Molecular Switch Based on Very Weak Association between BPX26C6 and Two Recognition Units

A [2]rotaxane has been constructed through metal ion-templated pseudorotaxane formation from a weakly interacting host (bis-p-xylyl[26]crown-6)/guest (diphenylurea derivative) complex and post-assembly modification to form another weakly interacting tertiary ammonium ion recognition site for the host. The combination of this pair of weakly interacting components allowed bifunctional (pH, Na+ ions) switching of the crown ether unit, highlighting the potential applicability of weakly associated components within molecular switches.