Polycations XXII. Ru(bpy)2L2 and Ru(phen)2L2 Systems with Cationic 4,4’-Bipyridine Ligands: Syntheses, Characteristics, and Interactions with DNA

Earlier efforts have been concerned with the association of Ruthenium octahedral complexes with DNA. Since the positively charged ruthenium species has been found to associate with the electron rich major groove of double-stranded DNA, it was proposed the addition of cationic sites on the ligands attached to ruthenium would facilitate such association. Thus, we have synthesized several series of octahedral ruthenium complexes bearing ligands having within themselves cationic sites. These have been investigated in their interaction with calf thymus DNA using fluorescence titration analysis. The introduction of the cationic ligands has been found to exhibit enhanced association of the ruthenium (II) species with the DNA as compared to those without such ligands, in keeping with the original concept. This work leads us to conclude that this line of investigation can lead to useful pharmaceutical agents.