Synthesis, characterization, DNA interaction, and cytotoxicity of novel Pd(II) and Pt(II) complexes

Four complexes [Pd(L)(bipy)Cl].4H(2)O (1), [Pd(L)(phen)Cl].4H(2)O (2), [Pt(L)(bipy)Cl].4H(2)O (3), and [Pt(L)(phen)Cl].4H(2)O (4), where L = quinolinic acid, bipy = 2,2'-bipyridyl, and phen = 1,10-phenanthroline, have been synthesized and characterized using IR, (1)H NMR, elemental analysis, and single-crystal X-ray diffractometry. The binding of the complexes to FS-DNA was investigated by electronic absorption titration and fluorescence spectroscopy. The results indicate that the complexes bind to FS-DNA in an intercalative mode and the intrinsic binding constants K of the title complexes with FS-DNA are about 3.5 x 10(4) M(-1), 3.9 x 10(4) M(-1), 6.1 x 10(4) M(-1), and 1.4 x 10(5) M(-1), respectively. Also, the four complexes bind to DNA with different binding affinities, in descending order: complex 4, complex 3, complex 2, complex 1. Gel electrophoresis assay demonstrated the ability of the Pt(II) complexes to cleave pBR322 plasmid DNA.