title: Conformational isomerism of pyridoxal. Infrared matrix isolation and theoretical studies.
abstract: A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(2p,2d) study of pyridoxal was performed. The calculations resulted in five stable PLHB conformers stabilized by intramolecular O-H⋯O bonding between phenolic OH and carbonyl C=O groups and another thirteen conformers in which OH or/and aldehyde groups are rotated by 180° around CO or/and CC bonds leading, respectively, to formation of PLO, PLA and PLOA conformers. The analysis of the spectra of the as-deposited matrix indicated that two most stable PLHB1 and PLHB2 conformers with intramolecular hydrogen bond are present in the matrix. The exposure of the PL/Ar matrix to mercury lamp radiation (λ>345 nm) induced conformational change of PLHB isomers to PLOA ones.
authors.affiliation: Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kwiatek
authors.affiliation: Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland. Electronic address: zofia.mielke@chem.uni.wroc.pl.
authors.forename: Zofia
authors.initials: Z
authors.lastname: Mielke
mesh_terms: D004583:Electrons; D007536:Isomerism; D049449:Luminescence; D008958:Models, Molecular; D008968:Molecular Conformation; D011730:Pyridoxal / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014466:Ultraviolet Rays
chemical_list: D011730:Pyridoxal
keywords: Conformational isomerism; DFT calculations; Infrared spectra; Matrix isolation; Pyridoxal