All‐Inorganic Ionic Porous Material Based on Giant Spherical Polyoxometalates Containing Core‐Shell K6@K36‐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-H2 O cluster {K42 (H2 O)60 } with core-shell K6 @K36 configuration is stabilized by 8 C3v -symmetry trivacant POMs [GeW9 O34 ]10- , forming a novel giant ionic alkali-metal-POM composite cluster {K42 Ge8 W72 O272 (H2 O)60 } with more than 100 metal centers. The incorporated 42-nuclearity K-H2 O cluster {K42 (H2 O)60 } exhibits the highest-nuclearity alkali-metal-water cluster known to date in POM chemistry. Further, the giant {K42 Ge8 W72 O272 (H2 O)60 } 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.