Tracking DNA excited states by picosecond-time-resolved infrared spectroscopy: Signature band for a charge-transfer excited state in stacked adenine-thymine systems

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Title: Tracking DNA excited states by picosecond-time-resolved infrared spectroscopy: Signature band for a charge-transfer excited state in stacked adenine-thymine systems
Authors: Doorley, Gerard W.Wojdyla, MichalWatson, Graeme W.Quinn, Susan J.et al.
Permanent link: http://hdl.handle.net/10197/11600
Date: 29-Jul-2013
Online since: 2020-09-29T10:04:15Z
Abstract: UV photoexcitation of an adenine-thymine heterodimer (ApT) in D 2O yields a complex transient infrared signature in the 1500-1600 cm-1 spectral region. The spectral dynamics fit well to a biexponential decay assignable to two transient species. The first, a short-lived species with a lifetime of ca. 5 ps, originates from the vibrationally hot electronic ground state of the unstacked form of the dinucleotide. The second species is longer-lived (ca. 75 ps), and its yield correlates to the amount of stacked dinucleotide present in solution. We assign the longer-lived component to a charge-transfer (A•+pT •-) state by comparison with calculated spectra for the adenine radical cation and thymine radical anion. Significantly, the CT feature is also identified in UV-excited [poly(dA-dT)]2. This experimental observation gives a powerful insight into how base-base interactions lead to extended-lifetime electronic excited states of the nucleic acid bases and how a dimeric structure controls the relaxation pathway. © 2013 American Chemical Society.
Funding Details: European Commission
Science Foundation Ireland
Type of material: Journal Article
Publisher: American Chemical Society
Journal: Journal of Physical Chemistry Letters
Volume: 4
Issue: 16
Start page: 2739
End page: 2744
Copyright (published version): 2013 American Chemical Society
Keywords: A-T DNADouble helicesUltrafast deactivationEnergy-transferBase stackingNatrual DNAB-DNAFluorescenceExcitation
DOI: 10.1021/jz401258n
Language: en
Status of Item: Peer reviewed
Appears in Collections:CSCB Research Collection
Chemistry Research Collection

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