Abstract
Author(s): T.Ramyaa, S.Gunasekaran, G.R.Ramkumaar
(S)-3-aminomethyl hexonic acid (S3AMH) is a well known antiepileptic drug that controls epileptic seizures. In the present study FTIR and FT- Raman spectra of the drug S3AMH have been recorded for the identification of the functional groups. The structure, geometry optimization, vibrational frequencies and vibrational assignments have been made for the stable conformer of the molecule using semi empirical PM6 method, Abinito Restricted Hartree Fock (RHF), Density Functional theory based on Becke 3-lee-yang-parr (B3LYP) and (B3PW91) functional with standard 6-311++G(d,p) basis set. Detailed investigation of the observed fundamental vibrational frequencies of the molecule and calculated results by PM6, RHF, B3LYP and B3PW91methods indicates that B3PW91 is superior for molecular vibrational problems. The HOMO and LUMO energy level, Natural population analysis and the thermodynamic functions have also been calculated for the title molecule using the PM6, RHF, B3LYP and B3PW91methods. B3PW91 based UV and experimental spectral analysis of the molecule have been performed. The RHF, B3LYP and B3PW91methods based NMR calculation procedure has been used to assign the 1 H NMR and 13C NMR chemical shift of S3AMH
