Molecular structure, vibrational spectroscopic, natural bond orbital analysis, frontier molecular orbital analysis and thermodynamic properties of N-tert-butoxy carbonyl-L-phenylalanine by DFT methods

摘要

The FT-IR and FT-Raman spectra of N-tert-butoxy carbonyl-L-phenylalanine (NTBCLPA) molecule havebeen recorded in the region 4000–400 cm~(−1) and 3500–100 cm~(−1) respectively. Optimized geometricalstructure, harmonic vibrational frequencies, and intensities have been computed by the B3LYPdensity functional levels using ccPVDZ and 6-31+G(d) basis sets. The observed FT-IR and FT-Ramanvibrational frequencies are analyzed. The geometries and normal modes of vibration obtained fromDFT method are in good agreement with the experimental data. The charge transfer occurring inthe molecule between HOMO and LUMO energies, frontier energy gap, the molecular electrostaticpotential (MEP) were calculated and analyzed. The statistical thermodynamic functions (heat capacity,entropy, vibrational partition function and Gibbs energy) were obtained for the range of temperature100–1000 K.