A nanometre-sired hexahedral coordination capsule assembled from 24 components

Molecular capsules consist of closed, hollow frameworks within which encapsulated molecules are isolated from interaction with external molecules', In this environment, otherwise reactive molecules can be stabilized(2-5). Although some molecular capsules have been prepared by conventional synthetic chemistry(1), recent progress in non-covalent synthesis has allowed the creation of capsules held together by hydrogen bonds(6-9). Hero we report the use of transition-metal-based coordination chemistry(10-19) to assemble a stable, nanometre-scale capsule from 24 small components: 18 metal ions and six triangular ligands, The capsule is roughly hexahedral and comprises six edge-sharing triangles with two metal ions on each edge. The internal space has a volume of 900 Angstrom(3) and is fully closed to all but very small molecules.