Selective and Efficient Upcycling of Polyesters from Waste Plastic Blends Enabled by a Rationally Designed Manganese Pincer Catalyst

Abstract

Herein, we report a new class of earth-abundant pincer manganese catalysts that not only enable the efficient conversion of single-component post-consumer polyesters with a turnover number (TON) of up to 5300, but more importantly, allow the selective upcycling of polyesters from waste plastic blends (e.g., nylon, PA; polyethylene, PE; polyurethane, PU; polyvinyl chloride, PVC; cotton) or contaminants such as pigment, aluminum, or glass into highly valuable oxygenated products under mild conditions. Detailed mechanistic studies combined with DFT calculations revealed that the exceptional efficiency of this protocol is due to the use of rationally designed quinaldine-based PNN^H-type Mn complexes with an extended π-system and an N−H moiety on the side arm to simultaneously enhance the stability and reactivity of the catalyst. In addition, the incorporation of dual metal-ligand cooperation (MLC) relay catalysis more effectively facilitates the key steps of this transformation, including H₂ activation and hydrogen bond-assisted hydride transfer.