Investigation of structural spectroscopic and photophysical properties of 2- (Trifluoromethyl) benzoic acid molecules by experimental and theoretical methods

FT–IR, 1H, 13C and 19F NMR, UV–Vis and fluorescence spectra for 2–(trifloromethyl)benzoic acid (2−TFMBA) were recorded. DFT//B3LYP/6–31++G(d,p) calculations were used to determine optimized molecular geometry, vibrational frequencies, 1H, 13C and 19F GIAO−NMR chemical shifts of 2−TFMBA. The detail assignments of vibrational frequencies were carried out on the basis of potential energy distribution (PED) using VEDA program. TD−DFT/B3LYP/6–31++G(d,p) calculations with the PCM (polarizable continuum model) in ethanol and DMSO solvents based on implicit/explicit model and gas phase in the excited state were employed to investigate UV−Vis absorption and fluorescence emission wavelengths. The UV−Vis and emission spectra were given in ethanol and DMSO solvents, and the major contributions to the electronic transitions were obtained. In addition, the NLO parameters (β, γ and (3)) and frontier molecular orbital energies of 2−TFMBA were calculated using B3LYP/6–31++G(d,p) level. The NLO parameters of 2−TFMBA were compared with that of para–Nitroaniline (pNA) and urea which are typical NLO materials. The refractive index (n) is calculated by using the Lorentz−Lorenz equation to observe polarization behavior of 2−TFMBA in DMSO and ethanol solvents. In order to investigate intramolecular and hydrogen bonding interactions, NBO calculations were also performed by the same level. To sum up, considering the well-known biological role, photochemical properties of 2−TFMBA were discussed.