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A high‐pressure single‐crystal to single‐crystal phase transition in DL‐alaninium semi‐oxalate monohydrate with switching‐over hydrogen bonds
Author(s) -
Zakharov Boris A.,
Boldyreva Elena V.
Publication year - 2013
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
eISSN - 2052-5206
pISSN - 2052-5192
DOI - 10.1107/s2052519213011676
Subject(s) - phase transition , hydrogen bond , crystallography , raman spectroscopy , ambient pressure , crystal structure , single crystal , materials science , hydrate , crystal (programming language) , chemistry , diamond anvil cell , oxalate , diffraction , inorganic chemistry , thermodynamics , molecule , organic chemistry , optics , programming language , physics , computer science
A single‐crystal to single‐crystal transition in DL‐alaninium semi‐oxalate monohydrate at a pressure between 1.5 and 2.4 GPa was studied by single‐crystal X‐ray diffraction and Raman spectroscopy. This is the first example of a single‐crystal diffraction study of a high‐pressure phase transition in a crystalline amino acid salt hydrate. Selected hydrogen bonds switch over and become bifurcated, whereas the others are compressed continuously. The transition is accompanied by pronounced discontinuities in the cell parameters and volume versus pressure, although no radical changes in the molecular packing are induced. Although, in contrast to DL‐alanine, in the crystal structure of the salt there are short O—H...O hydrogen bonds, the structure of the salt is more compressible. At the same time, the structure of DL‐alanine does not undergo pressure‐induced phase transitions, whereas the structure of DL‐alaninium semi‐oxalate monohydrate does, and at a relatively low pressure. The anisotropy of lattice strain for the low‐pressure phase differs from that on cooling at ambient pressure; interestingly, the anisotropy of the pressure‐induced compression of the high‐pressure phase is quite similar to the lattice strain of the low‐pressure phase on cooling.