Solvothermal reactions of cyclotriphosphazene-functionalized hexacarboxylate derivatives bearing different substituents (methoxy, chloro, bromo and methyl) with Ho(NO₃)₃·6H₂O gave rise to four new three-dimensional lanthanide metal–organic frameworks (Ln-MOFs). Single-crystal X-ray diffraction analyses reveal that they all feature rod-shaped Ho-carboxylate chains as inorganic secondary building units but display substituent-driven structural diversities instead of the isoreticular structures. N₂ adsorption and desorption studies show that among these Ln-MOFs, only the methoxy-modified Ln-MOF ZJNU-63 after activation exhibits permanent porosity. Furthermore, the gas adsorption properties of ZJNU-63 with respect to C₂H₂, C₂H₄, C₂H₆, CO₂, and CH₄ were systematically investigated, revealing its possible potential for natural gas purification. Although the separation performance is not very impressive compared to the other reported MOFs, ZJNU-63 presents a rare example of permanently porous Ln-MOFs constructed from flexible organic ligands displaying selective gas adsorption. Besides, ZJNU-63 can adsorb a large amount of C₄ hydrocarbons with uptake capacities ranging from 58.8 to 75.7 cm³ (STP) g⁻¹ at 298 K and 1 atm.

中文翻译：

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基于环三磷腈官能化的六羧酸酯衍生物的一系列棒状填充镧系-有机骨架的结构多样性和气体吸附特性†

带有不同取代基（甲氧基，氯，溴和甲基）的环三磷腈官能化六羧酸酯衍生物与Ho（NO ₃）₃ ·6H ₂ O的溶剂热反应产生了四个新的三维镧系金属有机骨架（Ln-MOF）。单晶X射线衍射分析表明，它们都以棒状的Ho-羧酸盐链为无机二级结构单元，但显示出取代基驱动的结构多样性，而不是等网状结构。N ₂吸附和解吸研究表明，在这些Ln-MOF中，只有经活化后甲氧基改性的Ln-MOF ZJNU-63才显示永久孔隙。此外，气体的吸附特性对ZJNU-63的C ₂ H ₂，C ₂ H ₄，C ₂ H ₆，CO ₂和CH ₄进行了系统研究，揭示了其在天然气净化方面的潜在潜力。尽管与其他已报道的MOF相比，分离性能不是很出色，但ZJNU-63却是一个罕见的永久多孔Ln-MOF的例子，它由具有选择性气体吸附作用的柔性有机配体构成。此外，ZJNU-63可以吸附大量C ₄碳氢化合物，吸收能力为58.8至75.7 cm ³（STP）g^-1在298 K和1个大气压下。