Cucurbiturils
Over the years supramolecular chemists have designed, synthesized, and evaluated the recognition properties of a wide variety of non-natural receptors. These include cyclodextrins, calixarenes, crown ethers, and many others that display remarkable affinity and selectivity. Although cyclodextrins (CDs) remain the receptor of choice for industrial applications on account of their commercial availability and low cost, several limitations arising from their low affinity and low selectivity exists. To this end, a new class of supramolecular host molecules, cucurbit[n]uril (CB[n]), emerged as a potential hosts. The association constants (Ka) of their host-guest complexes are typically several orders of magnitude higher than that of CDs in aqueous systems. One of the most interesting feature of this class of hosts is the ability to bind two guest molecules inside the hydrophobic cavity in case of CB[8]. A typical guest pair is the methylviologen and naphthalene moiety. Such host-guest binding model opened up the possibility to design and construct diversified stimuli sensitive conjugated architectures. We are particularly interested to exploit such unique host-guest interactions to prepare dynamic aggregated soft-materials for sensors and drug delivery.