Regulation of Macrocycle Shuttling Rates in [2]Rotaxanes by Amino-Acid Speed Bumps in Organic–Aqueous Solvent Mixtures

Article abstract of DOI:10.1002/ejoc.202000997

A homologous series of two-station [2]rotaxanes incorporating amino-acid units in the molecular thread has been developed. The degenerate [2]rotaxanes exhibit amino-acid specific shuttling rates between two fumaric stations related to the steric factor associated to the amino-acid side chain, as demonstrated by variable-temperature ¹H NMR spectroscopy and exchange spectroscopy (EXSY). This allows tuning of the macrocycle shuttling rate over 4 orders of magnitude, which has a relatively small solvent dependency.