Oligocatenanes made to order

The construction of catenanes, comprised of between two and seven interlocked rings, has been achieved. Two tris-1,5-naphtho-57-crown-15 macrocycles template the formation of cyclobis(paraquat-4,4‘-biphenylene) to give a [3]catenane, which acts as a template for the construction of one and then another cyclobis(paraquat-p-phenylene) to give a [4]- and [5]catenane (Olympiadane). When high pressure was used in these templated syntheses, a [6]- and [7]catenane, as well as a [5]catenane that is topologically isomeric with Olympiadane, were also obtained. X-ray analyses of the [3]-, [5]-, and [7]catenanes reveal an optimum use of electrostatic, π−π stacking, [C−H···π] interactions, and [C−H···O] hydrogen bonds in the organization of the component rings within the molecules. Noteworthy in the [7]catenane structure is the location of four of the PF6- anions within voids present in the 20+ ion. Temperature-dependent 1H NMR spectroscopic studies and electrochemical investigations have revealed the dynamic and redo...