Abstract Insertion of polymers into microporous metal–organic frameworks (MOFs) appeared recently as a powerful strategy to accomplish very difficult separations. However, the dynamics of their insertion remains to be fully unravelled. In this article, we describe the spontaneous insertion of poly(ethylene glycol) (PEG) into a flexible MOF. Thanks to the structural changes upon PEG insertion, in situ powder X-ray diffraction (PXRD) analysis could be performed. For PEGs with identical main chains, the insertion speed was strongly dependent on the nature of the terminus. Furthermore, a concentration dependence for terminal groups was observed, providing insight into the pore-opening mechanism, and suggesting a mildly cooperative terminus-first insertion. This establishes polymers as very valuable tools to study MOF dynamics, as their extended size allows domains with clearly different properties within the same macromolecule.

中文翻译：

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熔融聚乙二醇的末端依赖性插入到柔性金属有机框架中

摘要 将聚合物插入微孔金属有机框架 (MOF) 中最近出现作为实现非常困难的分离的强大策略。然而，它们插入的动态仍有待完全解开。在本文中，我们描述了聚（乙二醇）（PEG）自发插入到灵活的 MOF 中。由于 PEG 插入后的结构变化，可以进行原位粉末 X 射线衍射 (PXRD) 分析。对于具有相同主链的 PEG，插入速度在很大程度上取决于末端的性质。此外，观察到末端基团的浓度依赖性，提供了对开孔机制的深入了解，并表明了温和的末端先插入。这使聚合物成为研究 MOF 动力学的非常有价值的工具，