Selectivity algorithm for the formation of two cryptand/paraquat catenanes.

Two [2]catenanes based on two different cryptand hosts, a dibenzo-24-crown-8-based cryptand and a bis(m-phenylene)-26-crown-8-based cryptand, have been synthesized and characterized. These two cryptand hosts only have a minor difference in chemical structure. However, this minor structural difference leads to big differences in the configurations and packing modes of the resulting catenanes. In addition, from the crystal structures of the two catenanes, we found that the cyclophane guest seems to have a selectivity algorithm and chooses the larger-size rings to go through and interlock with.