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

The Fourier transform Raman and Fourier transform infrared spectra of fenbufen (γ-oxo [1,1′-biphenyl]-4-butanoic acid) were recorded in the solid phase. The gas-phase structure and conformational properties of fenbufen were determined by quantum-chemical calculations (HF and DFT/B3LYP with 6-311++G(d,p) basis set). The harmonic wave numbers were calculated by the density functional theory (DFT) calculations with B3LYP functional and 6-311++G(d,p) basis set, and the scaled values were in good agreement with the majority of the experimental observations. A complete assignment of the fundamentals was proposed based on the total energy distribution (TED) calculation. The possible interaction between fenbufen and ofloxacin which is a synthetic antimicrobial agent was investigated. The changes observed in some bands of mixed drug indicated that there is an interaction between the two drug molecules.