Vibrational spectroscopic, first-order hyperpolarizability and HOMO, LUMO studies of 4-chloro-2-(trifluoromethyl) aniline based on DFT calculations

The Fourier-transform infrared and FT-Raman spectra of 4-chloro-2-(trifluoromethyl) aniline (4C2TFA) were recorded in the region 4000–400 cm−1 and 3500–50 cm−1 respectively. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 4C2TFA were carried out by density functional theory (DFT/B3LYP) method with 6-311+G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The values of the total dipole moment (μ) and the first order hyperpolarizability (β) of the investigated compound were computed using B3LYP/6-311++G(d,p) calculations. The calculated results also show that 4C2TFA might have microscopic non-linear optical (NLO) behavior with non-zero values. A detailed interpretation of infrared and Raman spectra of 4C2TFA is also reported. The calculated HOMO–LUMO energy gap shows that charge transfer occurs within the molecule.

Figure optionsDownload as PowerPoint slideHighlights
► HOMO and LUMO energy gap explains the eventual charge transfer within the molecule.
► The thermodynamic non-linear optical, first-order hyperpolarizabilities and total dipole moment properties of the compound have been calculated in order to get insight in to the compound.
► The TED calculation regarding the normal modes of vibration provides a strong support for the frequency assignment.
► Complete vibrational analysis of 4C2TFA was performed on the basis of DFT calculations at the B3LYP/6-31+G and B3LYP/6-311++G levels of the theory.