Combined Synchrotron XRD/Raman Measurements: In Situ Identification of Polymorphic Transitions during Crystallization Processes

详细信息    查看全文

• 作者：Maria Klimakow ; Jork Leiterer ; Janina Kneipp ; Ernst Rssler ; Ulrich Panne ; Klaus Rademann ; Franziska Emmerling
• 刊名：Langmuir
• 出版年：2010
• 出版时间：July 6, 2010
• 年：2010
• 卷：26
• 期：13
• 页码：11233-11237
• 全文大小：848K
• 年卷期：v.26,no.13(July 6, 2010)
• ISSN：1520-5827

文摘

A combination of two analytical methods, time-resolved X-ray diffraction (XRD) and Raman spectroscopy, is presented as a novel tool for crystallization studies. An acoustic levitator was employed as sample environment. This setup enables the acquisition of XRD and Raman data in situ simultaneously within a 20 s period and hence permits investigation of polymorphic phase transitions during the crystallization process in different solvents (methanol, ethanol, acetone, dichloromethane, acetonitrile). These real time measurements allow the determination of the phase content from the onset of the first crystalline molecular assemblies to the stable system. To evaluate the capability of this approach, the setup was applied to elucidate the crystallization process of the polymorphic compound nifedipine. The results indicate the existence of solvent-dependent transient phases during the crystallization process. The quality of the data allowed the assignment of the lattice constants of the hitherto unknown crystal structure of the β-polymorph.