A highly selective host based on the pamoate ion

Five isostructural host-guest complexes based on the pamoate ion have been identified and characterised. The host framework is made up of hydrogen-bonded units of pamoate and 4-phenylpyridinium ions, held together by weak C-H center dot center dot center dot pi and stacking interactions, and in each complex the guest molecules reside in cavities within this framework. Although the host is not porous, it is thermally stable and also highly selective, encapsulating 1,4-dioxane preferentially over various other solvents.