Effect of hydration on the lowest singlet PiPi* excited-state geometry of guanine: a theoretical study.

Full Abstract

An ab-initio computational study was performed to investigate the effect of explicit hydration on the ground and lowest singlet PiPi* excited-state geometry and on the selected stretching vibrational frequencies corresponding to the different NH sites of the guanine acting as hydrogen-bond donors. The studied systems consisted of guanine interacting with one, three, five, six, and seven water molecules. Ground-state geometries were optimized at the HF level, while excited-state geometries were optimized at the CIS level. The 6-311G(d,p) basis set was used in all calculations. The nature of potential energy surfaces was ascertained via the harmonic vibrational frequency analysis; all structures were found minima at the respective potential energy surfaces. The changes in the geometry and the stretching vibrational frequencies of hydrogen-bond-donating sites of the guanine in the ground and excited state consequent to the hydration are discussed. It was found that the first solvation shell of the guanine can accommodate up to six water molecules. The addition of the another water molecule distorts the hydrogen-bonding network by displacing other neighboring water molecules away from the guanine plane.

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Author information

Author/s: Shukla, M K (MK); Leszczynski, Jerzy (J);

Affiliation: Computational Centre for Molecular Structure and Interactions, Department of Chemistry, Jackson State University, Jackson, MS 39217, USA.

Grants: 3S06 GM 008047 (Agency:NIGMS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.

Journal: The journal of physical chemistry. B (J Phys Chem B), published in United States. (Language: eng)

Reference: 2005-Sep; vol 109 (issue 36) : pp 17333-9

Dates: Created 2006/07/20; Completed 2007/06/26; Revised 2007/12/03;

PMID: 16853213, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Guanine - chemistry
Hydrogen Bonding
Models, Molecular

Models, Molecular
Models, Theoretical
Water - chemistry

Associated Chemicals: Guanine (73-40-5) ; Water (7732-18-5)

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