title: Raman spectroscopy of racemic ibuprofen: evidence of molecular disorder in phase II.
abstract: Low- and high-frequency Raman experiments in the 5-200 cm(-1) and 600-1800 cm(-1) ranges were carried out in the crystalline and amorphous states of ibuprofen. Low-frequency investigations indubitably reveal the existence of a molecular disorder in the metastable phase (phase II), through the observation of quasielastic contribution below 30 cm(-1), and the absence of phonon peaks in the Raman susceptibility which mimics the density of vibrational states of an amorphous state. High-frequency Raman spectra indicate a local order in phase II similar to that in the glassy state. Both dynamic and static molecular disorder could contribute to the Raman signatures of the disorder in crystalline phase II. Raman investigations suggest that phase II can be considered as a transient metastable state in the devitrification process of ibuprofen upon heating from a far from equilibrium state toward the stable phase I.
authors.affiliation: Univ Lille Nord de France, F-59000 Lille, France USTL, UMR 8207, F-59650 Villeneuve d'Ascq, France. alain.hedoux@univ-lille1.fr
authors.forename: Alain
authors.initials: A
authors.lastname: Hédoux
authors.forename: Yannick
authors.initials: Y
authors.lastname: Guinet
authors.forename: Patrick
authors.initials: P
authors.lastname: Derollez
authors.forename: Emeline
authors.initials: E
authors.lastname: Dudognon
authors.forename: Natalia T
authors.initials: NT
authors.lastname: Correia
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D003460:Crystallization; D007052:Ibuprofen / Q000737:chemistry*; D015394:Molecular Structure; D013059:Spectrum Analysis, Raman
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007052:Ibuprofen