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IR Low‐Temperature Matrix and ab Initio Study on β‐Alanine Conformers
Author(s) -
Dobrowolski Jan Cz.,
Jamróz Michał H.,
Kołos Robert,
Rode Joanna E.,
Sadlej Joanna
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800383
Subject(s) - conformational isomerism , ab initio , ab initio quantum chemistry methods , anharmonicity , chemistry , spectral line , infrared spectroscopy , computational chemistry , alanine , matrix isolation , population , argon , molecule , physics , organic chemistry , condensed matter physics , biochemistry , demography , amino acid , sociology , astronomy
For the first time the argon‐matrix low‐temperature FTIR spectra of β‐alanine are recorded. They reveal a quite complicated spectral pattern which suggests the presence of several β‐alanine conformers in the matrix. To interpret the spectra, the eighteen β‐alanine conformers, stable in the gas phase, are estimated at the B3LYP and MP2 levels combined with the aug‐cc‐pVDZ. Ten low‐energy structures are reoptimized at the QCISD/aug‐cc‐pVDZ and B3LYP and MP2 levels by using the aug‐cc‐pVTZ basis sets. Assignment of the experimental spectra is undertaken on the basis of the calculated B3LYP/aug‐cc‐pVDZ anharmonic IR frequencies as well as careful estimation of the conformer population. The presence of at least three β ‐alanine conformers is demonstrated. The detailed analysis of IR spectra points to the possible presence of five additional β ‐alanine conformers.