Reducing Molecular Shuttling to a Single Dimension.

An analogy with a cart on a roller coaster partially explains the shuttling motion of macrocycles in peptide rotaxanes. Just above the barrier to shuttling, the macrocycle statistically populates the "track" rather than the low-energy "stations" (see the potential energy curve). The dynamics of the movement is described in terms of a simplified one-dimensional model based on the solution of the relevant quantum-mechanical equation. x=position.