Experimentaly and theoreticaly investigation of spectroscopic properties of some fluorobenzoic acid derivatives

In this study, the structural, vibrational and electronic transitions of 2, 3-difluorobenzoic acid and 2,4-difluorobenzoic acid compounds were investigated with experimental and theoretical techniques. The FT-IR and FT-Raman spectra of compounds were recorded in the range of 4000-400 cm-1 and 4000-50 cm-1, respectively. The electronic transitions were determined with help of UV spectroscopy and TD-DFT method. The optimized geometrical parameters were determined with help of DFT/B3LYP method and 6-311++G(d,p) basis set. The obtained geometrical parameters were used to calculate the vibrational and electronic transitions. The theoreticallay computed IR and Raman spectra were compared with experimental ones. The assignments of vibrations were determined using SQM (scaled quantum mechanics) method based on total energy distribution (TED). Besides the experimental UV analysis, the absorption wavelengths were calculated; in addition, the excitation enerjies, HOMO-LUMO enerjies and dipol moment of studied molecules were predicted.