Supramolecular graft copolymers based on 2,7-diamido-1,8-naphthyridines

Supramolecular graft copolymers containing a quadruple hydrogen bond motif in the main chain have been prepared by acyclic diene metathesis (ADMET) polymerization of an alpha,omega-diene monomer containing a 2,7-diamido-1,8-naphthyridine (Napy) unit. During the ADMET polymerization, a supramolecular protection strategy was applied in order to prevent naphthyridine coordination to the ruthenium catalyst. The 2-ureido-4[1H]-pyrimidinone (UPy) derivatives used as protecting groups also allowed for detection of the supramolecular graft copolymer with size exclusion chromatography. Deprotection by simple treatment with a polar solvent afforded free Napy binding sites on the main chain. Reversible grafting of UPy derivatives of various sizes onto the free poly-Napy was demonstrated by diffusion-ordered NMR experiments.