Catalysis in the self-assembly of [2]rotaxanes and [2]pseudorotaxanes. Effect of the length of polyethereal side arms and terminal stoppers.

The template effects exerted by compounds 3, 5, 6, and 8 in the ring closure reaction of the trication 1(3+) to yield the [2]pseudorotaxanes 15(4+) and 17(4+) and the [2]rotaxanes 18(4+) and 20(4+) have been quantitatively evaluated in acetonitrile at 62 degrees C by UV/vis spectrophotometry. The rate of ring closure of the trication 1(3+) largely increases in the presence of the templates up to a maximum of ca. 200 times in the case of 5 at a concentration of ca.