New Strategies for the Design of Inclusion Compounds with Cucurbituril Hosts

This chapter encompasses most of the very recent studies that have utilized host-guest complexations of cucurbit[n]uril (CBn) in constructing various stimuli-responsive supramolecular nanostructures such as supramolecular metal nanoparticles, beads, colloids, hydrogels, micelles, colloidosomes, and polymers. It is concluded that certain unique host-guest properties of CBn were considered to specifically construct stimuli-responsive nanostructured materials. The high and selective binding affinity to adamantylamine (ADA) and ferrocene derivatives has facilitated guest competition-responsive systems. Also, the ability of CB8 to form a selective ternary complex with viologen derivatives and other guest molecules has led to a redox-controlled switching upon the oxidation and reduction of the viologen unit. Furthermore, the suitable cavity of CB7 that distinguishes cis and trans configuration of azo dyes has permitted the preparation of light-controlled switching systems. In some occasions, the higher affinity toward cationic guests over neutral molecules has established pH-controlled systems. On the top of that, the negative carbonyl portals of CBn have stabilized the metal nanoparticles during the formation of hybrid organic-inorganic structures. The chapter also highlights the real applications of these CBn-based nanostructures such as fabrication of self-healing materials, in vitro therapeutics, peptide and protein isolations, and cellular transportation. The potential applications in cancer therapy and electronic materials are also noted.