Parking and Restarting a Molecular Shuttle In Situ

Herein we report an easy‐to‐synthesize [2]rotaxane, which incorporates two ionic monopyridinium stations and one 2,2′‐bipyridine station as the shaft of the dumbbell‐shaped component and a bis‐p‐xylyl[26]crown‐6 (BPX26C6) unit as the macrocyclic component. In this molecular shuttle, the BPX26C6 unit can be docked selectively on either the central 2,2′‐bipyridine station or one of the two terminal pyridinium stations, and subsequently, returned to its shuttling molecular motion through the in situ addition of simple reagents (acid/base or metal ion/metal‐ion‐complexing ligand pairs). Which station for the shuttle? The in situ control of a molecular shuttle is reported in which the macrocycle can be selectively docked on either the central or one of the two terminal stations, and subsequently resume its shuttling molecular motion through the addition of complementary reagent pairs (see figure).