Understanding the Solid-State Hydration Behavior of a Common Amino Acid: Identification, Structural Characterization, and Hydration/Dehydration Processes of New Hydrate Phases of l-Lysine

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• 作者：P. Andrew Williams ; Colan E. Hughes ; Jean Martin ; Emilie Courvoisier ; Asma B. M. Buanz ; Simon Gaisford ; Kenneth D. M. Harris
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：120
• 期：17
• 页码：9385-9392
• 全文大小：465K
• 年卷期：0
• ISSN：1932-7455

文摘

The crystal structure of l-lysine was reported very recently and represented the final member of the set of 20 directly encoded proteinogenic amino acids to have a crystal structure of the enantiomerically pure form determined. Under ambient conditions, l-lysine has a strong propensity to undergo hydration by incorporation of water into the crystal structure, and dehydration under rigorously dry conditions is required to obtain anhydrous l-lysine. In the present paper, we explore the hydration of l-lysine, which has led to the identification and characterization of a hemihydrate phase and a monohydrate phase. As the hydration processes give rise to microcrystalline powder samples of the hydrate phases, powder X-ray diffraction has been exploited for crystal structure determination of both l-lysine hemihydrate and l-lysine monohydrate. The conditions for interconversion between anhydrous l-lysine and the two hydrate phases have been investigated by dynamic vapor sorption measurements, leading to an understanding of the hydration/dehydration behavior in this system.