Building β-Peptide H10/12 Foldamer Helices with Six-Membered Cyclic Side-Chains: Fine-Tuning of Folding and Self-Assembly

The ability of the β-peptidic H10/12 helix to tolerate side-chains containing six-membered alicyclic rings was studied. cis-2-Aminocyclohex-3-ene carboxylic acid (cis-ACHEC) residues afforded H10/12 helix formation with alternating backbone configuration. Conformational polymorphism was observed for the alternating cis-ACHC hexamer, where chemical exchange takes place between the major left-handed H10/12 helix and a minor folded conformation. The hydrophobically driven self-assembly was achieved for the cis-ACHC-containing helix which was observed as vesicles ~100 nm in diameter.