Reactive Species from Solution by Reversible Encapsulation

Isolation of the Reactive Species from Solution by Reversible Encapsulation 

FIGURE 16 Top Molecular structures of cucurbit[6]uril and products and reactants of 1,3-dipolar cycloaddition. Bottom Side and top views of the CAChe transition state structure for the formation of the 1,4-triazole included in the cucurbit[6]uril (55). 

Moreover, solvent reorganization energies, which are required for fhe reaction to occur in a bulk solvent, are not needed in the presence of fhe cucurbit[6]uril. This mechanism probably also contributes to the large rate enhancement. The inclusion of fhe reacting groups into the molecular reaction vessel eliminates any retardation of the reaction by the solvent environment. 

To completely surround a molecule with a s)mthetic receptor is a daunting task and constitutes the ultimate goal of molecular recognition 

FIGURE 18 Top Molecular structure of Rebek s capsule (59) for the acceleration of a 1,3-dipolar cycloaddition between phenylacetylene and phenyl azide. Bottom CAChe-minimized structure of the ternary complex. Symmetrically loaded capsules are also found in solution. (See Color Insert in the back of this book.) 

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