Gadolinium(iii)-mediated multi-component confinement of imidazolium cations in p-sulfonated calix[4]arene

Abstract

A molecular capsule based on two p-sulfonated calix[4]arenes along with Gd(III) coordination spheres arranged around the equator of the capsule effectively confined a 1-butyl-3-methylimidazolium cation, affording a relatively small capsule size. For a bis-imidazolium cation, only one of the imidazole rings is included in the calixarene cavity with the other ring extending towards a sulfonate group of an adjacent calixarene. Thus, the included molecule breaches the equatorial seam of the larger capsule, but here there is no incorporation of Gd(III). In both complexes the capsules themselves are arranged such that the calixarenes are in bilayer arrangements, with (3-methoxyphenyl)triphenylphosphonium cations at the interface of the hydroxyl groups of the calixarene. The interplay of the components was also investigated using Hirshfeld surface analysis.