Dynamic Pendulum Effect of an Exceptionally Flexible Pillared‐Layer Metal‐Organic Framework†.

Main observation and conclusion: Magnifying the controllable directional motions of molecular machines to the macroscopic levels is a significant topic for chemists. Flexible metal–organic frameworks with long‐range order and responsive structural transformation under external stimuli may be an appropriate platform for achieving the target. By taking advantage of the single‐crystal to single‐crystal manner of soft porous crystals, we utilize single‐crystal X‐ray diffraction to directly observe the dynamic structural inversion of a new three‐fold interpenetrated pillared‐layer metal‐organic framework [Co(edba)(bpy)] (MCF‐83, H2edba = 4,4'‐(ethyne‐1,2‐diyl)dibenzoic acid, bpy = 4,4'‐bipyridine). More interestingly, the dynamic inversions of the pillars and layers are selectively guest‐controllable and independent, allowing precise control of the directional shape changes, which is the key of constructing intelligent materials to accomplish a complex task. The mechanism is further studied by combining the X‐ray diffraction analyses, sorption measurements and molecular simulations. [ABSTRACT FROM AUTHOR]