Publication Date:
2004-12-04
Description:
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 1pipi* state and the electronic ground state with a 1pipi* charge-transfer state that is strongly stabilized by the transfer of a proton.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schultz, Thomas -- Samoylova, Elena -- Radloff, Wolfgang -- Hertel, Ingolf V -- Sobolewski, Andrzej L -- Domcke, Wolfgang -- New York, N.Y. -- Science. 2004 Dec 3;306(5702):1765-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Born Institute Berlin, Max-Born-Strasse 2a, D-10247 Berlin, Germany. schultz@mbi-berlin.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15576616" target="_blank"〉PubMed〈/a〉
Keywords:
Aminopyridines/*chemistry
;
*Base Pairing
;
Chemistry, Physical
;
DNA/*chemistry
;
Dimerization
;
Hydrogen/*chemistry
;
Hydrogen Bonding
;
Mass Spectrometry
;
Models, Chemical
;
Physicochemical Phenomena
;
Protons
;
Thermodynamics
;
Ultraviolet Rays
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
