Vibrational spectral investigations and density functional theory study of 4-Formylbenzoic acid

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 114; pp. 502 - 508
• Main Authors: Xavier, T.S., Hubert Joe, I., Palafox, M.A., Kumar, Satendra, Rastogi, V.K.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.10.2013
• Subjects: Benzoates - chemistry; Density functional theory; Formates - chemistry; Hydrogen Bonding; ICT; Models, Molecular; NBO; Quantum Theory; Spectrum Analysis, Raman; Density functional theory; NBO; ICT
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2013.05.081

[Display omitted] •DFT calculations for 4-FBA reproduces experimental vibrational wavenumbers excellently.•Molecular geometry optimization exposes the planarity of 4-FBA molecule.•NBO analysis reveals hyperconjugative interactions and stabilization of molecules.•Shifting in CO stretching wavenumber is due to OH⋯O hydrogen bonding.•Lowering of HOMO–LUMO energy gap indicates the possibility of biological activity. An accurate assignment of the vibrational spectra of 4-Formylbenzoic acid in solid state was carried out. For this purpose density functional calculations (DFT) were performed to clarify wavenumber assignments of the experimentally observed bands for the first time. A scaling of the wavenumbers was carried out to improve the calculated values. Good reproduction of the experimental wavenumbers is obtained and the % error is very small in the majority of cases. The NBO analysis was carried out, and it reveals hyper conjugative interaction, ICT and stabilization of molecules.