Ichii Tomoaki, Arikawa Takashi, Omoto Kenichiro, Hosono Nobuhiko, Sato Hiroshi, Kitagawa Susumu, Tanaka Koichiro
Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan.
Commun Chem. 2020 Feb 7;3(1):16. doi: 10.1038/s42004-020-0262-9.
Fundamental understanding of the confinement of water in porous coordination polymers (PCPs) is important not only with respect to their application, such as in gas storage and separation, but also for exploring confinement effects in nanoscale spaces. Here, we report the observation of water in an exotic state in the well-designed hydrophilic nanopores of PCPs. Single-crystal X-ray diffraction finds that nanoconfined water has an ordered structure that is characteristic in ices, but infrared spectroscopy reveals a significant number of broken hydrogen bonds that is characteristic in liquids. We find that their structural properties are quite similar to those of solid-liquid supercritical water predicted in hydrophobic nanospace at extremely high pressure. Our results will open up not only new potential applications of water in an exotic state in PCPs to control chemical reactions, but also experimental systems to clarify the existence of solid-liquid critical points.
深入了解水在多孔配位聚合物（PCP）中的受限情况不仅对于其应用（如气体存储和分离）很重要，而且对于探索纳米级空间中的受限效应也很重要。在此，我们报告了在精心设计的PCP亲水性纳米孔中观察到处于奇异状态的水。单晶X射线衍射发现，纳米受限水具有类似于冰的有序结构，但红外光谱显示存在大量类似于液体的断裂氢键。我们发现它们的结构性质与在极高压力下疏水纳米空间中预测的固液超临界水的结构性质非常相似。我们的结果不仅将为处于奇异状态的水在PCP中用于控制化学反应开辟新的潜在应用，还将为阐明固液临界点的存在提供实验系统。
