Synthesis of a [2]rotaxane incorporating a Ni(II)-salen moiety: evidence of ring-opening-and-closing protocol

reaction: see text] We have synthesized a 2]rotaxane from a crown-ether-like macrocycle that undergoes ring opening and closing through cleavage and formation of imino bonds of a salen moiety; the self-assembly of this macrocycle and a dumbbell-shaped rodlike component, followed by addition of nickel acetate, afforded, after counterion exchange, a 2]rotaxane that is stabilized through coordination of the Ni ion to the macrocycle's salen moiety.