Organic Cage Encapsulated Within Metal Cluster‐Based Open Frameworks: A Single‐Crystal Host‐in‐Host Material with Inter‐Host Charge Cooperation

Abstract Integrating dissimilar building units of discrete organic cages and inorganic clusters into single‐crystal supramolecular frameworks with tailored architectures and synergistic functions presents a significant challenge. Here, we presented our discovery of achieving such hybrids through electrostatically driven self‐assembly of cationic ammonium organic cages with anionic lead iodide clusters. Notably, by carefully modulating the size, shape, and composition of cationic organic cages, we have constructed an integrated porous host‐in‐host architecture. In this system, the internal cationic cage snugly resided, encapsulated within the external network constructed from anionic lead iodide clusters. This unique nested hierarchy showcased enhanced interhost interactions facilitated by electrostatic forces, which intricately tailored the electronic structure of the outer lead iodide moiety. As a result, the hybrid demonstrated distinguished photophysical properties, including efficient oxygen activation and enhanced photothermal conversion capability, as confirmed by comprehensive experimental and theoretical analyses. The critical role of interhost electrostatic interactions was further demonstrated through a systematic comparison with a structurally similar host‐in‐host architecture comprising lead iodide clusters and neutral amine cages. Furthermore, the integrated and compartmentalized dual‐host served as spatially isolated dual active sites for cascade reactions, exhibiting 33–47‐folds enhancement in activity compared to structural counterparts lacking charge cooperation.