Nanometer size fullerene-like molecules composed of vanadium and oxygen can be synthesized. We can assemble the square pyramidal VO5 units in a spherical manner that all the pyramidal bottoms are facing at the center of the sphere. The anionic guest sits at the center through the weak interactions with the peripheral vanadium cations, because all the bottoms of the pyramids are facing inside the sphere. The inorganic host-guest complexes shows multistep redoxes and catalytic activity. The oxidation state of vanadium is V(V) or V(IV), and it preferes a mixed valence state with multiple one-electron reversible redoxes. V10, V14, V15, V16, V18, V22 and V34 frameworks have been reported. The ball holds a variety of guest anion inside the anionic molecule.
