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Gas‐Phase Conformational Map of the Amino Acid Isovaline
Author(s) -
Neeman E. M.,
León I.,
Alonso E. R.,
Mata S.,
Alonso J. L.
Publication year - 2020
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.201901201
Subject(s) - conformational isomerism , intramolecular force , chemistry , hydrogen bond , ab initio , rotational spectroscopy , quadrupole , amino acid , ab initio quantum chemistry methods , stereochemistry , computational chemistry , photochemistry , molecule , physics , atomic physics , organic chemistry , biochemistry
Abstract Four conformers of the non‐proteinogenic α‐amino acid isovaline, vaporized by laser ablation, are characterized by Fourier‐transform microwave techniques in a supersonic expansion. The comparison between the experimental rotational and 14 N nuclear quadrupole coupling constants and the ab initio calculated ones provides conclusive evidence for the identification of the conformers. The most stable species is stabilized by an N−H⋅⋅⋅O =C intramolecular hydrogen bond and a cis‐COOH interaction, whereas the higher‐energy conformers exhibit an N⋅⋅⋅H−O intramolecular hydrogen bond and trans‐COOH, as in other aliphatic amino acids. The spectroscopic data herein reported can be used for the astrophysical purpose in a possible detection of isovaline in space.