Cyclic Ether Contaminant Removal from Water Using Nonporous Adaptive Pillararene Crystals via Host-Guest Complexation at the Solid-Solution Interface.

The removal of soluble cyclic ether contaminants, such as dioxane and THF, produced in industrial chemical processes from water is of great importance for environmental protection and human health. Here we report that nonporous adaptive crystals of perethylated pillar[5]arene () and pillar[6]arene () work as adsorbents for cyclic ether contaminant removal via host-guest complexation at the solid-solution interface. Nonporous crystals have the ability to adsorb dioxane from water with the formation of 1:2 host-guest complex crystals, while crystals cannot. However, both guest-free and crystals remove THF from water with having a better capacity. This is because forms a 1:2 host-guest complex with THF via host-guest complexation at the solid-solution interface while forms a 1:1 host-guest complex with THF. also shows the ability to selectively remove dioxane from water even in the presence of THF. Moreover, the reversible transitions between nonporous guest-free and structures and guest-loaded structures make them highly recyclable.