Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, 606-8502, Japan.
Institute for Integrated Cell-Material Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto, 606-8501, Japan.
Nat Commun. 2020 Feb 18;11(1):843. doi: 10.1038/s41467-020-14627-z.
Water confined within one-dimensional (1D) hydrophobic nanochannels has attracted significant interest due to its unusual structure and dynamic properties. As a representative system, water-filled carbon nanotubes (CNTs) are generally studied, but direct observation of the crystal structure and proton transport is difficult for CNTs due to their poor crystallinity and high electron conduction. Here, we report the direct observation of a unique water-cluster structure and high proton conduction realized in a metal-organic nanotube, Pt(dach)(bpy)Br·32HO (dach: (1R, 2R)-(-)-1,2-diaminocyclohexane; bpy: 4,4'-bipyridine). In the crystalline state, a hydrogen-bonded ice nanotube composed of water tetramers and octamers is found within the hydrophobic nanochannel. Single-crystal impedance measurements along the channel direction reveal a high proton conduction of 10 Scm. Moreover, fast proton diffusion and continuous liquid-to-solid transition are confirmed using solid-state H-NMR measurements. Our study provides valuable insight into the structural and dynamical properties of confined water within 1D hydrophobic nanochannels.
由于其不寻常的结构和动态特性，一维（1D）疏水性纳米通道中的受限水引起了人们的极大兴趣。作为一个代表性体系，通常研究的是充满水的碳纳米管（CNTs），但由于 CNTs 的结晶度差和电子传导性高，难以直接观察其晶体结构和质子传输。在这里，我们报告了在金属有机纳米管[Pt（dach）（bpy）Br]（SO）·32H2O（dach：（1R，2R）-（-）-1,2-二氨基环己烷；bpy：4,4'-联吡啶）中直接观察到的独特的水簇结构和实现的高质子传导。在结晶状态下，在疏水性纳米通道内发现了由水四聚体和八聚体组成的氢键冰纳米管。沿通道方向的单晶阻抗测量揭示了 10 Scm 的高质子传导率。此外，通过固态 H-NMR 测量证实了快速质子扩散和连续的固-液转变。我们的研究为一维疏水性纳米通道中受限水的结构和动力学特性提供了有价值的见解。
