Aromatic delta-peptides.

Oligoamides of 8-amino-2-carboxy-quinoline adopt a very stable helical conformation characterized in solution by 1H NMR and in the solid state by single-crystal X-ray diffraction. The helix comprises only 2.5 units per turn, which represents the highest curvature achieved by aromatic oligoamides until now. Monomers possessing alkoxy substituents in position 4 are easily available from 2-nitroaniline and dimethyl acetylenedicarboxylate.