Stereodynamics of E/Z isomerization in rotaxanes through mechanical shuttling and covalent bond rotation

We report on a set of rotaxanes with symmetrical axles equipped with a central amide group that installs E/Z stereoisomerism owing to the ring position along the axle. Isomerization by concomitant rotation about the amide bond and ring shuttling along the axle was thoroughly characterized in different solvents. The results trigger a discussion on core concepts, such as microscopic reversibility and transition state theory, and provide insights for designing molecules capable to transform and transmit motion between subcomponents.