STRUCTURE-PROPERTY DESIGN PRINCIPLES FOR CORE SUBSTITUTED PHENAZINE PHOTOREDOX CATALYSTS IN ORGANOCATALYZED ATOM TRANSFER RADICAL POLYMERIZATION

Abstract

The relationship between molecular structure and photophysical properties is central to the design of organic chromophores that efficiently harness the energy of light for chemical applications. Phenazine photoredox catalysts (PCs) have emerged as a class of highly reducing, visible-light absorbing molecules with multiple sites for structural modification to tune their photophysical properties. These catalysts have demonstrated strong performance in controlled radical polymerizations, particularly organocatalyzed atom transfer radical polymerization (O-ATRP), where catalyst structure directly influences PC properties and polymerization control. Within the phenazine family, however, triplet excited state properties are often overlooked, especially in alkyl core substituted phenazines generated from radical addition side reactivity that can occur during O-ATRP. This dissertation investigates the structure-property-performance relationships of phenazine photoredox catalysts synthesized via radical addition with common radical initiators in O-ATRP, with particular emphasis on triplet excited state properties and the interplay between the singlet and triplet excited states. Through rational phenazine design, we elucidate how specific structural modifications influence PC excited state redox and photophysical properties to enable improved catalytic performance in controlled radical polymerizations.