Synthesis, spectroscopic, cytotoxic, and DNA binding studies of binuclear 2,2′-bipyridine-platinum(II) and -palladium (II) complexes of meso-α,α′-diaminoadipic and meso-α,α′-diaminosuberic acids

Abstract

Four new binuclear complexes of formula [M 2(bipy) 2(BAA)]Cl 2 (where M is Pt(II) or Pd(II), bipy is 2,2′-bipyridine, and BAA is a dianion of meso-α-α′-diaminoadipic acid (DAA) or meso-α, α′-diaminosuberic acid (DSA)) have been synthesized. These complexes have been characterized by chemical analysis and ultraviolet-visible, infrared, and 1H NMR spectroscopy. The mode of binding of ligands in these complexes has been ascertained by infrared and detailed 1H NMR spectroscopy. These complexes are 1:2 electrolyte in conductivity water. They have also been tested against P388 lymphocytic leukemia cells and their target is DNA molecules. [Pt 2(bipy) 2(DSA)]Cl 2, [Pd 2(bipy) 2(DSA)]Cl 2, and [Pd 2(bipy) 2(DAA)]Cl 2 show I.D. 50 values comparable or lower than cis-diamminedichloroplatinum(II) and [Pt(bipy)(Ala)]Cl. In addition, binding studies of [Pt 2(bipy) 2(DSA)]Cl 2 and [Pd 2(bipy) 2(DAA)]Cl 2 to calf thymus DNA have been carried out and the mode of binding seems to be hydrogen bonding, as suggested earlier for analogous mononuclear amino acid-DNA complexes.