Insights into the Flexibility of ZIF-7 and Its Structural Impact in Alcohol Adsorption

The flexibility of zeolitic imidazolate frameworks (ZIFs) is often interpreted as a result from their bulky linkers, the free rotations of which sometimes generate enough momentum to fluctuate the pore opening. In some extreme cases, all metal centers’ atomic positions are changed correspondingly, and in a three-dimensional network, it is intriguing how the displacement happens coordinately. Here, we bridged the learnings from zeolite sodalite (SOD) topology and applied it in studying ZIF-7’s structural transformation. We discovered a new extra-large pore ZIF-7 following the same rhombohedral symmetry. We have examined side-by-side the structural changes from X-ray diffraction (XRD) and solid-state NMR and successfully identified the precise adsorption sites. We applied ZIF-7’s flexibility in alcohol separation and used a series of alcohol molecules to study the adsorption mechanism.