• anthranilic acid;
  • MP2 method;
  • vibrational spectra;
  • PCM;
  • solvent effects


High-level ab initio methods are used to analyze the electronic structure and vibrational spectra of the anthranilic acid or ortho-aminobenzoic acid (o-Abz), both in gas phase and aqueous solution. The geometries of the stationary points for the two lowest energy conformations (I and II) of o-Abz are optimized at the MP2/6-31++G** and MP2/aug-cc-pVDZ levels of theory. Conformation I is found to be more stable, less polar but more polarizable than conformation II. The same levels of calculation are used to obtain the harmonic vibrational frequencies. Polarizable continuum model method is used later to study the solvent effect on the structure and vibrational spectra of o-Abz. Several electronic, electric, and thermodynamical properties are calculated and compared with the available experimental results and other theoretical calculations. The aqueous solution produces red-shift for most of the vibrational frequencies but increases the intensity of vibrations for all modes of vibration of o-Abz. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010