Self-Templating and In Situ Assembly of a Cubic Cluster-of-Clusters Architecture Based on a {Mo24 Fe12 } Inorganic Macrocycle

Abstract

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}⊂{Mo24 Fe12 } macrocycle forms a giant ca. 220 nm(3) unit cell containing 16 macrocycles clustered into eight face-shared tetrahedral cluster-of-clusters assemblies. We show that {CAT}⊂{Mo24 Fe12 } with different CATs gives the compounds 1-4 for CAT=Anderson {FeMo6 } (1), Keggin {PMo12 } (2), Dawson {P2 W18 } (3), and {Mo12 O36 (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 {Mo24 Fe12 } allows the self-generation of an uncapped {Mo12 O36 (HPO3 )2 } in compound 4.

Keywords: anion templating; host-guest chemistry; macrocycles; polyoxometalates; supramolecular cages.