Defect‐Guided Assembly of Aperiodic and Flexible Metal–Organic Frameworks From Pre‐Formed Cages

ABSTRACT Controlling the spatial distribution of defects in metal–organic frameworks (MOFs) remains a fundamental challenge in defect engineering. Here, we report a cage‐directed assembly strategy that enables the programmed introduction of topologically correlated defects and induces aperiodicity in HKUST‐1‐type frameworks. Pre‐synthesised Rh(II) metal–organic cages or polyhedra (MOPs) act as persistent cavities that template the formation of HKUST‐1‐based networks containing linker‐induced Cu‐vacancy domains confined within discrete cuboctahedral cavities. The use of dicarboxylate linkers, in which one carboxylate group is missing compared to the original 1,3,5‐benzenetricarboxylate linker, gives rise to nine distinct local defect configurations that are independently distributed throughout the lattice. This results in an aperiodic framework with preserved long‐range crystallinity. The resulting materials exhibit hierarchical micro–mesoporosity, reversible loss and recovery of crystallinity, and a pronounced solvent‐induced breathing response. This work demonstrates that combining pre‐formed cages with linkers with reduced connectivity can be a new strategy to localise defects and access aperiodic MOFs with emergent structural adaptability.