Self-Templating and In Situ Assembly of a Cubic Cluster-of-Clusters Architecture Based on a {Mo24Fe12} Inorganic Macrocycle

Engineering self‐templating inorganic architectures is critical for the development of bottom‐up approaches to nanoscience, but systems with a hierarchy of templates are elusive. Herein we describe that the cluster‐anion‐templated (CAT) assembly of a {CAT}⊂{Mo24Fe12} macrocycle forms a giant ca. 220 nm3 unit cell containing 16 macrocycles clustered into eight face‐shared tetrahedral cluster‐of‐clusters assemblies. We show that {CAT}⊂{Mo24Fe12} with different CATs gives the compounds 1–4 for CAT=Anderson {FeMo6} (1), Keggin {PMo12} (2), Dawson {P2W18} (3), and {Mo12O36(HPO3)2} (4) polyoxometalates. “Template‐free” assembly can be achieved, whereby the macrocycle components can also form a template in situ allowing template to macrocycle to superstructure formation and the ability to exchange the templates. Furthermore, the transformation of template clusters within the inorganic macrocycle {Mo24Fe12} allows the self‐generation of an uncapped {Mo12O36(HPO3)2} in compound 4. Be my guest: A series of {Mo24Fe12} macrocycles featuring supramolecular tetrahedron architectures is formed via anion‐templated self‐assembly. Transformation between macrocycles is realized by template exchange. The {Mo24Fe12} is used as a confined reaction vessel for the in situ generation of uncapped {Mo12(HPO3)2} within the macrocycle.