How half sandwich ruthenium compounds interact with DNA while not being hydrolyzed; a comparative study

The cytotoxic compounds [(η6-cym)Ru(pqx)Cl]Cl and [(η6-cym)Ru(bpqx)Cl]Cl, (cym is 1-methyl-4-(1-methylethyl)benzene, pqx is 2-(2′-pyridyl)quinoxaline and pbqx is 2-(2′-pyridyl)benzo[g]quinoxaline), bind to the self-complementary oligonucleotide duplex d(5′-CGCGCG-3′)2 non-coordinatively, preserving their saturated coordination sphere (η6-arene-2N-Cl), causing elongation or disruption of the oligonucleotide Watson-Crick (W-C) hydrogen bonds.209