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Issue 25, 2012
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Photoreaction channels of the guanine–cytosine base pair explored by long-range corrected TDDFT calculations

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Abstract

Photoinduced processes in the Watson–Crick guanine–cytosine base pair are comprehensively studied by means of long-range corrected (LC) TDDFT calculations of potential energy profiles using the LC-BLYP and CAM-B3LYP functionals. The ab initio CC2 method and the conventional TDDFT method with the B3LYP functional are also employed to assess the reliability of the LC-TDDFT method. The present approach allows us to compare the potential energy profiles at the same computational level for excited-state reactions of the base pair, including single and double proton transfer between the bases and nonradiative decay via ring puckering in each base. In particular, long-range correction to the TDDFT method is critical for a qualitatively correct description of the proton transfer reactions. The calculated energy profiles exhibit low barriers for out-of-plane deformation of the guanine moiety in the locally-excited state, which is expected to lead to a conical intersection with the ground state, as well as for single proton transfer from guanine to cytosine with the well-known electron-driven proton transfer mechanism. Thus the present results suggest that both processes can compete in hydrogen-bonded base pairs and play a significant role in the mechanism of photostability.

Graphical abstract: Photoreaction channels of the guanine–cytosine base pair explored by long-range corrected TDDFT calculations

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Publication details

The article was received on 05 Dec 2011, accepted on 17 Apr 2012 and first published on 18 Apr 2012


Article type: Paper
DOI: 10.1039/C2CP23867E
Phys. Chem. Chem. Phys., 2012,14, 8866-8877

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    Photoreaction channels of the guanine–cytosine base pair explored by long-range corrected TDDFT calculations

    S. Yamazaki and T. Taketsugu, Phys. Chem. Chem. Phys., 2012, 14, 8866
    DOI: 10.1039/C2CP23867E

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