Guest-Dependent Single-Crystal-to-Single-Crystal Phase Transitions in a Two-Dimensional Uranyl-Based Metal–Organic Framework

Two-dimensional metal–organic frameworks (2D-MOFs) have shown promise in gas storage and separation applications due to their structural isomerism in response to external stimuli such as temperature, mechanical pressure, and/or guest molecules. Here, we report the guest-dependent phase transitions of a uranyl-based 2D-MOF, NU-1302, observed as single-crystal-to-single-crystal transformations. Different stacking configurations of the same structure were observed in DMF and ethanol, and after supercritical CO2 activation. The structural isomerism upon exposure to different solvents and when solvent-free demonstrated the ability of this system to respond to guests by shifting neighboring 2D sheets, resulting in the expansion or contraction of one-dimensional channels.