Flexible metal–organic materials (FMOMs) with stepped isotherms can offer enhanced working capacity in storage applications such as adsorbed natural gas (ANG) storage. Unfortunately, whereas >1000 FMOMs are known, only a handful exhibit methane uptake of >150 cm³/cm³ at 65 atm and 298 K, conditions relevant to ANG. Here, we report a double-walled 2-fold interpenetrated diamondoid (dia) network, X-dia-6-Ni, [Ni₂L₄(μ-H₂O)]_n, comprising a new azo linker ligand, L^– (L^– = (E)-3-(pyridin-4-yldiazenyl)benzoate) and 8-connected dinuclear molecular building blocks. X-dia-6-Ni exhibited gas (CO₂, N₂, CH₄) and liquid (C8 hydrocarbons)-induced reversible transformations between its activated narrow-pore β phase and γ, a large-pore phase with ca. 33% increase in unit cell volume. Single-crystal X-ray diffraction (SCXRD) studies of the as-synthesized phase α, β, and γ revealed that structural transformations were enabled by twisting of the azo moiety and/or deformation of the MBB. Further insight into these transformations was gained from variable temperature powder XRD and in situ variable pressure powder XRD. Low-temperature N₂ and CO₂ sorption revealed stepped Type F–II isotherms with saturation uptakes of 422 and 401 cm³/g, respectively. X-dia-6-Ni exhibited uptake of 200 cm³/cm³ (65 atm, 298 K) and a high CH₄ working capacity of 166 cm³/cm³ (5–65 bar, 298 K, 33 cycles), the third highest value yet reported for an FMOM and the highest value for an FMOM with a Type F–II isotherm.

中文翻译：

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具有甲烷阶梯式等温线的双壁金刚石配位网络中的可逆相变


具有阶梯式等温线的柔性金属有机材料（FMOM）可以在吸附天然气（ANG）存储等存储应用中提供增强的工作能力。不幸的是，虽然已知 >1000 个 FMOM，但只有少数在 65 atm 和 298 K（与 ANG 相关的条件）下表现出 >150 cm ³ /cm ³ 的甲烷吸收量。在这里，我们报告了一种双壁2倍互穿金刚形（dia）网络，X-dia-6-Ni，[Ni ₂ L ₄ (μ-H ₂ O)] _n ，包含新的偶氮接头配体 L ^– (L ^– = (E)-3-(pyridin-4 -基二氮烯基)苯甲酸酯)和8-连接的双核分子构件。 X-dia-6-Ni表现出气体（CO ₂ 、N ₂ 、CH ₄ ）和液体（C8碳氢化合物）诱导的其活化之间的可逆转变窄孔 β 相和 γ，一种大孔相，约晶胞体积增加 33%。对合成时的 α、β 和 γ 相的单晶 X 射线衍射 (SCXRD) 研究表明，结构转变是通过偶氮部分的扭曲和/或 MBB 的变形实现的。通过变温粉末 XRD 和原位变压粉末 XRD 进一步了解了这些转变。低温 N ₂ 和 CO ₂ 吸附显示阶梯式 F-II 型等温线，饱和吸收量分别为 422 和 401 cm ³ /g。 X-dia-6-Ni 表现出 200 cm ³ /cm ³ (65 atm, 298 K) 的吸收量和 166 的高 CH ₄ 工作容量cm ³ /cm ³ （5–65 bar，298 K，33 个循环），FMOM 迄今为止报告的第三高值，也是 F 型 FMOM 的最高值–II 等温线。