Cytosine anions: Ab initio study

Dayle M.A. Smith, Abraham F. Jalbout, Johan Smets, Ludwik Adamowicz

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Abstract

Theoretical ab initio calculations have been performed to determine the stability of covalent and dipole-bound anions of cytosine. The work is related to the recent anion spectroscopy experiments performed on some nucleic acid bases including cytosine by Schiedt et al. [Chem. Phys. 239 (1998) 511], where two anion states attributed to dipole-bound anions of the amino-hydroxy (A-H) and amino-oxo (A-O) tautomers were detected. The present calculations reveal that (i) the A-O isomer and two rotamers of the A-H isomer have sufficient dipole moments to bind σ excess electrons in stationary dipole-bound states. The calculated adiabatic electron affinities are 58, 22, and 6 meV for the A-O cytosine and the two rotamers of the A-H cytosine, respectively. These values are considerably smaller than the two experimentally determined values of 85 ± 8 and 230 ± 8 meV; (ii) our calculations also describe covalent anions of the A-O and A-H tautomers. In both systems, the six-member ring is noticeably distorted from planarity. According to the calculations only, the A-O covalent anion is vertically stable with respect to the electron attachment, and the corresponding vertical electron detachment energy is 102 meV. However, both A-O and A-H cytosine anions are predicted to be unstable with respect to the adiabatic electron detachment. This finding is consistent with the lack of a covalent anion feature in the experimental spectrum. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)45-51
Number of pages7
JournalChemical Physics
Volume260
Issue number1-2
DOIs
StatePublished - Oct 1 2000

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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