Macrocycles containing azo groups: recognition, assembly and application

Macrocyclic compounds play an important role in supramolecular chemistry accounting for their unique recognition and self-assembly properties and potential applications in biomedicine and material science. Azo compounds display promising capability in fields of molecular switches, polymers, smart materials and molecular machines because of their photoactive and electroactive properties. Introducing azo groups into macrocycles gives them signal moieties, additional recognition sites, photo-responsive properties, and so on. Herein, we comprehensively review the structures of azo-containing macrocyclic compounds reported up to now. Then we describe representative works on azo macrocycles with their molecular recognition, self-assembly and application emphasized.