Hierarchical design of nanostructured materials based on polyoxometalates

The construction of nanostructured materials with advanced functions by the self-organization of molecular building blocks is one of the key topics in modern materials chemistry. This review describes our concept of the hierarchical design of polyoxometalate (POM)-based compounds with nanosized spaces: (1) syntheses of building blocks (POMs and counter cations), (2) directing the self-organization of building blocks to form crystalline materials with nanosized spaces, and (3) kinetic control of the self-organization process to introduce nanosized space into the dense nonporous crystal, with emphasis on (2). Our recent results on the construction of nanosized spaces within the POM-based compounds with controlled size, volume, shape, and affinity, and their functions are presented.