title: Cyclodextrin-complexation effects on the low-frequency vibrational dynamics of ibuprofen by combined inelastic light and neutron scattering experiments.
abstract: The effect of the inclusion into cyclodextrins (CD) cavity on the low-frequency vibrational dynamics of the anti-inflammatory drug ibuprofen (IBP) is here investigated by using Raman and inelastic neutron scattering (INS) experiments. The differences observed in the frequency regime 0-100 cm(-1) between the vibrational modes of uncomplexed racemic and enantiomeric IBP are discussed on the basis of comparison with the quantum chemical computation results, taking into account the distinct symmetry properties of the molecules involved in the formation of the host-guest complex. Subsequently, the inspection of the same frequency range in the spectra of pure host methyl-β-CD and its IBP-inclusion complexes allows one to identify significant modifications in the vibrational dynamics of the guest molecule after their confinement into CD cavity. The experimental Raman and neutron spectra and the derived Raman coupling function C(R)(ω) show that the complexation process gives rise to a complete amorphization of the drug, as well as to a partial hindering, in the vibrational dynamics of complexes, of the modes between 50 and 150 cm(-1) attributed to CD molecule. The comparison between the Raman and neutron spectra of free and complexed IBP in the energy range of the Boson peak (BP) gives evidence that the dynamics related to this specific vibrational feature is sensitive to complexation phenomena.
authors.affiliation: Department of Physics and Earth Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Crupi
authors.forename: Aldo
authors.initials: A
authors.lastname: Fontana
authors.forename: Marco
authors.initials: M
authors.lastname: Giarola
authors.forename: Graziano
authors.initials: G
authors.lastname: Guella
authors.forename: Domenico
authors.initials: D
authors.lastname: Majolino
authors.forename: Ines
authors.initials: I
authors.lastname: Mancini
authors.forename: Gino
authors.initials: G
authors.lastname: Mariotto
authors.forename: Alessandro
authors.initials: A
authors.lastname: Paciaroni
authors.forename: Barbara
authors.initials: B
authors.lastname: Rossi
authors.forename: Valentina
authors.initials: V
authors.lastname: Venuti
mesh_terms: D003505:Cyclodextrins / Q000737:chemistry*; D007052:Ibuprofen / Q000737:chemistry*; D008958:Models, Molecular; D033363:Neutron Diffraction; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism; D013816:Thermodynamics; D014732:Vibration
chemical_list: D003505:Cyclodextrins; D007052:Ibuprofen