Molecular structure, vibrational spectroscopic, first-order hyperpolarizability and HOMO, LUMO studies of 2-aminobenzimidazole

In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and HOMO–LUMO analysis of 2-aminobenzimidazole (2-ABD). The FTIR (400–4000 cm−1) and FT-Raman spectra (50–3500 cm−1) of 2-ABD were recorded. The molecular geometry, harmonic vibrational wavenumbers and bonding features of 2-ABD in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G(d,p) and 6-31G(d) as basis sets. The energy and oscillator strength were calculated by time-dependent density functional theory (TD-DFT) result complements with the experimental findings. The calculated HOMO and LUMO energies showed that charge transfer occurs within the molecule. Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with the observed spectra.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Molecular structure and vibrational spectra of 2-ABD have been studied. ► The energy and oscillator strength were calculated by TD-DFT. ► UV spectra were measured in different solvents and discussed. ► 2-ABD has many pharmacological activities.