Computational and matrix-isolation FT-IR study of the tautomeric and vibrational properties of methylated guanines

K. Schoone, G. Maes, L. Adamowicz

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The tautomeric and vibrational characteristics of 1,7-dimethylguanine (17DMG), 7-methylguanine (7MG) and 9-methylguanine (9MG) are studied by a combined experimental matrix-isolation FT-IR and a computational study. The theoretical methods used are the RHF, MP2 and DFT/B3LYP method with the 6-31 +(+) G** basis set. For 17DMG, only the most stable amino-oxo tautomer form can be detected in the FT-IR spectrum. The FT-IR spectra of 7MG and 9MG reveal the presence of two tautomers in the matrix in detectable amounts: the amino-oxo-N1H form and the amino-hydroxy form. The amount of the amino- hydroxy form of 7MG is very small (≃ 1%), while the amino-hydroxy form of 9MG, for which the two rotamers can be distinguished in the spectrum, is as abundant as the amino-oxo form. A comparison of the experimental and calculated IR frequencies demonstrates that the most accurate spectral parameters are predicted by the DFT/B3LYP method, especially when this method is used with a set of different scaling factors.

Original languageEnglish (US)
Pages (from-to)505-509
Number of pages5
JournalJournal of Molecular Structure
Volume480-481
DOIs
StatePublished - May 4 1999

Keywords

  • + ab initio calculations
  • DFT
  • Guanines
  • Matrix-isolation
  • Tautomerism

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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