Crescent oligoamides: From acyclic "macrocycles" to folding nanotubes

Oligoarylamides whose backbones are rigidified by intramolecular hydrogen b onds (H-bonds) are found to adopt well-defined conformations in both soluti on and solid state. Depending on the length of their backbones, these foldi ng oligoamides are crescents, broken macrocycles, or helices. A large (appr oximate to 10 Angstrom) interior cavity is associated with the "macrocycles " and helices. The folded conformations are independent of chain length and are found in both nonpolar and polar solvents. This strategy is being exte nded to the construction of folding acyclic "macrocycles" and nanotubes wit h larger tubular cavities.