Cooperative outer-surface recognition extends host-guest chemistry for high-capacity molecular separation beyond cavity inclusion

The separation of azeotropic and structurally similar mixtures remains a fundamental challenge for conventional porous materials. Supramolecular host-guest chemistry provides exceptional recognition precision but is inherently limited by discrete cavity-confined binding. Here, we establish a strategy that extends host-guest recognition beyond cavity inclusion by activating cooperative interactions at the outer surfaces of macrocyclic hosts. Using cucurbit[7]uril (Q[7]) as a model system, we demonstrate that exposed outer surfaces can serve as amplifying recognition interfaces, where initial guest binding triggers subsequent molecular recruitment through cooperative aromatic interactions. Immobilization of Q[7] on magnetic Fe₃O₄ nanoparticles suppresses aggregation and enables synergistic cavity- and outer-surface-mediated recognition. The resulting material achieves highly selective and efficient separation of benzene (Ben) from n-heptane (n-Hep) with enhanced adsorption capacity and recyclability. This work suggests outer-surface-mediated cooperative recognition as a general paradigm for designing supramolecular separation materials beyond cavity-centric host-guest chemistry.