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Issue 35, 2011
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Effects of various halogen anions and cations of alkali metals on energetics of excess charge recombination in stilbene donor–acceptor capped DNA hairpins

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Abstract

DNA hairpin conjugates with a stilbenedicarboxamide (Sa) hole donor and a stilbenediether (Sd) hole acceptor are considered as model systems for studying charge recombination (CR) of excess charges in DNA. Using the method of thermodynamic integration, we estimated the relative free energies of this process in hairpins with three adenine:thymine pairs between Sa and Sd surrounded by 1 M aqueous solutions of ionic compounds M+Cl (M = Li, Na, K) and Na+X (X = F, Cl, Br, I). The values of this quantity were calculated with respect to the free energy for the same hairpin in the 1 M NaCl aqueous solution. Based on the results obtained, we conclude that halogen anions have no significant influence on the rate of the CR reaction. By contrast, cations of other alkali metals can considerably change the potential barrier of the process, thus affecting the reaction rate. Different results obtained for cations and anions were attributed to the fundamental distinction in the electrostatic interactions of M+ and X species with negatively charged phosphate groups of the hairpin. In addition, our results show that the relative free energy of CR is larger for cations that are able to be closer to Sd and Sa structural units. The latter correlation suggests that the replacement of Na+ by cations of other alkali metals enables one to change the CR rate modifying it in either direction.

Graphical abstract: Effects of various halogen anions and cations of alkali metals on energetics of excess charge recombination in stilbene donor–acceptor capped DNA hairpins

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Publication details

The article was received on 05 Apr 2011, accepted on 12 Jul 2011 and first published on 05 Aug 2011


Article type: Paper
DOI: 10.1039/C1CP21056D
Phys. Chem. Chem. Phys., 2011,13, 16028-16032

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    Effects of various halogen anions and cations of alkali metals on energetics of excess charge recombination in stilbene donor–acceptor capped DNA hairpins

    A. A. Voityuk, K. Siriwong and Y. A. Berlin, Phys. Chem. Chem. Phys., 2011, 13, 16028
    DOI: 10.1039/C1CP21056D

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