Synthesis of tripodal [2]rotaxanes: high concentration principle

Symmetrical and non-symmetrical tripodal [2]rotaxanes (1) incorporating 1,1-disubstituted-4,4-bipyridinium cations (2) and 34-crown-10 (3) have been prepared directly from 4,4-bipyridine or from monocationic intermediates in high yields at room temperature and atmospheric pressure under conditions that permit the use of high reagent concentrations (0.1–0.2 M, 150–200 g l–1).