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Barrier-free intermolecular proton transfer in the uracil-glycine complex induced by excess electron attachment |
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| Authors: | M Gutowski I Dabkowska J Rak S Xu JM Nilles D Radisic KH Bowen Jr |
| Institution: | (1) Environmental Molecular Sciences Laboratory, Theory, Modeling & Simulation, Pacific Northwest National Laboratory, Richland, WA 99352, USA, US;(2) Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, PL;(3) Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA, US |
| Abstract: | The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT) from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the standard Watson-Crick pairing scheme. Received 6 April 2002 Published online 13 September 2002 |
| Keywords: | PACS 31 10 +z Theory of electronic structure electronic transitions and chemical binding – 33 80 Eh Autoionization photoionization and photodetachment – 36 40 Wa Charged clusters |
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