Hydrogen Bonded Arylamide Foldamers: from Conformational Control to Functional Evolution

Hydrogen bonded aryl amide and hydrazide foldamers may adopt folded or helical, zigzag, straight or other extended conformations, depending on the positions of the amides and hydrogen bonding acceptors on the aromatic rings. Because of the relatively high strength of hydrogen bonding and the intrinsic planarity of the arylamide units, this family of amide oligomers usually possesses highly predictable conformations. The frameworks themselves can be conveniently constructed via simple amide coupling reactions, while discrete functional groups can be introduced to the frameworks or appended side chains at required positions. Thus, in the past few years, we have focused on their applications in designing new molecular tweezers, for generating well-defined and functional supramolecular systems, including organogels, vesicles and liquid crystals, and for directing the formation of complicated macrocyclic systems. More recently, we have found that hydrogen bonding-driven folded segments can also be incorporated into polymers to reversibly tune their mechanical property through the breaking and recovering of the intramolecular hydrogen bonds. This Mini Account summarizes our recent efforts along this line.