A reverse donor-acceptor bistable [2]Catenane

Abstract

A [2]catenane, composed of a pi-electron-rich bis-1,5-dioxynaphthalene[38]crown10 (BDNP38C10) ring, mechanically interlocked with a large macrocycle containing two disubstituted tetraarylmethane "speed bumps" and two different pi-electron-deficient units-namely, naphthalene dimide (Npl) and bipyridinium (Blpy(2+)) units-has been synthesized from a [2]rotaxane, containing the former recognition unit, after performing two sequential Cu(l)-catalyzed azide-alkyne cycloadditions with a linker containing the latter recognition unit. The product, which exists as a single co-conformer, wherein the BDNP38C10 ring encircles the Npl unit, undergoes equilibration to give approximately equal amounts of the other co-conformer in which the BDNP38C10 ring encircles the Blpy(2+) unit.