Recent advances in the development of rotaxanes and pseudorotaxanes based on pillar[n]arenes: from construction to application.

Mechanically inter-locked molecules (MIMs) mainly including rotaxanes and pseudorotaxanes have attracted enormous attention for the fabrication of molecular machines, which can be constructed from macrocyclic molecules as the main building blocks through host-guest complexation. Pillar[n]arenes, as a new class of macrocyclic molecules, have a rigid pillar-like shaped architecture with an electron-rich cavity and two fine-tuneable rims. This unique symmetrical and rigid structure, easy modification and excellent properties in host-guest complexation provides pillar[n]arenes with the ability to form various interesting supramolecular systems. Importantly, the π-rich cavity of pillar[n]arenes also endows them with the ability to construct MIMs. This article will provide a comprehensive review of recent advances in pillar[n]arene-based MIMs, primarily focusing on rotaxanes and pseudorotaxanes, and their synthetic methods will be highlighted. In addition, the applications of pillar[n]arene-based MIMs will be summarized while current limitations and perspectives on the construction of pillar[n]arene-based MIMs will also be outlined.