Numerical Simulation of the Internal Vibrations of NH2 in Amino-Benzoic Acids

Our present work reports the IR spectra of amino substituted Benzoic Acids recorded by FTIR spectrometer and also simulated theoretically. The simulation was performed using GF matrix and AM1, PM3, DFT method. In this work following steps were taken: optimizing the geometry, computing the IR spectra and comparing it with experimental spectra. Assuming C_s point symmetry, vibrational assignments for the observed frequencies have been proposed. The spectra exhibit distinct features originating from low frequency vibrational modes caused by intra-molecular motion.