Effect of the chiral discrimination on the vibrational properties of (R)-, (S)- and (R,S)-ibuprofen/methyl-β-cyclodextrin inclusion complexes

The effects of chiral discrimination of ibuprofen (IBP) on the complexation process with methyl--cyclodextrin (Me--CD) were investigated in the solid phase by FTIR-ATR spectroscopy and numerical simulation. The inclusion mechanism was deduced from the temperature-dependent analysis of the vibrational spectra, in the C¼O stretching region, of complexes formed by Me--CD with the two enantiomeric and the racemic forms of IBP. The mechanism turned out to be enthalpy-driven, with IBP enantiomers giving rise to more stable inclusion complexes with respect to the racemate