Through the study of structure-property relationships using a combination of experimental and computational analyses, several phenoxazine derivatives have been developed as visible light-absorbing, organic photoredox catalysts with strongly reducing excited state reduction potentials. Computational modeling of the photoexcitation of N-aryl and core modified phenoxazines was performed to guide the design of PCs with absorption profiles in the visible regime. Characterization of the excited states of both core and non-core modified N-aryl phenoxazines revealed their ability to access charge transfer excited states. Modification of the core of phenoxazine derivatives with electron donating and electron withdrawing substituents altered the triplet energies, excited state reduction potentials, and oxidation potentials of the phenoxazine derivatives. These PCs were employed in the organocatalyzed atom transfer radical polymerization (O-ATRP) for the synthesis of poly(methyl methacrylate) (PMMA) using white-light irradiation. All of the derivatives used as O-ATRP PCs were able to catalyze the polymerization in a controlled fashion to synthesize PMMA with dispersity typically less than 1.3 with many of the derivatives achieving initiator efficiencies ≥ 95 %.

Structure-property relationships for tailoring phenoxazines as reducing photoredox catalysts

255th National Meeting (2018)

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