Coumarin-containing pillar[5]arenes as multifunctional liquid crystal macrocycles

Liquid crystal macrocycles (LCMs) combine the unique properties of liquid crystals with those associated with macrocyclic compounds—shape persistence and the capability of hosting small molecules. Herein, we investigate the grafting of coumarin-containing promesogenic moieties to pillar[5]arene as a strategy to obtain multifunctional LCMs. Pillar[5]arenes containing 10 and 30 coumarin units are glassy materials with nematic mesomorphism. Moreover, the coumarin moieties afford the pillar[5]arene derivatives with enhanced film-forming and photoresponsive properties. Photodimerization of the coumarin moieties results in cross-linked polymer networks, which can be used as alignment layers. Therefore, liquid-crystal coumarin-containing pillar[5]arenes represent a significant addition to the family of LCMs and may become useful for the development of engineered, hierarchical structures and materials.