Experimental (FT-IR, FT-RS) and theoretical (DFT) studies of vibrational dynamics and molecular structure of 4-n-pentylphenyl-4′-n-heptyloxythiobenzoate (7OS5)

Vibrational spectra of 4-n-pentylphenyl-4′-n-heptyloxythiobenzoate (7OS5) in the solid phase have been measured using Fourier transform infrared (FT-IR) and Raman scattering (FT-RS). Quantum chemical calculations using density functional theory (DFT) with functionals SVWN, B3PW91, MPW1PW91, PBEPBE, and B3LYP at the 6-31+G* basis set level were performed. Calculations using Hartree–Fock (HF) method with the same basis set were also carried out. Finally the complete assignments of the vibrational modes bands were performed on the basis of B3LYP/6-311+G** calculations. Ultimate geometry of molecule was also fixed. The assignments of the bands was based on the potential energy distribution (PED) data using the GAR2PED program. The general agreement between the observed and calculated frequencies are shown.