Determination of conformational and spectroscopic features of ethyl trans-alfa-cyano-3-indole-acrylate compound: An experimental and quantum chemical study

The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and non-linear optical properties of ethyl trans-alfa-cyano-3-indole-acrylate (C14H12N2O2) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000–400 cm−1 and 4000–10 cm−1, respectively. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The 1H, 13C and DEPT NMR spectra were recorded in DMSO solution, and gauge-invariant atomic orbitals (GIAO) method was used to predict the isotropic chemical shifts. The UV–Vis absorption spectra of the compound were recorded in the range of 200–800 nm in various solvents of different polarity (acetone, benzene, chlorobenzene, chloroform, DMSO, ethanol, methanol and toluene). Solvent effects were calculated using TD-DFT and CIS method. To investigate the non-linear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

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► Molecular structure of ethyl trans-alfa-cyano-3-indole-acrylate was investigated.
► Spectroscopic properties of molecule were examined by FT-IR, FT-Raman, NMR and UV techniques.
► The complete assignments are performed on the basis of the total energy distribution (TED).
► NLO properties of ethyl trans-alfa-cyano-3-indole-acrylate were investigated.