Synthesis of Metallosupramolecular Networks through Grafting of Azide-Modified Bidentate Ligands

The postpolymerization modification of existing polymers with supramolecular binding motifs represents a versatile pathway toward supramolecular materials. Here, we demonstrate that 1,3-dipolar cycloaddition reactions involving vinyl groups and alkyl azides provide a particularly convenient and effective approach in this context. A bidentate ligand, 6-(1′-methylbenzimidazolyl)-pyridin-3-ol, equipped with an alkylazide handle, was grafted onto poly(butadiene) (PBD) via a solvent-free, melt-based process by simply heating blends of the two components. This approach afforded grafting yields of 63–73%, allows control over the graft density, and avoids the need for solution-based, multistep protocols. The resulting ligand-functionalized PBD was converted into metallosupramolecular networks with various metal salts, affording materials with tunable mechanical properties.