Synthesis, characterization and DNA binding studies of two mixed ligand complexes of ruthenium(II)

Two mixed ligand complexes [Ru(bpy)(2)(DMHBT)]Cl-2(1) and [Ru(phen)2(DMHBT)]Cl-2 (2) (where DMHBT is 11,13-dimethyl-13H-4,5,9,11,14-hexaaza-benzo[b]triphenylene-10,12-dione) have been synthesized and characterized by electrospray ionization (ESI) mass, H-1-H-1 correlation spectroscopy (COSY), electronic spectroscopy, fluorescence spectroscopy and cyclic voltammetry. Spectroscopic titration and viscosity changes of calf thymus (CT)-DNA in the presence of incremental amount of complexes I and 2 clearly demonstrate that both these complexes bind intercalatively to DNA, with binding constant 2.87 +/- 0.20 x 10(4)M(-1) and 1.01 +/- 0.20 x 10(5)M(-1) for complexes I and 2, respectively. All the experimental evidences suggest that the ancillary ligand 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) influences the intercalative binding of these complexes to DNA. (c) 2006 Elsevier Inc. All rights reserved.