FTIR, FT-Raman, FT-NMR, UV–visible and quantum chemical investigations of 2-amino-4-methylbenzothiazole

The FT-IR (4000–400 cm−1) and FT-Raman (4000–100 cm−1) spectral measurements and complete assignments of the observed spectra of 2-amino-4-methylbenzothiazole (2A4MBT) have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound were determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV–visible spectrum of the compound was also recorded and the electronic properties, such as HOMO, LUMO and band gap energies were measured by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of methyl and amino groups on the skeletal modes and on the proton chemical shifts have been investigated.

The FT-IR, FT-Raman, 1H and 13C NMR, UV–visible spectral measurements of 2-amino-4-methylbenzothiazole and complete assignments of the observed spectra have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound are determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities, Raman activities and atomic displacements. The geometric parameters, harmonic vibrational frequencies, chemical shifts and absorption wavelengths were compared with the experimental data of the molecule. The influences of methyl and amino groups on the skeletal modes and proton chemical shifts have been investigated.Figure optionsDownload as PowerPoint slideHighlights
► FTIR and FT-Raman spectra of 2-amino-4-methylbenzothiazole (2A4MBT) were analysed.
► Energy, structural and thermodynamical characteristics of 2A4MBT were determined.
► 1H and 13C NMR spectra were recorded and chemical shifts were calculated by GIAO method.
► UV–visible spectrum was recorded and the electronic properties were measured by TD-DFT approach.
► Effect of methyl and amino groups on the frequencies of benzothiazole ring has been analysed.