Self-Assembly of Organic Cages into 1D and 2D Hierarchical Superstructures Driven by Halogen-Bonding Interactions

Great efforts have been devoted to designing organic molecular cages with a 3D topology and shape persistence. Yet, how to harness these cages as atomically precise, nanosized building blocks to construct hierarchical superstructures remains underexplored. Here we report a strategy that exploits functionalized organic cages as premade nanobuilding units and connects them into self-assemblies with structural hierarchy and tunable dimensionality. Using a triphenylphosphine oxide (Ph3P=O)-paneled trigonal prism as vertex-decorated cage to connect with iodobenzene-capped bridging ligands (Ar-I), they can constitute infinite cage-based superstructures through weak P=O<middle dot><middle dot><middle dot>I-Ar halogen-bonding interactions. Regulating the ligand configuration and valence can dictate the connecting direction to form 1D cage-to-chain (nanofilament) and 2D cage-to-framework (nanosheet) architectures and further hierarchically assemble into microwire and microplate materials. The cage-connecting assemblies possess larger void volume and dual porosity compared to their parent cage itself, which can be applied in selective encapsulation and bisubstrate cascade catalysis.