Description
Supramolecular chemistry studies the phenomenon of self-assembly and emergent properties of monomers into larger structures and complexes, such as capsules. These supramolecular capsules are held together by non-covalent interactions such as hydrogen bonding and metal-ligand coordination, which are produced by the distinct moieties and functional groups of each individual molecular unit within the structure analogous to how the interactions of the various amino acid side chains govern the folding of a protein. One of the emergent and distinct properties of supramolecular complexes is the ability to encapsulate guest molecules. Furthermore, these capsules can form a kinetically-stable host-guest complex. The purpose of our research is to functionalize such kinetically-stable supramolecular structures with polymers for future applications in materials science. According to our hypothesis, polymer-appended metal-ligand and hydrogen-bonded capsules, such as the M4L6 tetrahedron and the pyrogallol[4]arene hexamer, respectively, will be mechanically responsive and offer new properties in materials science. The first step in reaching that goal is to synthesize a polymer-appended M4L6 tetrahedron and pyrogallol[4]arene hexamer and in doing so, we are currently developing novel synthetic routes to functionalize the capsules. The strategy we have taken for the polymer-appended M4L6 synthesis involves a series of amide coupling reactions to make a ligand with a terminal alkyne in order to perform a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction (also known as “click chemistry”) with a polyethylene glycol azide polymer. Click chemistry and cross metathesis reactions are being explored to append an alkyne-functionalized polymer to an azide-monofunctionalized pyrogallol[4]arene hexamer. Further optimizations need to be made in the future to finalize the synthesis of the polymer-appended metal-ligand and hydrogen-bonded capsules.
