Efficient deactivation of a model base pair via excited-state hydrogen transfer

Thomas Schultz, Elena Samoylova, Wolfgang Radloff, Ingolf V. Hertel, Andrzej L. Sobolewski, Wolfgang Domcke

Research output: Contribution to journalArticlepeer-review

331 Scopus citations

Abstract

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 ± 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited 1ππ* state and the electronic ground state with a 1ππ* charge-transfer state that is strongly stabilized by the transfer of a proton.

Original languageEnglish
Pages (from-to)1765-1768
Number of pages4
JournalScience
Volume306
Issue number5702
DOIs
StatePublished - 3 Dec 2004

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