A Caltech Library Service

Double proton transfer dynamics of model DNA base pairs in the condensed phase

Kwon, Oh-Hoon and Zewail, Ahmed H. (2007) Double proton transfer dynamics of model DNA base pairs in the condensed phase. Proceedings of the National Academy of Sciences of the United States of America, 104 (21). pp. 8703-8708. ISSN 0027-8424. PMCID PMC1885566. doi:10.1073/pnas.0702944104.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The dynamics of excited-state double proton transfer of model DNA base pairs, 7-azaindole dimers, is reported using femtosecond fluorescence spectroscopy. To elucidate the nature of the transfer in the condensed phase, here we examine variation of solvent polarity and viscosity, solute concentration, and isotopic fractionation. The rate of proton transfer is found to be significantly dependent on polarity and on the isotopic composition in the pair. Consistent with a stepwise mechanism, the results support the presence of an ionic intermediate species which forms on the femtosecond time scale and decays to the final tautomeric form on the picosecond time scale. We discuss the results in relation to the molecular motions involved and comment on recent claims of concerted transfer in the condensed phase. The nonconcerted mechanism is in agreement with previous isolated-molecule femtosecond dynamics and is also consistent with the most-recent high-level theoretical study on the same pair.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle Information
Kwon, Oh-Hoon0000-0001-7114-8617
Additional Information:© 2007 by the National Academy of Sciences. Contributed by Ahmed H. Zewail, April 3, 2007 (received for review March 15, 2007). Published online before print May 14, 2007, 10.1073/pnas.0702944104. We thank Dr. H. Paik for his help in the initial setup of the apparatus, and the four reviewers, Profs. Hans-Heinrich Limbach, Richard L. Schowen, Abderrazzak Douhal, and A. Welford Castleman, Jr., for the helpful comments and careful reading of the manuscript. This work was supported by the National Science Foundation. Author contributions: O.-H.K. and A.H.Z. performed research and wrote the paper. The authors declare no conflict of interest. This article contains supporting information online at
Funding AgencyGrant Number
Subject Keywords:7-azaindole; femtochemistry; reaction dynamics; tautomerization
Issue or Number:21
PubMed Central ID:PMC1885566
Record Number:CaltechAUTHORS:KWOpnas07
Persistent URL:
Official Citation:Oh-Hoon Kwon and Ahmed H. Zewail Double proton transfer dynamics of model DNA base pairs in the condensed phase PNAS 2007 104 (21) 8703-8708; published ahead of print May 14, 2007, doi:10.1073/pnas.0702944104
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8791
Deposited By: Tony Diaz
Deposited On:20 Nov 2007
Last Modified:08 Nov 2021 20:53

Repository Staff Only: item control page