Kinetic Trapping of Metastable Amino Acid Polymorphs
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- 作者：Azhad U. Chowdhury ; Christopher M. Dettmar ; Shane Z. Sullivan ; Shijie Zhang ; Kevin T. Jacobs ; David J. Kissick ; Thora Maltais ; Hartmut G. Hedderich ; Patricia A. Bishop ; Garth J. Simpson
- 刊名：Journal of the American Chemical Society
- 出版年：2014
- 出版时间：February 12, 2014
- 年：2014
- 卷：136
- 期：6
- 页码：2404-2412
- 全文大小：442K
- ISSN：1520-5126
文摘
Second harmonic generation (SHG) microscopy measurements indicate that inkjet-printed racemic solutions of amino acids can produce nanocrystals trapped in metastable polymorph forms upon rapid solvent evaporation. Polymorphism impacts the composition, distribution, and physico-kinetic properties of organic solids, with energetic arguments favoring the most stable polymorph. In this study, unfavored noncentrosymmetric crystal forms were observed by SHG microscopy. Polarization-dependent SHG measurement and synchrotron X-ray microdiffraction analysis of individual printed drops are consistent with formation of homochiral crystal production. Fundamentally, these results provide evidence supporting the ubiquity of Ostwald鈥檚 Rule of Stages, describing the hypothesized transitioning of crystals between metastable polymorphic forms in the early stages of crystal formation. Practically, the presence of homochiral metastable forms has implications on chiral resolution and on solid form preparations relying on rapid solvent evaporation.