Molecular-Gate Strategy for Solid-State Selective Recognition of Dioxane Isomers via Reversible Host-Guest and...

Achieving highly selective molecular recognition in the solid state remains a major challenge in supramolecular chemistry. Herein, we introduce a molecular-gate strategy that dynamically amplifies intrinsic solid-state recognition selectivity in a macrocyclic host-guest system. A perethylated leaning pillar[6]arene (EtLP6) accommodates both 1,3- and 1,4-dioxane isomers in the solid state, exhibiting only modest inherent selectivity. Remarkably, incorporation of an independent, reversible, charge-transfer-active molecular gate, tetrafluoroterephthalonitrile (TFTN), converts this weak preference into highly selective recognition through competitive binding and solid-state reorganization. The stronger-binding 1,4-dioxane displaces TFTN to open the gate and form a host-guest complex, whereas the weaker-binding 1,3-dioxane stabilizes a gated CT assembly that suppresses complexation. This gate-controlled process couples selective recognition with switchable CT interactions, enabling vapochromic discrimination of dioxane isomers. Furthermore, sequential competitive binding enables dynamic regulation of solid-state assemblies, including room-temperature-controlled guest release, and host recyclability. This work establishes molecular gating as a general and conceptually simple strategy for regulating selectivity and functionality in solid-state macrocyclic host-guest systems.