Vibrational spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations and computational study of 5-nitro-2-(4-nitrobenzyl) benzoxazole

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The energy and oscillator strength calculated by time dependent density functional theory almost compliments with experimental findings. Gauge-including atomic orbital 1H NMR chemical shifts calculations were carried out by using B3LYP functional with 6-31G* basis set. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization have been analyzed using NBO analysis. MEP was performed by the DFT method and the predicted infrared intensities and Raman activities have also been reported. The calculated geometrical parameters are in agreement with that of similar derivatives.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► IR, Raman spectra and NBO analysis were reported. ► The wavenumbers are calculated theoretically using Gaussian09 software. ► The wavenumbers are assigned using PED analysis. ► The geometrical parameters are in agreement with that of similar derivatives.