Structure and vibrational spectroscopy of the fenbufen–β-cyclodextrin inclusion complex

The structure and host–guest interactions in the inclusion complex (179 atoms) of β-cyclodextrin with fenbufen are studied. Fenbufen, the biphenyl derivative γ-oxo-(1,1′-biphenyl)-4-butanoic acid, is a widespread analgesic and non-steroidal anti-inflammatory drug. Its inclusion complex with β-cyclodextrin improves the oral bioavailability and entails fewer side-effects. Optimized molecular structures, atomic net charges and vibrational spectra have been computed for the host and guest molecules, as well as for the inclusion complex. The functional density theory with the B3LYP/3-21+G method/basis set has been applied. The calculated vibrational frequencies have not been scaled, and the simulated spectra have been compared with those obtained experimentally. The host–guest interactions have been investigated in detail.