Researchers at Northwestern University, USA, and KAIST, South Korea, looked at the properties of a synthetic, cylindrical macrocycle composed of five hydroquinone rings linked through its para positions by methylene bridges. They modified one such monofunctionalised pillar[5]arene by adding a viologen side-chain and watched its self-complexation in dilute dichloromethane.

At low concentration, supramolecular daisy-chain polymers form, but these become gels at higher concentration. The team is currently investigating the switching behavior of this material.

• A self-complexing and self-assembling pillar[5]arene,
  N. L. Strutt, H. Zhang, M. A. Giesener, J. Lei, J. F. Stoddart,
  Chem. Commun. 2011.
  DOI: 10.1039/C2CC16030G