L-serine III at 8.0 GPa

The structure of a new high-pressure polymorph of L-serine (form III), C3H7NO3, was solved and refined at 8 GPa by single-crystal X-ray diffraction in a diamond anvil cell in situ. The existence of this form was supposed from Raman spectroscopy [Kolesnik et al. (2005). Dokl. Phys. Chem. 404, 61-64 (in Russian), 169-172 (in English)], but its structure remained unknown. Form III preserves the space group P2(1)2(1)2(1) of the two other forms of L-serine; the conformation of the zwitterion and the intermolecular hydrogen bonding in form III differ from those in forms I and II.