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.