Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (07): 1676-1682.doi: 10.3866/PKU.WHXB201205041


A Semiclassical Dynamics Simulation on Charge Transfer and Radiationless Deactivation Excited State of π-Stacked Adenine-Thymine System

ZHANG Wen-Ying, MA Jing, YUAN Shuai, SHU Kun-Xian, DOU Yu-Sheng   

  1. Institute of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China
  • Received:2012-02-24 Revised:2012-05-03 Published:2012-06-07
  • Contact: YUAN Shuai
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073242), Natural Science Foundation of Chongqing, China (cstc2011jjA00009), and Project of the Science Technology Foundation of Chongqing Education Committee, China (KJ120516).


A semiclassical electronic radiation ion dynamics (SERID) simulation was used to study the photophysical deactivation of π-stacked adenine and thymine. A laser was only applied to the thymine molecule during the simulations. The results showed that an (A+T-)* type exciplex was formed between excited thymine and unexcited adenine as a consequence of charge transfer. When the intermolecular distance was less than 0.300 nm, the stacked system was recovered to electronic neutrality by charge recombination because of the orbital delocalization effect. When the torsion angle of the C4'-C5' bond of the adenine molecule reached its maximum, the exciplex decayed to its ground state via an avoided crossing. The deactivation channel of the exciplex was found to be dependent on the intermolecular distance and deformation of the adenine molecule. It was difficult for the adenine molecule to undergo strong twist required for deactivation because of the steric hindrance encountered by the C4' and C5' atoms. Consequently, the lifetime of the A-T exciplex was clearly longer than that of the T-T exciplex.

Key words: DNA base, Stacked effect, Exciplex, Charge transfer, Radiationless deactivation


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