In the field of supramolecular chemistry, the structure and properties of the receptor (host) dictate its binding to guest molecules. Approaches to chemically modifying receptors are very attractive because they can be used to tailor the binding affinity and selectivity to different guest molecules and under different conditions. The vast majority of macrocyclic receptors (e.g., cucurbiturils, cyclodextrins, crown ethers, and calixarenes), however, are difficult to modify due to their repeating structures and/or undesirable solubility properties. We have circumvented this problem using the two-guest binding property of the macrocyclic cucurbit[8]uril (Q8) to modify the physical properties of the receptor without performing any synthetic modification of the macrocycle itself.  Q8 is unique in that it can bind two different guest molecules simultaneously. Threading a viologen derivative (as the first guest) through the Q8 receptor and stoppering produces a Q8-rotaxane that can bind a second guest as an inclusion complex. The resulting rotaxane is a new receptor with intrinsic solubility and binding properties that derive both from Q8 and from the threaded and stoppered first guest. The synthesis and characterization of Q8-rotaxanes and their applications will be described.

Synthesis and characterization of mechanically interlocked cucurbit[n]uril receptors

243rd National Meeting (2012)

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