MP2, DFT and ab initio calculations on thioxanthone

Density functional theory (DFT), HF and MP2 calculations have been carried out to investigate thioxanthone molecule using the standard 6-31+G(d,p) basis set. The results of MP2 calculations show a butterfly structure for thioxanthone. The calculated results show that the predicted geometry can well reproduce the structural parameters. The predicted vibrational frequencies were assigned and compared with experimental IR spectra. A good harmony between theory and experiment is found. The theoretical electronic absorption spectra have been calculated using CIS method. 13C and 1H NMR of the title compound have been calculated by means of B3LYP density functional method with 6-31+G(d,p) basis set. The comparison of the experimental and the theoretical results indicate that density functional B3LYP method is able to provide satisfactory results for predicting NMR properties.

Graphical abstractDensity functional theory (DFT), HF and MP2 calculations have been carried out to investigated thioxanthone molecule using the standard 6-31+G(d,p) basis set. The theoretical electronic absorption spectra have been calculated using CIS method. 13C and 1H NMR of the title compound have been calculated by means of B3LYP density functional method with 6-31+G(d,p) basis set. Interestingly application of MP2 method causes a butterfly shape for titled compound. The HF and DFT methods calculate a planar structure for thioxanthone molecule but MP2 method predicts a non-planer structure.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Molecular structure, geometric parameters, vibrational spectra and NBO analysis of thioxanthone were calculated and reported. ► The spectral data such as IR, NMR and UV calculated and compared with experimental data. Harmonic and anharmonic frequencies were carried out by DFT method. ► Experimental data shows good agreement with theoretical data. ► The charges on important nucleus calculated and reported. ► Thioxanthone derivatives have more biological activities such as anticancer.