title: Estimation of the rotamerization constants of different conformations of N-acetylalanine: a theoretical and matrix-isolation FT-IR study.
abstract: The conformational landscape of N-acetylalanine has been investigated by a theoretical and matrix-isolation FT-IR study. Optimizations of N-acetylalanine structures has been conducted at successive higher levels of theory HF/3-21G, DFT(B3LYP)/6-31++G** and MP2/6-31++G**. This resulted in three stable conformations. Among these, one conformation contains an intramolecular H-bond. The vibrational properties of these conformations were calculated and used to identify the conformations in a cryogenic argon matrix. The intensities of some bands assigned to a particular conformation were used to estimate the rotamerization constants K(r12) and K(r13) for the equilibria NAA1 NAA2 and NAA1 NAA3, respectively. The obtained experimental values were in agreement with the theoretical predictions.
authors.affiliation: Department of Chemistry, University of Leuven, Celestijnenlaan 200 F, B-3001 Leuven, Belgium. boeckx@hotmail.com
authors.forename: Bram
authors.initials: B
authors.lastname: Boeckx
authors.forename: Guido
authors.initials: G
authors.lastname: Maes
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D008968:Molecular Conformation; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013816:Thermodynamics; D014732:Vibration
chemical_list: C010530:N-acetylalanine; D000409:Alanine