Luminescence quenching by DNA-bound viologens: Effect of reactant identity on efficiency and dynamics of electron transfer in DNA

Shana O. Kelley, Guillermo Orellana*, Jacqueline K. Barton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Photoinduced electron transfer from two intercalating photoactive donors, Ru(phen)2dppz2+ and ethidium, to intercalating viologen acceptors of the N,N′-dialkyl-6-(2′-pyridiniumyl)phenanthridinium family has been investigated through steady-state and time-resolved luminescence quenching measurements. Efficient quenching of the emission from these donors bound to DNA is observed at low concentrations of acceptor (1-10 eq.), and in time-resolved emission experiments it is determined that electron transfer occurs on the nanosecond time scale. Furthermore, transient absorption measurements confirm that the quenching is the result of a charge-transfer process; upon photoreaction of intercalated Ru(phen)2dppz2+ with a viologen acceptor, an intermediate with spectral properties resembling the expected charge-separated pair is observed. The quenching yields and kinetics obtained with this quencher are in marked contrast to those observed with these same donors paired with Rh(phi)2bpy3+ as an acceptor. The differing efficiencies of electron transfer for these donor/acceptor pairs bound to DNA as compared to others previously described are discussed qualitatively in terms of the structural and electronic properties of the different reactants.

Original languageEnglish (US)
Pages (from-to)72-79
Number of pages8
JournalJournal of Photochemistry and Photobiology B: Biology
Volume58
Issue number2-3
DOIs
StatePublished - 2000
Externally publishedYes

Keywords

  • DNA
  • Electron transfer
  • Luminescence quenching
  • Viologens

ASJC Scopus subject areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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