Vibrational spectroscopy and density functional theory study of 4-mercaptobenzoic acid

•Most of the fundamentals vibrations agree well with the predicted frequencies.•Hydrogen bond donors and acceptors are predicted.•The vibrational spectra of 4-MBA are studied experimentally and theoretically.

In this paper, 4-mercaptobenzoic acid (4-MBA/pMBA) was designed as a model molecule for theoretical and experimental studies of the molecule structure. Density functional theory (DFT) calculations have been performed to predict the IR and Raman spectra for the molecule. In addition, Fourier transform infrared (FTIR) and Raman spectra of the compound have been obtained experimentally. Based on the modeling results obtained at the B3LYP/6-311++G∗∗ level, all FTIR and Raman bands of the compound obtained experimentally were assigned. Our calculated vibrational frequencies are in good agreement with the experimental vales. The molecular electrostatic potential surface calculation was performed and the result suggested that the 4-MBA had two hydrogen bond donors and three hydrogen bond acceptors. HOMO–LUMO gap was also obtained theoretically at B3LYP/6-311++G∗∗ level.

Graphical abstract4-Mercaptobenzoic acid was designed as a model molecule for theoretical and experimental studies of the molecule structure. Fourier transform infrared (FTIR) and Raman spectra of the compound have been obtained experimentally. Most of the fundamentals vibrations agree well with the predicted frequencies.Figure optionsDownload full-size imageDownload as PowerPoint slide