The natural world uses hydrogen bonding and metal-ligand interactions ubiquitously to hold proteins together into higher order structures. This approach is rarely used in synthetic chemistry and has never been used to generate discrete host-guest complexes. The specific goals for this project are to use a symmetry-based approach, similar to that employed to make metal-ligand supramolecular clusters, to assemble nanoscale cavity-containing clusters using both hydrogen bonding and metal-ligand interactions to hold the assembly together. Nature appreciates the power of using metal coordination and hydrogen bonding within one bio-molecule, this proposal seeks to mimic this motif on a preparative synthetic scale by coupling a well-known metal chelating module to a self-complementary hydrogen bonding module within a single molecule. Simultaneous coordination of the chelator to a metal ion and formation of the self-complementary hydrogen bonds will result in the self-assembly of a high-symmetry, cavity-containing, dimeric assembly composed of 12 metal-ligand bonds and 12 hydrogen bonds. These hybrid nanoscale assemblies will be studied to understand: (1) how metal coordination in a hybrid molecule-within-molecule complex will affect the affinity of guest inclusion, (2) how the """"""""folding"""""""" or overall topology of the supramolecular complex is influenced by metal coordination and/or hydrogen bonding, and (3) whether there is a cooperative or synergistic effect between metal-coordination and hydrogen bonding when assembling such synthetic analogues. In addition, successful synthesis of a hybrid supramolecular complex would provide a proof of principle to the proposed design strategy and allow synthesis of new clusters to exploit the host-guest chemistry generated by these nanoscale complexes.
