Multiturn Hollow Helices: Synthesis and Folding of Long Aromatic Oligoamides.

Aromatic oligoamides adopting helical conformations are synthesized by coupling carboxyl-terminated basic units having two, four, and eight residues to amine-terminated oligomer precursors. Coupling yields show no noticeable reduction with the size of the basic units or the final product. One- and two-dimensional NMR spectroscopy and computational studies demonstrate the reliable helical folding of these oligomers. The X-ray structure of 16mer reveals a compact, multiturn helix having a 9 Å inner pore.