Leaf-Inspired Host-Guest Complexation-Dictating Supramolecular Gas Sensors

We report unique conductive leaf-inspired (in particular,stomata-inspired)supramolecular gas sensors in which acetylated cyclodextrin derivativesrule the electric output. The gas sensors consist of polymers bearingacetylated cyclodextrin, adamantane, and carbon black. Host-guestcomplexes between acetylated cyclodextrin and adamantane correspondingto the closed stomata realize a flexible polymeric matrix. Effectiverecombination of the cross-links contributes to the robustness. Asgas sensors, the supramolecular materials detect ammonia as well asvarious other gases at 1 ppm in 10 min. The free acetylated cyclodextrincorresponding to open stomata recognized the guest gases to alterthe electric resistivity. Interestingly, the conductive device failedto detect ammonia gases at all without acetylated cyclodextrin. Themolecular recognition was studied by molecular dynamics simulations.The gas molecules existed stably in the cavity of free acetylatedcyclodextrin. These findings show the potential for developing wearablegas sensors.