title: A vibrational spectroscopy study on 3-aminophenylacetic acid by DFT calculations.
abstract: In this study, in which the group vibrations of 3-aminophenylacetic acid were investigated by electronic structure calculations based on Density Functional Theory (DFT), the possible stable conformers of the molecule were searched through a relaxed "potential energy surface scan" carried out at B3LYP/6-31G(d) level of theory. The corresponding equilibrium geometrical and vibrational spectral data for each of the determined stable conformers and for their possible dimer structures were obtained through "geometry optimisation" and "frequency" calculations carried out at B3LYP/6-31G(d) and B3LYP/6-311G++(d,p) levels of theory. The obtained results confirmed that anharmonic wavenumbers calculated at B3LYP/6-311G++(d,p) level generally quite well agree with the experimental wavenumbers, however, harmonic wavenumbers calculated at both levels of theory need an efficient refinement for a satisfactory agreement with experiment. In particular, the harmonic wavenumbers, IR and Raman intensities refined within Scaled Quantum Mechanical Force Field (SQM FF) methodology constituted the primary data set in the interpretation of the experimental FT-IR, FT-Raman and dispersive Raman spectra of 3-aminophenylacetic acid. By the help of these refined spectral data, the effects of conformation and intermolecular hydrogen bonding on the fundamental bands observed in the experimental spectra could be correctly predicted.
authors: Istanbul University, Faculty of Science, Department of Physics, Vezneciler, 34134 Istanbul, Turkey.
authors: Yasemin
authors: Y
authors: Akkaya
authors: Istanbul University, Faculty of Science, Department of Physics, Vezneciler, 34134 Istanbul, Turkey. Electronic address: kbalci@istanbul.edu.tr.
authors: Kubilay
authors: K
authors: Balci
authors: Istanbul University, Faculty of Science, Department of Physics, Vezneciler, 34134 Istanbul, Turkey.
authors: Yeliz
authors: Y
authors: Goren
authors: Istanbul Kultur University, Department of Physics, Atakoy Yerleskesi, Bakirkoy, 34156 Istanbul, Turkey.
authors: Sevim
authors: S
authors: Akyuz
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D010648:Phenylacetates / Q000737:chemistry*; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D000814:Aniline Compounds; D010648:Phenylacetates; C109911:4-aminophenylacetic acid
keywords: Aminophenylacetic acid; Dual scale factors; Hydrogen bonding; SQM FF methodology; Scaled frequencies; Vibrational spectra