Acid/Base-controlled supramolecular switch

Abstract

A rotaxane-like complex incorporating a hydroquinone-intercepted acyclic polyether chain terminated by tert-butylaniline rings and encircled by cyclobis(paraquat-p-phenylene) self-assembles spontaneously in acetonitrile solution from which it can be crystallized. Protonation of the nitrogen atoms of the guest is accompanied by the complete dissociation of the supramolecular complex into its free components. Addition of a base restores the original equilibrium affording back the rotaxane-like complex.