A high-yield synthesis and acid-base response of phosphate-templated [3]rotaxanes.

Anion-templated rotaxanes are a rare class of functional organic molecules capable of novel switching and mechanical behaviors. Yet, investigations of these properties are limited by existing synthetic strategies. We show a high-yielding synthesis (80%) of [3]rotaxanes using shape-persistent macrocycles, cyanostars, and anionic organo-phosphate templates catalyzed by low steric-demand click chemistry. The reaction yields correlate with the template's binding affinities. Use of longer linkers relieves steric congestion to enable a reversible acid-base response, opening the way to molecular switching.