[2]Pseudorotaxanes Based on the Recognition of Cryptands to Vinylogous Viologens

Host–guest complexation between two crown ether-based cryptands and two vinylogous viologens has been studied. Formation of [2]pseudorotaxanes from a dibenzo-24-crown-8-based cryptand and these vinylogous viologens can be reversibly controlled by adding and removing potassium cation in acetone. Furthermore, the complexation between a bis(m-phenylene)-32-crown-10-based cryptand and a vinylogous viologen exhibits a high association constant, 1.18 × 106 M–1 in acetone, and leads to the formation of a supramolecular poly[2]pseudorotaxane in the solid state.