NYU Department of Chemistry crystallographer Chunhua "Tony" Hu teamed up with Wenqian Xu at the Argonne National Laboratory and Qiang Zhu at the University of Nevada Las Vegas to solve a long-standing problem in the crystal structure of glycine dihydrate, an unknown X-phase of glycine. The study, entitled "The Structure of Glycine Dihydrate: Implications for the Crystallization of Glycine from Solution and Its Structure in Outer Space," appears in Angewandte Chemie.
Abstract: Glycine, the simplest amino acid, is also the most polymorphous. Herein, we report the structure determination of an unknown phase of glycine which was firstly reported by Pyne and Suryanarayanan in 2001. To date, the new phase has only been prepared at 208 K as nanocrystals within ice. Through computational crystal structure prediction and powder X-ray diffraction methods, we identified this elusive phase as glycine dihydrate (GDH), representing the first report on a hydrated glycine structure. The structure of GDH has important implications for the state of glycine in aqueous solution, and the mechanisms of glycine crystallization. GDH may also be the form of glycine that comes to Earth from extraterrestrial sources.
This research was supported by the National Science Foundation's MRSEC Program.