Abstract
Control over the binding properties of anion receptors by external stimuli can be advantageous in various applications such as extraction and transport processes. Toward a light-responsive anion receptor with high binding affinity and selectivity, a stiff-stilbene photoswitch is incorporated into the macrocycle of a mechanically interlocked, chloride-binding [2]rotaxane structure. UV-Vis and (1)H NMR studies show reversible transformation between Z/E-isomers upon light irradiation, causing changes in motional dynamics and binding affinity. Photoswitching also takes place in the presence of chloride, as monitored by (1)H NMR spectroscopy, which results in its concomitant uptake and release. Our results show the suitability of rotaxanes as light-responsive ion receptors, which could serve as prototypes for supramolecular pumps.