Nitroxide-Mediated Controlled Free Radical Polymerization of the Chelate Monomer 4‑Styryl-tris(2-pyridyl)borate (StTpyb) and Supramolecular Assembly via Metal Complexation

The reaction of 4-(dibromoboryl)­styrene with 2-pyridylmagnesium chloride resulted in the formation of 4-styryl-tris­(2-pyridyl)­borate free acid (StTypb), a new polymerizable nonpyrazolyl “scorpionate” ligand. StTypb did not undergo self-initiated polymerization under ambient conditions and proved to slowly polymerize through standard radical polymerization at 90 °C. Nitroxide-mediated polymerization (NMP) of StTypb at 135 °C proceeded with good control, resulting in a polymer of Mn = 27400 and PDI = 1.21. The TEMPO-terminated homopolymer successfully initiated the polymerization of styrene, generating an amphiphilic block copolymer with DPn of 1200 and 78 for the PS and the StTypb block, respectively. A similar block copolymer with DPn of 29 and 20 for the PS and the StTypb block respectively was obtained in a reverse polymerization procedure from a PS macroinitiator. The self-assembly of these block copolymers was examined in selective solvents and preliminary metal complexation studies were performed.