Molecular structure, spectroscopic (FT-IR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO and LUMO analysis of 4′-methylbiphenyl-2-carbonitrile

Abstract

In the present study, the molecular structure, vibrational and electronic transition, isotropic chemical shifts analysis of 4′-methylbiphenyl-2-carbonitrile were presented using experimental techniques (FT-IR, FT-Raman, NMR and UV) and quantum chemical calculations. FT-IR and FT-Raman spectra in solid state were observed in the region 4000–400 cm −1 and 3500–50 cm −1, respectively. The ultraviolet absorption spectrum of studied compound that dissolved in ethanol was examined in the range of 200–400 nm. The 1H and 13C NMR spectra were recorded in DMSO solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The molecular structure and spectroscopic data of the molecule in the ground state were computed by density functional theory (DFT) using 6-31++G(d,p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED) of the vibrational modes, computed with scaled quantum mechanics (SQM) method. 13C and 1H isotropic chemical shifts were computed using the gauge-invariant atomic orbital (GIAO) method. Moreover, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, absorption wavelength were performed by time-dependent DFT approach. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT method produces good results.