Influence of Nucleic Acids on Spectral Properties of Solutions of Pd(II) and Pt(II) Complexes with Aromatic Ligands

The interaction of nucleic acids (calf thymus DNA and pCY B3 plasmid, yeast RNA) with ethylenediamine Pd(II) and Pt(II) complexes containing aromatic heterocyclic ligands (2,2′-bipyridyl, 1,10-phenanthroline, 2-phenylpyridine, 2-(2′-thienyl)pyridine, 7,8-benzoquinoline, methyl 2-phenyl-4-quinolinecarboxylate, coumarin 6, and Nile red) has been studied using electron absorption spectroscopy and gel electrophoresis. The applicability of electron absorption spectroscopy for establishing the intercalation of organometallic complexes into DNA is demonstrated. Among the complexes under study, only Pd(II) complexes with Nile red and coumarin-6 are capable of intense interaction with RNA. Effective relaxing of supercoiled plasmid DNA, which is revealed by gel electrophoresis, indicates that the same complexes intercalate into DNA more actively than the other ones.