Visualizing Structural Transformation and Guest Binding in a Flexible Metal–Organic Framework under High Pressure and Room Temperature

Hui Yang, Feng Guo, Prem Lama, Wen-Yang Gao, Hui Wu, Leonard J. Barbour, Wei Zhou, Jian Zhang, Briana Aguila, Shengqian Ma
2018 ACS Central Science  
Understanding the effect of gas molecules on the framework structures upon gas sorption in porous materials is highly desirable for the development of gas storage and separation technologies. However, this remains challenging for flexible metal−organic frameworks (MOFs) which feature "gate-opening/gate-closing" or "breathing" sorption behaviors under external stimuli. Herein, we report such a flexible Cd-MOF that exhibits "gating effect" upon CO 2 sorption. The ability of the desolvated
more » ... Cd-MOF to retain crystal singularity under high pressure enables the direct visualization of the reversible closed-/openpore states before and after the structural transformation as induced by CO 2 adsorption/desorption through in situ single-crystal X-ray diffraction experiments. The binding sites of CO 2 molecules within the flexible MOF under high pressure and room temperature have also been identified via combined in situ single-crystal X-ray diffraction and powder X-ray diffraction studies, facilitating the elucidation of the states observed during gate-opening/gate-closing behaviors. Our work therefore lays a foundation to understand the high-pressure gas sorption within flexible MOFs at ambient temperature, which will help to improve the design efforts of new flexible MOFs for applications in responsive gas sorption and separation.
doi:10.1021/acscentsci.8b00378 pmid:30276253 pmcid:PMC6161039 fatcat:ch4qfdme6rdu3gwg346dmlrf4i