Document Detail

Photoinduced Formation Mechanism of the Thymine-Thymine (6-4) Adduct.
MedLine Citation:
PMID:  23339629     Owner:  NLM     Status:  Publisher    
The photoinduced mechanism leading to the formation of the thymine-thymine (6-4) photolesion has been studied by using the CASPT2//CASSCF approach over a dinucleotide model in vacuo. Following light absorption, localization of the excitation on a single thymine leads to fast singlet-triplet crossing that populates the triplet 3(nπ*) state of thymine. This state, displaying an elongated C4=O bond, triggers (6-4) dimer formation by reaction with the C5=C6 double bond of the adjacent thymine, followed by a second intersystem crossing which acts as a gate between the excited state of the reactant and the ground state of the photoproduct. The requirement of localized excitation on just one thymine, whose main decay channel (by radiationless repopulation of its ground state) is non-photochemical, can rationalize the experimentally observed low quantum yield of formation for the thymine-thymine (6-4) adduct.
Angelo Giussani; Luis Serrano-Andres; Manuela Merchan; Daniel Roca-Sanjuán; Marco Garavelli
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-23
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  -     ISSN:  1520-5207     ISO Abbreviation:  J Phys Chem B     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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