Strain-Controlled Synthesis of [n]Catenanes from Dipyrromethane-Stoppered Rotaxanes

The synthesis of rotaxanes featuring two dipyrromethane stoppers, which differ in thread length and rigidity, is presented. The condensation of the precursor rotaxanes with acetone was found to be influenced by the axle’s structural facets. As a result, the calix[4]phyrin-based macrocyclization strategy produced [2]-, [3]-, and [4]catenanes, depending on the specific structure of the rotaxane substrate.