Pillar[6]arenes:From preparation,host-guest property to self-assembly and applications

Pillar[n]arenes primarily comprise pillar[5]arenes and pillar[6]arenes,which belong to the new class of supramolecular macrocyclic hosts.Pillar[n]arenes have aroused wide attention because of their highly rigid and symmetrical architectures,controllable cavity size,and wide applications in a wide variety of areas.Although pillar[6]arene is difficult to synthesize,numerous studies have been conducted on it.In this review,the strategies to synthesize and functionalize pillar[6]arenes are investigated systematically.In addition,their host-guest properties in organic solvents and in aqueous solution are described.More-over,pillar[6]arenes applied in different fields(e.g.,molecular recognition,drug release,cancer therapy,and gas separation)are clarified.Hopefully,this study is capable of arousing more attention from increas-ing scientists to study large-cavity pillar[n]arenes.