Suzuki Yoshiharu
Research Center for Advanced Measurement and Characterization, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
J Chem Phys. 2019 Jun 14;150(22):224508. doi: 10.1063/1.5095649.
Polyamorphic transition in water is expected to occur at low temperatures and high pressures. Recently, the polyamorphic transitions of polyol aqueous solutions were examined under pressure at low temperatures, and the location of their liquid-liquid critical points was estimated experimentally. The addition of polyol solute in water induces the shift of polyamorphic transition pressure toward the lower pressure side. Here, by comparing the polyamorphic transition of various polyol aqueous solutions, especially by comparing those of dilute 1,2-propanediol and dilute 1,3-propanediol aqueous solutions, it is clarified that the OH-groups in the polyol molecule efficiently affect the polyamorphic behavior of solvent water. This suggests that the hydrogen bonding interaction between solvent water and polyol solute relates closely to the polyamorphic behavior of solvent water such as the stabilization of high-density-amorph-like solvent water induced by the presence of polyol solute. In addition, the effect of CH groups in the 1,2-propanediol molecule seems to be opposite to the effect of OH groups. These results have important implications for the understandings of low-temperature phenomena of aqueous solutions, for example, hydration, segregation, phase separation, folding/unfolding of macromolecules, glass forming, and nucleation of crystalline ice Ih.
预计水的多晶型转变会在低温高压下发生。最近，研究了多元醇水溶液在低温压力下的多晶型转变，并通过实验估计了它们液-液临界点的位置。在水中添加多元醇溶质会使多晶型转变压力向较低压力侧移动。在此，通过比较各种多元醇水溶液的多晶型转变，特别是比较稀1,2-丙二醇和稀1,3-丙二醇水溶液的多晶型转变，明确了多元醇分子中的OH基团有效地影响了溶剂水的多晶型行为。这表明溶剂水与多元醇溶质之间的氢键相互作用与溶剂水的多晶型行为密切相关，例如多元醇溶质的存在诱导的高密度无定形样溶剂水的稳定化。此外，1,2-丙二醇分子中CH基团的作用似乎与OH基团的作用相反。这些结果对于理解水溶液的低温现象具有重要意义，例如水合作用、偏析、相分离、大分子的折叠/展开、玻璃形成以及冰晶Ih的成核。
