title: Fast photoinduced electron transfer through DNA intercalation.
abstract: We report evidence for fast photoinduced electron transfer mediated by the DNA helix that requires metal complexes that are avid intercalators of DNA. Here the donor bis(phenanthroline)(dipyridophenazine)ruthenium(II) [Ru(phen)2dppz2+] and acceptor bis(9,10-phenanthrenequinone diimine)(phenanthroline)rhodium(III) [Rh(phi)2phen3+] intercalate into DNA with Kb > 10(6) M-1. Luminescence quenching experiments in the presence of two different lengths of DNA yield upward-curving Stern-Volmer plots and the loss of luminescence intensity far exceeds the change in emission lifetimes. In the presence of a nonintercalative electron acceptor, Ru(NH3)3+(6), Ru(phen)2dppz2+ luminescence is quenched much less efficiently compared to that found for the intercalative Rh(phi)2phen3+ quencher and follows linear Stern-Volmer kinetics; steady-state and time-resolved Stern-Volmer plots are comparable in scale. These experiments are consistent with a model involving fast long-range electron transfer between intercalators through the DNA helix.
authors.affiliation: Division of Chemistry and Chemical Engineering, Beckman Institute, California Institute of Technology, Pasadena 91125.
authors.forename: C J
authors.initials: CJ
authors.lastname: Murphy
authors.forename: M R
authors.initials: MR
authors.lastname: Arkin
authors.forename: N D
authors.initials: ND
authors.lastname: Ghatlia
authors.forename: S
authors.initials: S
authors.lastname: Bossmann
authors.forename: N J
authors.initials: NJ
authors.lastname: Turro
authors.forename: J K
authors.initials: JK
authors.lastname: Barton
mesh_terms: D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D004735:Energy Transfer; D007364:Intercalating Agents / Q000737:chemistry*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010084:Oxidation-Reduction; D010777:Photochemistry; D012238:Rhodium / Q000737:chemistry
chemical_list: D007364:Intercalating Agents; D009838:Oligodeoxyribonucleotides; D004247:DNA; D012238:Rhodium