(A and B) Complementary [G3NO3]2+ (yellow) and HSPB6– (green) tiles, with their corresponding edge lengths, defined by the distance spanned by neighboring guanidinium and sulfonate ions, respectively. (C) Schematic representation of an unfolded q-TO based on the complementary [G3NO3]2+ (yellow) and HSPB6– (green) tiles, illustrating the edge-shared N-H•••O-S hydrogen bonds. (D) The q-TO. The open squares in (C) and (D) correspond to the openings on the surface of the q-TO that enable the formation of <100> channels between adjacent q-TOs in the solid state.

Self assembly of multiple components into well-defined and predictable structures is one of the great challenges of chemistry.  In a paper published in Science, researchers from New York University and the University of Milano-Bicocca report the creation, through self assembly, of a supramolecular cage assembled from 20 ions of 3 different species through 72 hydrogen bonds.  The cage, with an internal volume of 2200 cubic angstroms, is of the form of a truncated octahedron, one of the Archimedean polyhedra.  Said octahedron serves as the composite building unit of a body-centred cubic framework with the ability to encapsulate a wide range of differently charged species, including organic molecules, transition metal complexes, and “ship-in-a-bottle” nanoclusters.  The crystalline structure was ascertained using crystal diffraction at the ChemMatCARS 15-IDB Crystallography station, at the APS.


Yuzhou Liu, Chunhua Hu, Angiolina Comotti, Michael D. Ward
Supramolecular Archimedean Cages Assembled with 72 Hydrogen Bonds
Science 333 (6041), 436-440 (2011).  Author affiliations:  1New York University;  2University of Milano-Bicocca.