Helical chirality in donor-acceptor catenanes

A [2]catenane in which the macrocyclic polyether, bisparaphenylene[34]crown-10, is interlocked with the tetracationic cyclophane, cyclobis(paraquat-p-phenylene), is shown by dynamic 1H NMR spectroscopy, using (i) neutral and (ii) anionic chiral shift reagents (CSRs), to exist at low temperatures (197 K) in acetone-d6 solutions as 1:1 and 2:1 mixtures of diastereoisomeric complexes and salts, respectively, as a consequence of the helical chirality associated with the [2]catenane interacting with the CSRs.