Supramolecular assemblies constructed from inverted cucurbituril and lanthanide cations: synthesis, structure and sorption properties†
The interaction of a series of lanthanide cations (Ln3+) with inverted cucurbituril (iQ) in the presence of [ZnCl4]2− anions as a structure-directing agent have been investigated. Single-crystal X-ray diffraction analysis has revealed that the [ZnCl4]2− anions surround the iQ molecules via the outer surface interactions of iQ. This results in the formation of honeycomb-like frameworks, and ultimately linear supramolecular chains of iQ in which Ln3+ cations occupy voids within the framework. Moreover, these iQ/Ln3+-based supramolecular assemblies exhibit excellent thermal stability as well as permanent porosity, and in one case screening revealed a high CH3OH uptake capacity compared with other porous organic materials assembled solely through hydrogen bonding under ambient conditions.