Aqueous assembly of a (pseudo)rotaxane with a donor–π–acceptor axis formed by a Knoevenagel condensation

Abstract

The incorporation of a linear D–π–A “push–pull” chromophore synthesized by a Knoevenagel condensation as axle of a rotaxane is reported. While the introduction of the mechanical stoppers by the reversible and thermodynamically controlled Knoevenagel reaction turned out to be challenging, mechanical fixation of the superstructure is achieved by “click” chemistry in aqueous solution. The isolated rotaxane with a red- to NIR-emitting dye as axle displays enhanced emission in aqueous buffered media compared to the unthreaded model chromophore.