Supramolecular Polymers, Based on Crown Ether Recognition

Crown ethers are macrocyclic host molecules, which can form inclusion complexes with appropriate guests. Such host–guest complexes represent one of the true corner stones of supramolecular chemistry, and dynamic/reversible pseudorotaxanes as well as stable rotaxanes are widely known. In an analogous fashion, polypseudorotaxanes and polyrotaxanes have been assembled and studied with respect to their stimuli-responsive behavior. The dynamics of these supramolecular polymers are today referred to as “molecular machines” or “molecular muscles.” Going beyond the stimuli-responsive and self-healing applications, also organic–inorganic hybrid materials, chemical sensors, or biomedical applications have to be named in the context of supramolecular polymers, based on crown-ether recognition.