A Peptoid Square Helix via Synergistic Control of Backbone Dihedral Angles.

The continued expansion of the fields of macromolecular chemistry and nanoscience has motivated the development of new secondary structures that can serve as architectural elements of innovative materials, molecular machines, biological probes, and even commercial medicines. Synthetic foldamers are particularly attractive systems for developing such elements because they are specifically designed to facilitate synthetic manipulation and functional diversity. However, relatively few predictive design principles exist that permit both rational and modular control of foldamer secondary structure, while maintaining the capacity for facile diversification of displayed functionality.