Experimental and DFT studies on the vibrational and electronic spectra of 9-p-tolyl-9H-carbazole-3-carbaldehyde

• The FT-IR, FT-Raman spectra and UV–Vis of the title compound have been recorded experimentally.
• Optimized geometry, vibrational frequencies, IR and Raman intensities are obtained with RHF and six DFT methods.
• The absorption spectra of the compound were computed both in gas-phase and in DMF solution.
• The hybridization and covalent effects in polyatomic wave functions has been studied by analysis the NBO.

The compound 9-p-tolyl-9H-carbazole-3-carbaldehyde (HCCD) was synthesized and characterized by X-ray diffraction, FT-IR, FT-Raman and UV–Vis spectra. The X-ray diffraction study showed that HCCD has a Z-configuration. The benzene ring including methyl is twisted from the mean plane of the carbazole group by 59.7(3)°, which is comparable with the calculated result 65° for B3LYP/6-311++G(d, p) method. Vibrational spectra and electronic spectra measurements were made for the compound. Optimized geometrical structure and harmonic vibrational frequencies were computed with B-based DFT (BLYP, B3LYP and cam-B3LYP) methods, and WB-based DFT (WB97, WB97X and WB97XD) methods and ab initio RHF method using 6-311++G(d, p) basis set. Assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in DMF solution using TD-(cam)B3LYP/6-311++G(d, p) and PCM-(cam)B3LYP/6-311++G(d, p) approaches, respectively. The calculated results provide good descriptions of the bands maxima in the observed electronic spectrum. Temperature dependence of thermodynamic parameters in the range of 100–1000 K was determined. The natural atomic hybrids were calculated and discussed.

DFT study of the structural and spectroscopic properties of HCCD has been reported.Figure optionsDownload as PowerPoint slide