The control of translational isomerism in catenated structures

The self-assembly in 50% yield of a [2]-catenane, comprised of 1,5-naph- tho-para-phenylene-36-crown-10 and the cyclobis(paraquat-p-phenylene) tetracation, is described. This interesting compound has been characte- rized electrochemically and photochemically, as well as by FABMS and NMR spectroscopy, and found to exist in solution as a mixture of two tran- slational isomers depending on whether the hydroquinol ring or the 1,5- dioxynaphthalene unit of the crown ether occupies the central cavity of the tetracationic cyclophane. The equilibrium ratio of these two isomers is shown to be highly dependent on the polarity of the solvent in which the catenane is dissolved