Kinetic trapping of metastable amino acid polymorphs.

Autor: Chowdhury AU; Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States., Dettmar CM, Sullivan SZ, Zhang S, Jacobs KT, Kissick DJ, Maltais T, Hedderich HG, Bishop PA, Simpson GJ
Jazyk: angličtina
Zdroj: Journal of the American Chemical Society [J Am Chem Soc] 2014 Feb 12; Vol. 136 (6), pp. 2404-12. Date of Electronic Publication: 2014 Feb 04.
DOI: 10.1021/ja410293p
Abstrakt: 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's 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.
Databáze: MEDLINE