A variety of combinatorially linkable units as disposition:† from a giant icosahedral Keplerate to multi-functional metal–oxide based network structures

In polyoxometalate chemistry a large variety of compounds, clusters and solid-state structures can be formed by linking together metal–oxygen building blocks. Interestingly, reactions based on libraries of virtual building blocks can be planned under appropriate conditions, resulting for instance in the high-yield synthesis of inorganic superfullerenes and giant ring-shaped, electron-rich, mixed-valence polyoxomolybdates with nanosized cavities. The latter species can continue to grow and also can be covalently linked together to form chains as well as layered mesoporous compounds with properties relevant for materials science. The largest polyoxometalate cluster obtained on the basis of such a growth process consists of 248 Mo atoms. Remarkably, such giant ring species can also act as hosts for other clusters forming new types of supramolecular compounds.