Molecular structure and vibrational spectra of γ-oxo [1,1′-biphenyl]-4-butanoic acid (fenbufen) and its interaction with ofloxacin

Density functional theory study on the molecular structure and vibration spectra of fenbufen

This paper examines the comparative performance of different density functional theory (DFT) methods at various basis sets in predicting molecular and vibration spectra of gamma-oxo-[1,1'-biphenyl]-4-butanoic acid (fenbufen). DFT methods including mPW1PW91, HCTH, SVWN, PBEPBE, B3PW91 and B3LYP were investigated. Different basis sets including LANL2DZ, SDD, LANL2MB, CEP-4G, CEP-31G, and CEP-121G were also considered. It is remarkable that the mPW1PW91/LANL2DZ and mPW1PW91/SDD levels are clearly superior to all of the remaining DFT levels in predicting the structure of fenbufen. The calculated results also indicate that SVWN/LANL2DZ level show better performance in the vibration spectra prediction of fenbufen comparing other DFT methods.

Comparison of DFT methods for molecular structure and vibration spectra of ofloxacin calculations

Comparison of the performance of different density functional theory (DFT) methods at various basis sets in predicting molecular and vibration spectra of ofloxacin was reported. The methods employed in this study comprise six functionals, namely, mPW1PW91, HCTH, LSDA, PBEPBE, B3PW91 and B3LYP. Different basis sets including LANL2DZ, SDD, LANL2MB, 6-31g, 6-311g and 3-21g were also examined. Comparison between the calculated and experimental data indicates that the mPW1PW91/6-311g level afford the best quality to predict the structure of ofloxacin. The results also indicate that B3LYP/LANL2DZ level show better performance in the vibration spectra prediction of ofloxacin than other DFT methods.

Theoretical and vibrational studies of 4,5-diphenyl-2-2 oxazole propionic acid (oxaprozin)

The molecular structure, linear and nonlinear optical properties, and electronic properties of 4,5-diphenyl-2-2 oxazole propionic acid (oxaprozin) as a monomer were investigated by using Hartree-Fock (HF) and density functional theory (DFT) calculations that used 6-31G(d,p) basis set. The first-order hyperpolarizability of oxaprozin (OXA) was found to be 1.117 x 10(-30) esu. The structure of oxaprozin dimer with HF/6-31G(d) level caused by the shifts of O-H and CO bands in the vibrational spectra of oxaprozin were also studied. Moreover, these calculated frequencies of oxaprozin dimer were compared with the solid FT-IR and FT-Raman spectra. The theoretical frequencies and infrared intensities were showed a good agreement with experimental data.