Yes / Spurred by the enormous interest in co-crystals from the pharmaceutical industry, many novel co-crystals of active pharmaceutical ingredients have been discovered in recent years and this has in turn led to an increasing number of reports on polymorphs of co-crystals. Hence, a thorough characterization and understanding of co-crystal polymorphs is a valuable step during drug development. The purpose of this study is to perform in situ structural analysis and to determine thermodynamic stability of a dimorphic co-crystal system, 1:1 caffeine-glutaric acid (CA-GA, Forms I and II). We performed thermal and structural characterizations by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), hot-stage microscopy (HSM), slurry and in situ variable temperature X-ray diffraction (VTXRD). For completeness, we have also re-determined crystal structures of CA-GA Forms I and II at 180 K using single crystal X-ray diffraction. Our results revealed that Form II is stable and Form I is metastable at ambient conditions. Further, the results suggest that the dimorphs are enantiotropically related and the transition temperature is estimated to be 79 Celcius degrees. / This work was supported by Science and Engineering Research Council of A*STAR (Agency for Science, Technology and Research), Singapore.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/7646 |
| Date | 23 December 2015 |
| Creators | Vangala, Venu R., Chow, P.S., Schreyer, M., Lau, G., Tan, R.B.H. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, Accepted Manuscript |
| Rights | This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Grown and Design, copyright © American Chemical Society after peer-review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.cgd.5b00798. |
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