Aromatic oligoamide macrocycles with a backbone of reduced constraint.

Oligoamide macrocycles with a backbone partially constrained by hydrogen bonds have been prepared. These macrocycles, carrying multiple H-bonding side chains, underwent strong aggregation in solution and form long fibers in the solid state. In contrast to the strong and specific complexation of the guanidinium ion by analogous macrocycles with fully H-bond-constrained backbones, these macrocycles failed to recognize the same cation, indicating that reducing backbone constraint has led to a drastic change in their cavity.