Construction of cucurbit[n]uril-based supramolecular frameworks via host-guest inclusion and functional properties thereof

Frameworks utilizing cucurbit[n]uril-based chemistry build on the rapid developments in the fields of metal-organic frameworks (MOFs), covalent-organic frameworks (COFs) and supramolecular organic frameworks (SOFs), and as porous materials have found broad applications in heterogeneous catalysis, adsorption and ion exchange as well as other fields. Cucurbit[n]urils (Q[n]s) are suitable as the basic building blocks used for the construction of new Q[n]-based frameworks due to their special structural characteristics including the positive electrostatic potential of the outer surface, the negative portal carbonyl groups and the near neutral potential of the cavity. Herein, summaries of cucurbit[n]uril-based supramolecular frameworks assembled through outer surface interactions and cucurbit[n]uril/metal ion complex-based frameworks are discussed, and this is followed by a review of Q[n]-based frameworks assembled using the structural characteristics associated with the cavity of Q[n]s, i.e. host-guest inclusion chemistry. These assembled Q[n]-based frameworks can be catalogued as (1) simple host-guest inclusion complexes, (2) host-guest inclusion supramolecular polymers, (3) host-guest exclusion complexes or polymers and (4) coordination products of the host-guest inclusion complexes with metal ions. The design and construction of Q[n]-based frameworks via host-guest inclusion chemistry will undoubtedly enrich this new research direction in Q[n] chemistry, and will lead to multiple new applications.