Matrix-isolation infrared and theoretical studies of the glycine conformers

S. G. Stepanian, I. D. Reva, E. D. Radchenko, M. T.S. Rosado, M. L.T.S. Duarte, R. Fausto, L. Adamowicz

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299 Scopus citations

Abstract

The IR spectra of nonionized glycine and its deuterated derivatives isolated in the low-temperature argon matrices have been measured, and for the first time the infrared spectral characteristics of the three most stable conformers have been determined and assigned. Correlated level ab initio and density functional theory (DFT) calculations of IR frequencies and intensities with extended basis sets were performed and their results were employed to separate the bands of the glycine conformers in the experimental spectra and to assist the assignment. The intramolecular interconversion, conformer III → conformer I, which is observed in the matrices at temperatures higher than 13 K, was found to cause a significant decrease of the band intensities of conformer III in the spectra. This phenomenon was used to distinguish the vibrational bands of this conformer from the bands of the other conformers. The reliability of the Møller-Plesset second-order perturbation theory (MP2) method and the DFT method with the three-parameter density functional, Becke3LYP, in the prediction of the IR spectra of the nonionized glycine conformers was examined. We found that the DFT/Becke3LYP method with aug-cc-pVDZ basis set yields vibrational frequencies of the glycine conformers very similar to the MP2 results. Both DFT and MP2 results are in the excellent agreement with the experimental data.

Original languageEnglish (US)
Pages (from-to)1041-1054
Number of pages14
JournalJournal of Physical Chemistry A
Volume102
Issue number6
DOIs
StatePublished - Feb 5 1998

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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    Stepanian, S. G., Reva, I. D., Radchenko, E. D., Rosado, M. T. S., Duarte, M. L. T. S., Fausto, R., & Adamowicz, L. (1998). Matrix-isolation infrared and theoretical studies of the glycine conformers. Journal of Physical Chemistry A, 102(6), 1041-1054. https://doi.org/10.1021/jp973397a