Placing Single-Metal Complexes into the Backbone of CO2-Based Polycarbonate Chains, Construction of Nanostructures for Prospective Micellar Catalysis

The copolymerization of CO2 and epoxides in the presence of chain-transfer agents (CTAs) has provided a well-controlled route to polycarbonate polyols. Upon employing dicarboxylic acid CTAs which contain discrete metal-binding sites, it is possible to synthesize polycarbonates with a single-metal complex present in the main chain, either during the copolymerization process or in a postpolymerization procedure. In these ways, the (bipy)Re(CO)(3)Br complex has been incorporated into the polycarbonate backbone. Furthermore, in a one-pot, two-step synthesis, a second epoxide containing a vinyl substituent can be introduced to afford a triblock ABA polycarbonate, where the metal is contained in the B block. Subsequent to the thiol-ene click chemistry of (HSCOOH)-C-boolean AND and deprotonation, the resulting anionic polymer is shown to self-assemble in deionized water to provide rather uniform, spherical micelles. Since this procedure is modular, it is applicable to a wide variety of CTAs containing metal complexes or metal-binding sites, thereby providing a pathway to synthesize a wide range of micellar catalysts for pursuing organometallic transformations in water.