The designability and adjustability of the pore structure are vital advantages of metal–organic framework (MOF) materials for separation. Their exploration in the field of membrane separation is still inadequate, especially for the regulation of the pore environment based on the inorganic secondary building unit (SBU). In this work, we have studied the effect of the pore environment regulated by the SBU on the gas separation performance of MOF membranes for the first time. The Fe₃(μ₃-O)(CH₃COO)₆ SBU of the parent framework (soc-MOF, a stable microporous Fe-MOF) was in situ modified with imidazole (IM) molecules to construct the soc-MOF-IM polycrystalline membrane. The exact location of the incorporated IM and the narrowed pore size are observed based on the determined crystal structure. The gas solubility, diffusivity and separation performance of the two membranes are evaluated. Compared to the soc-MOF membrane with a H₂/CO₂ selectivity of 6, the soc-MOF-IM polycrystalline membrane possesses a significantly enhanced H₂/CO₂ selectivity (48), which is mainly attributed to the triggered molecular sieving effect. Thanks to the facile introduction of functional molecules and precise adjustment of the pore environment, SBU modification can be a powerful strategy to improve the separation performance of MOF membranes.

中文翻译：

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通过修改辅助建筑单元以改善气体分离效果，设计金属有机骨架膜的孔隙环境

孔结构的可设计性和可调节性是用于分离的金属有机框架（MOF）材料的重要优势。他们在膜分离领域的探索仍然不足，特别是对于基于无机二级结构单元（SBU）的孔隙环境的调节。在这项工作中，我们首次研究了由SBU调节的孔环境对MOF膜的气体分离性能的影响。中的Fe ₃（μ ₃ -O）（CH ₃ COO）₆父框架（SBU的SOC-MOF是，稳定的微孔的Fe-MOF）在原位与咪唑（IM）分子修饰以构建SOC-MOF-IM多晶膜。基于确定的晶体结构，观察到掺入的IM的确切位置和缩小的孔径。评价了两种膜的气体溶解度，扩散率和分离性能。与H ₂ / CO ₂选择性为6的soc-MOF膜相比，soc-MOF-IM多晶膜具有显着提高的H ₂ / CO ₂选择性（48），这主要是由于触发了分子筛分作用。得益于功能分子的简便引入和对孔环境的精确调节，SBU修饰可以成为提高MOF膜分离性能的有效策略。