A SAXS-WAXS study of the endothermic transitions in amorphous or supercooled liquid itraconazole

• Published in: Thermochimica acta Vol. 644; no. C; pp. 1 - 5
• Main Authors: Benmore, C.J., Mou, Q., Benmore, K.J., Robinson, D.S., Neuefeind, J., Ilavsky, J., Byrn, S.R., Yarger, J.L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 20.11.2016; Elsevier
• Subjects: MATERIALS SCIENCE
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2016.10.004

•X-ray determination of the structure of itraconazole upon cooling from melt.•Subtle inter-molecular transition found in itraconazole at 90°C.•The formation of polydomain lamellar phase is identified below 74°C. Small and wide angle high energy x-ray scattering experiments were performed upon cooling itraconazole from the melt to investigate the structural origin of the two transitions at ∼74°C and ∼90°C observed in DSC measurements. Slight changes to the main WAXS peak at Q=1.33±0.01Å−1 were observed at 90°C and are found to be inter-molecular in nature, suggesting a liquid to isotropic transition. This finding was supported by complementary wide angle neutron scattering measurements. For temperatures at and below ∼74°C two strong rings appear in the 2D-SAXS pattern at Q=0.24±0.01Å−1 and 0.43±0.01Å−1. The SAXS spectra were further deconvoluted into sharp and broad components. A narrowing of the broad component is associated with only minor changes in the packing arrangements of the itraconazole molecules below ∼90°C, while the appearance of the sharp component below ∼74°C is attributed to the formation of a polydomain lamellar phase.