Rotary Motion Controls Translational Motion in a Single Molecular Machine

Molecular machines bring the mechanical world to nanoscale dimensions and, reminiscent of biological machines, allow directional movement and precise dynamic and adaptive functions. Transmission and coupling of distinct motions are essential for future advanced nanomachinelike operations, but the control of translational motion by rotary motion remains highly challenging. Here we show that two distinct types of motion with large amplitude are integrated in one single molecular machine. A rotaxane shuttling system, with a molecular rotary motor intrinsic to its axle, enables light-powered rotary motion which significantly affects the translational motion of the ring both regarding speed of linear movement and shuttling directions. The dynamic control of two distinct motions is due to the geometrical changes during the motor’s rotation as both steric hindrance and non-covalent interactions between the motor unit and the shuttling ring change upon rotation powered by light. In-depth computational studies support the mechanism of how shuttling of the ring is affected by rotation of the motor. These findings represent an important milestone towards the future design of complex synthetic molecular machines with integrated mechanical functions.