A key limitation of the structures presented appears to be their basicity which, although enhanced by the mechanical bond, remains low enough that even in the case of relatively acidic substrate 7, rotaxanes 4a and 4c are inactive in THF and reactions mediated by 4b are slow at reduced temperatures in CDCl3. Indeed, attempts to apply these catalysts to other previously studied anion-π catalysed reactions with less acidic substrates 9b,11e,30 revealed reaction rates that were impractically slow, requiring multiple weeks to observe even trace amounts of product (ESI section S9). Future work will focus on overcoming this limitation by engineering more basic functional groups into the axle of suitable structures while maintaining the π-π stacking interactions that deliver high polarizability and thus strong anion-π interactions for catalysis, as well as developing chiral structures that take advantage of the mechanical bond to deliver enantioselective examples.