中子衍射
甘油
低温保护剂
化学
分子
氢键
液态水
结晶学
分析化学(期刊)
化学物理
热力学
晶体结构
色谱法
有机化学
细胞生物学
物理
低温保存
生物
胚胎
作者
James J. Towey,A. K. Soper,Lorna Dougan
标识
DOI:10.1021/acs.jpcb.6b01185
摘要
The structure of liquid water is defined by its molecular association through hydrogen bonding. Two different structures have been proposed for liquid water at low temperatures: low-density liquid (LDL) and high-density liquid (HDL) water. Here, we demonstrate a platform that can be exploited to experimentally probe the structure of liquid water in equilibrium at temperatures down to 238 K. We make use of a cryoprotectant molecule, glycerol, that, when mixed with water, lowers the freezing temperature of the solution nonmonotonically with glycerol concentration. We use a combination of neutron diffraction measurements and computational modeling to examine the structure of water in glycerol-water liquid mixtures at low temperatures from 285 to 238 K. We confirm that the mixtures are nanosegregated into regions of glycerol-rich and water-rich clusters. We examine the water structure and reveal that, at the temperatures studied here, water forms a low-density water structure that is more tetrahedral than the structure at room temperature. We postulate that nanosegregation allows water to form a low-density structure that is protected by an extensive and encapsulating glycerol interface.
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