An M ₁₈L ₂₄ stellated cuboctahedron through post-stellation of an M ₁₂L ₂₄ core

Platonic and Archimedean polyhedra, well-known to mathematicians, have been recently constructed by chemists at a molecular scale by defining the vertices and the edges with metal ions (M) and organic ligands (L), respectively. Here, we report the first synthesis of a concave-surface ' stellated polyhedrong', constructed by extending the faces of its precursor polyhedron until they intersect, forming additional nodes. Our approach involves the formation of an M ₁₂L ₂₄ cuboctahedron core, the linkers of which each bear a pendant ligand site that is subsequently able to bind an additional metal centre to form the stellated M ₁₈L ₂₄ cuboctahedron. During this post-stellation process, the square faces of the M ₁₂L ₂₄ core are closed by coordination of the pendant moieties to the additional metal centres, but they are re-opened on removing these metals ions from the vertices. This behaviour is reminiscent of the analogous metal-triggered gate opening-closing switches found in spherical virus capsids.