Triple Stack of a Viologen Derivative in a CB[10] Pair

Abstract

A viologen-phenylene-imidazole (<b>VPI</b>) conjugate, previously shown to be singly complexed by CB[7] and doubly bound by CB[8], is herein shown to form antiparallel triple stacks in water with cucurbit[10]uril (CB[10]), pairwise complexing the guest trimer. The quinary host:guest 2:3 complex showed features assignable to charge-transfer interactions. Under reductive conditions, CB[10] could solubilize a <b>VPI</b> radical, even though CB[10] and reduced <b>VPI</b> are almost insoluble, thereby illustrating a possible new application for CB[10].