Supramolecular Bracelets and Interlocking Rings Elaborated Through the Interrelationship of Neighboring Chemical Environments of Alkyl-Substitution on Cucurbit[5]uril

The smallest members of the cucurbituril family, cucurbit[5]uril and the alkyl-cucurbit[5]urils, can be used as a building blocks, linked by metal ions to create supramolecular rings. The cavities found at the center of these rings have dimensions between 7 and 19 Å in width and 8.5 Å in depth. The partially substituted alkyl-cucurbit[5]urils present the most interesting supramolecular ring formation. This occurs as a result of selective coordination of metal ions to the carbonyl oxygens of the glycoluril moieties carrying alkyl substitution.