[3]Rotaxanes and [3]pseudorotaxanes with a rigid two-bidentate chelate axle threaded through two coordinating rings

Abstract

New [3]rotaxanes and [3]pseudorotaxanes have been synthesised using the “gathering and threading” effect of copper(I). By using click chemistry as the “stoppering” reaction, a good yield of the [3]rotaxane was obtained, either as a dicopper complex or as a metal-free compound after demetallation. The axle contains a central rigid aromatic block incorporating two bidentate chelates, and the threaded macrocycles are 30-membered rings. A model dicopper(I) [3]pseudorotaxane whose axle was end-functionalised by triisopropylsilyl groups could be crystallised and studied by X-ray diffraction. A particularly attractive structure was obtained showing a “slanted” geometry for the two rings and the axle, the two 1,10-phenanthroline units of the rings being almost parallel to one another but their respective mean planes being more than 7 Å apart.