All-Inorganic Ionic Porous Material Based on Giant Spherical Polyoxometalates Containing Core-Shell K @K -Water Cage.

This work demonstrates that the use of high-negative and high-symmetry lacunary polyoxometalates (POMs) for the clustering of alkali metal ions is a feasible strategy not only for the formation of rare high-nuclearity alkali-metal clusters but also for the construction of new-type all-inorganic ionic porous materials. By the strategy, an unprecedented high-nuclearity K-H O cluster {K (H O) } with core-shell K @K configuration is stabilized by 8 C -symmetry trivacant POMs [GeW O ] , forming a novel giant ionic alkali-metal-POM composite cluster {K Ge W O (H O) } with more than 100 metal centers. The incorporated 42-nuclearity K-H O cluster {K (H O) } exhibits the highest-nuclearity alkali-metal-water cluster known to date in POM chemistry. Further, the giant {K Ge W O (H O) } clusters can be linked by another kind of alkali metal ions Na to generate a fascinating three-dimensional all-inorganic ionic porous framework with high chemical stability, proton conductivity, and water vapor adsorption.