Assembled columnar structures from bis-urea macrocycles

Presented is a review of our research on using macrocyclic bis-ureas as supramolecular building blocks. These macrocycles predictably self-assemble into columnar structures via strong urea-urea hydrogen bonds and pi-stacking interactions. We developed a facile synthetic route to these macrocyclic ureas, confirmed their self-assembly pattern, and are now assessing their potential as a supramolecular building block. A series of bis-urea macrocycles were synthesized and assembled to verify the fidelity of their self-assembly motifs. Ultimately, a large phenylether bis-urea macrocycle was synthesized that formed tubular assemblies containing a guest accessible channel. We have characterized the structure of the assembled nanotubes by NMR and X-ray crystallography and evaluated this new porous solid with respect to its binding properties and specificity. This porous self-assembled material is thermally and chemically stable and can reversibly bind and exchange a variety of guest molecules.