Ami Takahiro, Oka Kouki, Kitajima Showa, Tohnai Norimitsu
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan.
Angew Chem Int Ed Engl. 2024 Sep 9;63(37):e202407484. doi: 10.1002/anie.202407484. Epub 2024 Aug 4.
Water in hydrophobic nanospaces shows specific dynamic properties different from bulk water. The investigation of these properties is important in various research fields, including materials science, chemistry, and biology. The elucidation of the correlation between properties of water and hydrophobic nanospaces requires nanospaces covered only with simple hydrophobic group (e.g., fluorine) without impurities such as metals. This work successfully fabricated all-organic diamondoid porous organic salts (d-POSs) with highly fluorinated nanospaces, wherein hydrophobic fluorine atoms are densely exposed on the void surfaces, by combining fluorine substituted triphenylmethylamine (TPMA) derivatives with tetrahedral tetrasulfonic acid. This d-POSs with a highly fluorinated nanospace significantly improved their water stability, retaining their crystal structure even when immersed in water over one week. Moreover, this highly hydrophobic and fluorinated nanospace adsorbs 160 mL(STP)/g of water vapor at P/P=0.90; this is the first hydrophobic nanospace, which water molecules can enter, in an all-organic porous material. Furthermore, this highly fluorinated nanospace exhibits very high proton conductivity (1.34×10 S/cm) at 90 °C and 95 % RH. POSs with tailorable nanospaces may significantly advance the elucidation of the properties of specific "water" in pure hydrophobic environments.
疏水性纳米空间中的水表现出与 bulk 水不同的特定动力学性质。对这些性质的研究在包括材料科学、化学和生物学在内的各种研究领域中都很重要。阐明水的性质与疏水性纳米空间之间的相关性需要仅覆盖有简单疏水基团（如氟）且无金属等杂质的纳米空间。通过将氟取代的三苯基甲胺（TPMA）衍生物与四面体四磺酸相结合，这项工作成功制备了具有高度氟化纳米空间的全有机类金刚石多孔有机盐（d-POSs），其中疏水性氟原子密集地暴露在孔隙表面。这种具有高度氟化纳米空间的 d-POSs 显著提高了其水稳定性，即使在水中浸泡一周以上仍能保持其晶体结构。此外，这种高度疏水且氟化的纳米空间在 P/P = 0.90 时吸附 160 mL(STP)/g 的水蒸气；这是全有机多孔材料中首个水分子能够进入的疏水性纳米空间。此外，这种高度氟化的纳米空间在 90 °C 和 95% RH 下表现出非常高的质子传导率（1.34×10 S/cm）。具有可定制纳米空间的 POSs 可能会显著推进对纯疏水环境中特定“水”性质的阐明。
