Robust helix formation in a new family of oligoureas based on a constrained bicyclic building block.

BAC for more: a constrained bicyclic building block with urea linkages is an efficient combination for the formation of a highly rigid helical system. This type of bicyclic amino carbamoyl (BAC) foldamer was studied both in solution and in the solid state. A robust H-bond (dotted line) network was found between the carbonyl oxygen atoms (red) and the amino groups (dark blue) within the helix.