Organic-inorganic hybrid polyhedra that can serve as supermolecular building blocks

[V₄O₈X(COO)₄]^z- or [V ₅O₉X(COO)₄]^2- polyoxometallate anions can function as 4-connected nodes that assemble with 3-connected organic nodes (1,3,5-benzentricarboxylate) to afford small cubicuboctahedral hybrid nanoballs (hyball-3, -4, -5) in high yield. The resulting polyhedral cages exhibit 550 ų internal volumes and gas sorption measurements reveal that solid forms of the hyballs are permanently porous. The exterior surfaces of the hyballs are suited for further self-assembly and hyball-3 can serve as an octahedral supermolecular building block for the generation of primitive cubic (pcu) nets via two types of linkage: hydrogen bonds or coordination bonds.