Amphiphilic Polycarbonate Micellar Rhenium Catalysts for Efficient Photocatalytic CO Reduction in Aqueous Media.

A triblock amphiphilic polymer derived from the copolymerization of CO and epoxides containing a bipyridine rhenium complex in its backbone is shown to effectively catalyze the visible-light-driven reduction of CO to CO. This polymer provides uniformly spherical micelles in aqueous solution, where the metal catalyst is sequestered in the hydrophobic portion of the nanostructured micelle. CO to CO reduction occurs in an efficient visible-light-driven process in aqueous media with turnover numbers up to 110 (>99 % selectivity) in the absence of a photosensitizer, which is a 37-fold enhancement over the corresponding molecular rhenium catalyst in organic solvent. Notably, the amphiphilic polycarbonate micelle rhenium catalyst suppresses H generation, presumably by preventing deactivation of the active catalytic center by water.