All‐Inorganic Ionic Porous Material Based on Giant Spherical Polyoxometalates Containing Core‐Shell K6@K36‐Water Cage

Abstract 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 2 O cluster {K 42 (H 2 O) 60 } with core–shell K 6 @K 36 configuration is stabilized by 8 C 3 v ‐symmetry trivacant POMs [GeW 9 O 34 ] 10− , forming a novel giant ionic alkali‐metal‐POM composite cluster {K 42 Ge 8 W 72 O 272 (H 2 O) 60 } with more than 100 metal centers. The incorporated 42‐nuclearity K‐H 2 O cluster {K 42 (H 2 O) 60 } exhibits the highest‐nuclearity alkali‐metal‐water cluster known to date in POM chemistry. Further, the giant {K 42 Ge 8 W 72 O 272 (H 2 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.