Self-assembly is a powerful technique for the bottom-up construction of discrete, well-defined nanoscale structures. Large multicomponent systems (with more than 50 components) offer mechanistic insights into biological assembly but present daunting synthetic challenges. Here we report the self-assembly of giant M24L48 coordination spheres from 24 palladium ions (M) and 48 curved bridging ligands (L). The structure of this multicomponent system is highly sensitive to the geometry of the bent ligands. Even a slight change in the ligand bend angle critically switches the final structure observed across the entire ensemble of building blocks between M24L48 and M12L24 coordination spheres. The amplification of this small initial difference into an incommensurable difference in the resultant structures is a key mark of emergent behavior.

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Bottom-up construction of giant structures by the self-assembly of a large number of components (n = 100) has been a daunting challenge. Here, Fujita and colleagues report the self-assembly of a spherical metal polyhedron, possessing a hitherto unreported icosidodecahedron geometry with 30 vertices and 60 edges. The authors succeeded in controlling the self-assembly by intensive tuning of the ligand flexibility. X-ray crystallographic analysis confirmed that the complex is the largest well-defined spherical molecular capsule, comparable with the size of a typical protein.