Инд. авторы:	Surovtsev N.V., Adichtchev S.V., Malinovsky V.K., Ogienko A.G., Drebushchak V.A., Manakov A.Y., Ancharov A.I., Yunoshev A.S., Boldyreva E.V.
Заглавие:	Glycine phases formed from frozen aqueous solutions: Revisited
Библ. ссылка:	Surovtsev N.V., Adichtchev S.V., Malinovsky V.K., Ogienko A.G., Drebushchak V.A., Manakov A.Y., Ancharov A.I., Yunoshev A.S., Boldyreva E.V. Glycine phases formed from frozen aqueous solutions: Revisited // Journal of Chemical Physics. - 2012. - Vol.137. - Iss. 6. - Art.065103. - ISSN 0021-9606. - EISSN 1089-7690.
Внешние системы:	DOI: 10.1063/1.4739532; PubMed: 22897314; SCOPUS: 2-s2.0-84865168949;
Реферат:	eng: Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice I h was observed in all the cases. On cooling at the rates of 0.5 Kmin and 5 Kmin, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into β-polymorph of glycine. Quench cooling of glycine solutions (15 ww) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice I h and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine X-phase) at 209-216 K, which at 218-226 K transformed into β-polymorph of glycine. The X-phase was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a 6.648 Å, b 25.867 Å, c 5.610 Å, β 113.12); the formation of X-phase from the glycine glassy phase and its transformation into β-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization. © 2012 American Institute of Physics.
Ключевые слова:	Water; Spectrum Analysis, Raman; Solutions; Phase Transition; Glycine; Freezing; Crystallization; Calorimetry, Differential Scanning; X ray diffraction; solution and solubility; Raman spectrometry; phase transition; freezing; differential scanning calorimetry; crystallization; chemistry; article; water; glycine; X-Ray Diffraction; X ray powder diffraction; X ray diffraction; Solutions; Raman spectroscopy; Raman scattering; Liquid nitrogen; Differential scanning calorimetry; Crystalline materials; Scattering techniques; Quench cooling; Preparation technique; Intermediate phase; Glycine solutions; Glassy phase; Frozen aqueous solutions; Crystalline water; Crystalline phase; Cryogenic temperatures; Amino acids;
Издано:	2012
Физ. характеристика:	065103