Electrochemical and Photophysical Properties of DNA Metallo-intercalators Containing the Ruthenium(II) Tris(1-pyrazolyl)methane Unit

Three new ruthenium(II) complexes containing the tris(1-pyrazolyl)methane (tpm) ligand have been prepared:  [Ru(tpm)(L)(dppn)]n+ (where n = 1; L = Cl (5), n = 2; L = MeCN (6) and pyridine (7); dppn = benzo[i]dipyrido[3,2-a:2‘,3‘-c]phenazine). Complex 6 was structurally characterized by single-crystal X-ray diffraction. Binding
parameters of these complexes with calf thymus DNA are reported and compared to those obtained for a previously
reported monocation, [RuCl(tpm)(dppz)]+. Binding studies with the dications and the synthetic oligonucleotides poly(dA)·poly(dT) and poly(dG)·poly(dC) have also been determined. Photophysical and electrochemical properties of
5−7 have been investigated and compared with their dipyridophenazine (dppz) analogues.