Relaxing Toward Rotaxanes

Abstract

Traditional approaches to the chemical synthesis of complex molecular topologies, such as knots and interlocked rings, have focused on reducing kinetic barriers. More recently, an alternative approach has relied on the reversible assembly of comparatively simple building blocks that relax eventually into the desired topological conformation because it is the most favorable thermodynamic arrangement. Northrop et al. apply this second strategy to the preparation of [4]pseudorotaxanes, in which a Y-shaped core bears a ring on each of its three axes, and the rings in turn are linked to one another through either one or two central capping groups parallel to the planar core.