Intercalative binding and photoredox behavior of Cr(phen)2(dppz)]3+ with B-DNA
Barker, K. D.; Benoit, B. R.; Bordelon, J. A.; Davis, R. J.; Delmas, A. S.; Mytykh, O. V.; Petty, J. T.; Wheeler, J. F.; Kane-Maguire, N. Intercalative binding and photoredox behavior of Cr(phen)2(dppz)]3+ with B-DNA. Inorg. Chim. Acta 2001, 322, 74-78.
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Dramatically increased binding to calf thymus B-DNA is reported for the complex Cr(phen)2(dppz)3+ (where dppz is dipyridophenazine) relative to that observed for Cr(phen)33+. UV-Vis absorption, viscosity, and equilibrium dialysis data provide convincing evidence that this enhanced binding by Cr(phen)2(dppz)3+ is associated with intercalation by the dppz ligand. In aqueous buffer solution (pH 7.4), the 2Eg-†’4A2g phosphorescence signal of Cr(phen)2(dppz)3+ centered at 730 nm is quenched in the presence of calf thymus DNA or the mononucleotides deoxyguanosine-5-€²-monophosphate (dGMP) and deoxyadenosine-5-€²-monophosphate (dAMP). Stern-Volmer lifetime plots for calf thymus DNA, dGMP, and dAMP yield bimolecular quenching rate constants of 3.0Ã—107, 2.4Ã—109, and 1.8Ã—107 M-ˆ’1s-ˆ’1, respectively. The study demonstrates that Cr(phen)2(dppz)3+ is a stronger photooxidant than Cr(phen)33+ and Cr(bpy)33+ (and markedly stronger than Ru(phen)2(dppz)2+), and is capable of both guanine and adenine nucleobase oxidation.
Inorganica Chimica Acta