Calixarene Threading by Viologen-Based Axles

The purpose of this chapter is to show the achievement gained over 15 years or so on the use of tris(N-phenylureido) calix[6]arene derivatives as components for oriented pseudorotaxanes and rotaxanes synthesis. A particular emphasis is placed on the exploitation of the chemical and structural information stored in these calix[6]arene derivatives for the unidirectional threading of viologen-based axles that yield oriented pseudorotaxanes. The thermodynamic and kinetic parameters associated with these threading processes will be reported, together with their functioning as prototype of molecular machines under the action of external energy inputs.