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The creation of self-assembling microscale architectures that possess new and useful physical properties remains a significant challenge. Herein we report that an 11-helical foldamer self-assembles in a controlled manner to form a series of 3D foldectures with unusual three-fold symmetrical shapes that are distinct from those generated from 12-helical foldamers. The foldamer packing motif was revealed by powder X-ray diffraction technique, and provides an important link between the molecular-level symmetry and the microscale morphologies. The utility of foldectures with hollow interiors as robust and well-defined supramolecular hosts was demonstrated for inorganic, organic, and even protein guests. This work will pave the way for the design of functional foldectures with greater 3D shape diversity and for the development of biocompatible delivery vehicles and containment vessels., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Molecular self-assembly is the spontaneous association of molecules into structured aggregates by which nature builds complex functional systems. While numerous examples have focused on 2D self-assembly to understand the underlying mechanism and mimic this process to create artificial nano- and microstructures, limited progress has been made toward 3D self-assembly on the molecular level. Here we show that a helical β-peptide foldamer, an artificial protein fragment, with well-defined secondary structure self-assembles to form an unprecedented 3D molecular architecture with a molar tooth shape in a controlled manner in aqueous solution. Powder X-ray diffraction analysis, combined with global optimization and Rietveld refinement, allowed us to propose its molecular arrangement. We found that four individual left-handed helical monomers constitute a right-handed superhelix in a unit cell of the assembly, similar to that found in the supercoiled structure of collagen.