Solvent-Modulated Formation of “Pac-man” and Capsular Host–Guest Bilayers from a Dicationic Ionic Liquid and C-Butylpyrogallol[4]arene

Abstract

The pyrogallol[4]arenes have been shown to act as versatile host macrocycles for a wide variety of guest molecules, including the imidazolium-based cations of ionic liquids. This report demonstrates the use of alkyl-linked geminal dications in the design of bilayers comprising dimeric host–guest complexes. The pivotal role of solvent choice in controlling the resultant solid-state structure is particularly highlighted. The synthesis and single-crystal X-ray diffraction structures of two dimeric host–guest cocrystals generated by the use of different solvents while employing identical host and guest species are presented to illustrate this point. In one solvent, a “Pac-man”-type dimeric host–guest complex is assembled into bilayer galleries. With a switch to an alternate crystallization solvent, a bilayer-type structure in which each layer is composed of alternating complexes of a capsule and two “offset dimers” is instead constructed.