines: synthesis, characterization, and biological studies

A series of square planar mononuclear palladium(II) complexes, [Pd(L-n)(OMe)(2)] (where L-n = 4-(4-chlorophenyl)-6-phenyl-2,2'-bipyridine, 4,6-bis(4-chlorophenyl)-2,2'-bipyridine, 4-(4-bromophenyl) -6-(4-chlorophenyl)-2,2'-bipyridine, and 6-(4-chlorophenyl)-4-p-tolyl-2,2'-bipyridine), have been synthesized and characterized. Interaction of palladium complexes with DNA has been investigated by electronic absorption spectra, viscosity measurements and DNA melting temperature techniques. The metal complex-DNA interaction produced hypochromism and bathochromism, suggesting intercalative binding. Viscosity data support the intercalation mode of binding. Palladium(II) complexes promote cleavage of plasmid pUC19 DNA from the supercoiled form to the open circular form. Antibacterial activities of the complexes have also been evaluated against five pathogenic bacteria. The antimicrobial test results reveal that all compounds have good antibacterial activity against both Gram(-ve) and Gram(+ve) bacterial species compared to the ligands and metal salt.