(465a) Organic Photocatalysts for Atom Transfer Radical Polymerization Driven By Visible Light

We report a computational investigation of a new class of organic photocatalysts (OPCs) - Intramolecular Charge Transfer Organic Photocatalysts - for Atom Transfer Radical Polymerization (ATRP) driven by visible light. We used computational chemistry to design and understand OPCs with various desirable properties and then synthesized and characterized these OPCs for ATRP. These photocatalysts are analogous to metal-to-ligand-charge transfer complexes, but involve a photoactive organic moiety rather than a metal center, thus enabling metal-free photocatalyzed reactions and exquisite tuning of the photochemical properties of the catalysts. Organic ATRP photocatalysts have been sought to address this difficult challenge, but have not achieved the precision performance of metal catalysts. We also report experimental results that confirm the predictions of our computational designs and show that in the case of visible light photocatalyzed ATRP they achieve high initiator efficiencies to synthesize polymers with tunable molecular weights and low dispersities. Furthermore, these OPCs can act as long-lived and powerful reducing agents to catalyze a variety of reactions.