Acta Cryst. (2006). B62, 815-825 [ doi:10.1107/S010876810601799X ]
Abstract: The hydrostatic compression of L-serine-d7 has been studied to 8.1 GPa by neutron powder diffraction. Over the course of this pressure range the compound undergoes two phase transitions, the first between 4.6 and 5.2 GPa, yielding L-serine-II, and the second between 7.3 and 8.1 GPa, yielding L-serine-III. All three polymorphs are orthorhombic, P212121, and feature chains of serine molecules connected via head-to-tail ND
O hydrogen bonds formed between ammonium and carboxylate groups. The chains are linked into a ribbon by a second set of NDO hydrogen bonds. The hydroxyl moieties are distributed along the outer edges of the ribbon and in phase I they connect the ribbons into a layer by chains of ODOD hydrogen bonds. The layers are connected together by a third set of NDO hydrogen bonds, forming 
rings with substantial voids at their centres. In the transition from phase I to II these voids begin to close up, but at the cost of breaking the ODOD chains. The ODOD hydrogen bonds are replaced by shorter ODO hydrogen bonds to carboxylate groups. At 7.3 GPa the OO distance in the ODO hydrogen bonds measures only 2.516 (17) Å, which is short, and we propose that the phase transition to phase III that occurs between 7.3 and 8.1 GPa relieves the strain that has built up in this region of the structure. The hydroxyl D atom now bifurcates between the ODO contact that had been present in phase II and a new ODO contact formed to a carboxylate in another layer. Hirshfeld surface fingerprint plots show that DD interactions become more numerous, while hydrogen bonds actually begin to lengthen in the transition from phase II to III.
Keywords: neutron powder diffraction; hydrostatic compression; hydrogen bonding.
 |   Rietveld powder data file (CIF format) (89.1 kbytes) |
| Rietveld powder data file (CIF format) (87.2 kbytes) |
| Rietveld powder data file (CIF format) (89.0 kbytes) |
| Rietveld powder data file (CIF format) (89.0 kbytes) |
To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.
The download button will force most browsers to prompt for a file name to store the data on your hard disk.
Where possible, images are represented by thumbnails.
Copyright © International Union of Crystallography
IUCr Webmaster