Assembling features of calixarene-based amphiphiles and supra-amphiphiles

Macrocyclic amphiphiles as an emerging family of artificial amphiphiles have gained considerable attention in recent years on account of their fascinating recognition and assembly properties. Benefiting from a preorganized framework, facile modification and host-guest recognition ability, calixarenes have been widely used to fabricate self-assemblies of both amphiphiles and supra-amphiphiles. In this review, we organized hundreds of reported amphiphilic calixarenes based on their structures and systematically summarized assembling features of calixarene-based amphiphiles and supra-amphiphiles. For amphiphilic calixarenes, the size and conformation of skeletons significantly affect their assembly behaviors, such as lower critical aggregation concentration (CAC) and more diverse morphology than conventional amphiphiles. Besides, we also focus on emerging topics like uniformity, compactness, and kinetic properties of calixarene aggregation. For supra-amphiphiles, the binding affinities of calixarenes endow them with the ability to induce guest assembly. In addition, complexation of guests also improves amphiphilic calixarene aggregation. The obtained assemblies not only possess the advantages of low CAC and compact packing, but also respond to various stimuli. Finally, we pointed out several research topics of calixarene-based amphiphiles and supra-amphiphiles to be further developed in the future, such as the relationship between molecular structures and assembly properties, crosslinking, co-assembly, and utilization of cavities. We hope this review could be a guidance for studying amphiphilic assemblies based on calixarenes and other macrocyclic compounds.