Mechanism of the Stoddart-Heath bistable rotaxane molecular switch.

We use quantum mechanics to characterize the structure and current-voltage performance of the Stoddart-Heath rotaxane-based programmable electronic switch. We find that the current when the ring is on the DNP is 37-58 times the current when the ring is on the TTF, in agreement with experiment (ratio of 10-100). This establishes the basis for iterative experimental-theoretical efforts to optimize systems for molecule-based electronics which we illustrate by predicting the effect of adding a group such as CN to the rotaxane.