Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5821210 | International Journal of Pharmaceutics | 2011 | 8 Pages |
Low- and high-frequency Raman experiments in the 5-200Â cmâ1 and 600-1800Â cmâ1 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 30Â cmâ1, 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.
Graphical abstractDownload high-res image (309KB)Download full-size image