Controlling the Reactivity of the [P₈ W₄₈ O₁₈₄ ]^40- Inorganic Ring and Its Assembly into POMZite Inorganic Frameworks...

The construction of pure-inorganic framework materials with well-defined design rules and building blocks is challenging. In this work, we show how a polyoxometalate cluster with an integrated pore, based on [P₈ W₄₈ O₁₈₄ ]^40- (abbreviated as {P₈ W₄₈ }), can be self-assembled into inorganic frameworks using silver ions, which both enable reactions on the cluster as well as link them together. The {P₈ W₄₈ } was found to be highly reactive with silver ions resulting in the in situ generation of fragments, forming {P₉ W₆₃ O₂₃₅ } and {P₁₀ W₆₆ O₂₅₁ } in compound (1) where these two clusters co-crystallize and are connected into a POMZite framework with 11 Ag⁺ ions as linkers located inside clusters and 10 Ag⁺ linking ions situated between clusters. Decreasing both the concentration of Ag⁺ ions, and the reaction temperature compared to the synthesis of compound (1), leads to {P₈ W₅₁ O₁₉₆ } in compound 2 where the {P₈ W₄₈ } clusters are linked to form a new POMZite framework with 9 Ag⁺ ions per formula unit. Further tuning of the reaction conditions yields a cubic porous network compound (3) where {P₈ W₄₈ } clusters as cubic sides are joined by 4 Ag⁺ ions to give a cubic array and no Ag⁺ ions were found inside the clusters.