Zhong, YongliangFeng, QuanyouWang, XiaoqianYang, LeiKorovich, Andrew G.Madsen, Louis A.Tong, Rong2021-04-222021-04-222021-03-142041-6520http://hdl.handle.net/10919/103079Photoredox ring-opening polymerization of O-carboxyanhydrides allows for the synthesis of polyesters with precisely controlled molecular weights, molecular weight distributions, and tacticities. While powerful, obviating the use of precious metal-based photocatalysts would be attractive from the perspective of simplifying the protocol. Herein, we report the Co and Zn catalysts that are activated by external light to mediate efficient ring-opening polymerization of O-carboxyanhydrides, without the use of exogenous precious metal-based photocatalysts. Our methods allow for the synthesis of isotactic polyesters with high molecular weights (>200 kDa) and narrow molecular weight distributions (M-w/M-n < 1.1). Mechanistic studies indicate that light activates the oxidative status of a Co-III intermediate that is generated from the regioselective ring-opening of the O-carboxyanhydride. We also demonstrate that the use of Zn or Hf complexes together with Co can allow for stereoselective photoredox ring-opening polymerizations of multiple racemic O-carboxyanhydrides to synthesize syndiotactic and stereoblock copolymers, which vary widely in their glass transition temperatures.application/pdfenCreative Commons Attribution-NonCommercial 4.0 InternationalArticle - Refereedhttps://doi.org/10.1039/d0sc05550f12102041-6539