The switching of rotaxane-based motors.

Linear molecular motors have recently attracted considerable interest. In this paper we use molecular dynamics simulations to investigate the structural and energetic properties of neutral and oxidized [2]rotaxane motors. We first consider a neutral structure to identify the stable configuration of a bistable [2]rotaxane whose ring component is on the tetrathiafulvalene (TTF) recognition site, followed by a study of the dynamic switching process of an oxidized [2]rotaxane. The study shows that for a neutral structure the ring component stays at the TTF station in both free and constrained situations. When the station is oxidized, the ring is pushed to the other station and the dynamic switching process finishes in about 10 ns. By comparing the results for the cases of free and fixed ends, the simulations show that structural deformation plays an important role during the switching process and can significantly affect the displacement output of molecular motors.