The key parameters governing the mechanical stability of highly porous materials such as metal–organic frameworks (MOFs) are yet to be clearly understood. This study focuses on the role of the linker connectivity by investigating the mechanical stability of MIL-100(Cr), a mesoporous MOF with a hierarchical structure and a tritopic linker, and comparing it to MIL-101(Cr) having instead a ditopic linker. Using synchrotron X-ray diffraction and infrared spectroscopy, we investigate the high-pressure behavior of MIL-100(Cr) with both solid and fluid pressure transmitting media (PTM). In the case of a solid medium, MIL-100(Cr) undergoes amorphization at about 0.6 GPa, while silicone oil as a PTM delays amorphization until 12 GPa due to the fluid penetration into the pores. Both of these values are considerably higher than those of MIL-101(Cr). MIL-100(Cr) also exhibits a bulk modulus almost ten times larger than that of MIL-101(Cr). This set of results coherently proves the superior stability of MIL-100(Cr) under compression. We ascribe this to the higher connectivity of the organic linker in MIL-100(Cr), which enhances its interconnection between the metal nodes. These findings shed light on the importance of linker connectivity in the mechanical stability of MOFs, a relevant contribution to the quest for designing more robust MOFs.

中文翻译：

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探索配体连接性在 MOF 机械稳定性中的作用：以 MIL-100(Cr) 为例

控制金属有机框架（MOF）等高多孔材料机械稳定性的关键参数尚不清楚。本研究通过研究 MIL-100(Cr)（一种具有分层结构和三位连接体的介孔 MOF）的机械稳定性，并将其与具有双位连接体的 MIL-101(Cr) 进行比较，重点关注连接体连接的作用。利用同步加速器 X 射线衍射和红外光谱，我们研究了 MIL-100(Cr) 在固体和流体压力传输介质 (PTM) 下的高压行为。在固体介质的情况下，MIL-100(Cr)在约0.6 GPa下发生非晶化，而硅油作为PTM由于流体渗透到孔隙中而将非晶化延迟至12 GPa。这两个值均远高于 MIL-101(Cr) 的值。 MIL-100(Cr) 的体积模量几乎是 MIL-101(Cr) 的十倍。这组结果一致证明了 MIL-100(Cr) 在压缩下具有卓越的稳定性。我们将此归因于 MIL-100(Cr) 中有机连接体的更高连接性，这增强了金属节点之间的互连。这些发现揭示了连接体连接在 MOF 机械稳定性中的重要性，这对设计更坚固的 MOF 做出了相关贡献。