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Exploring concerted effects of base pairing and stacking on the excited‐state nature of DNA oligonucleotides by DFT and TD‐DFT studies
Author(s) -
Ai YueJie,
Cui GangLong,
Fang Qiu,
Fang WeiHai,
Luo Yi
Publication year - 2011
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22524
Subject(s) - excited state , stacking , chemistry , oligonucleotide , charge (physics) , pairing , density functional theory , base pair , atomic physics , absorption spectroscopy , molecular physics , chemical physics , physics , computational chemistry , dna , quantum mechanics , biochemistry , superconductivity , organic chemistry
We have taken (dA) 5 , (dT) 5 , and (dA) 5 ·(dT) 5 as model systems to study concerted effects of base pairing and stacking on excited‐state nature of DNA oligonucleotides using density functional theory (DFT) and time dependent DFT methods. The spectroscopic states are determined to be of a partial A → A charge‐transfer nature in the A·T oligonucleotides. The T → T charge‐transfer transitions produce dark states, which are hidden in the energy region of the steady‐state absorption spectra. This is different from the previous assignment that the T → T charge‐transfer transition is responsible for a shoulder at the red side of the first strong absorption band. The A → T charge‐transfer states were predicted to have relatively high energies in the A·T oligonucleotides. The present calculations predict that the T → A charge‐transfer states are not involved in the spectra and excited‐state dynamics of the A·T oligonucleotides. In addition, the influence of base pairing and stacking on the nature of the 1 nπ* and 1 ππ* states are discussed in detail. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011