Diversification of acridinium photocatalysts: Property tuning and reactivity in model reactions

Herein, we describe the discovery and characterization of multiple N -(hetero)aryl, N -benzyl and N -alkyl derivatives of 9-mesityl-3,6-di- tert -butyl-10-phenyl acridinium photocatalyst. The catalytic performances of these catalysts as photo-oxidant or photo-reductant (via in situ generated acridine radical) were compared in three model reactions. We also identified improved catalytic conditions for a previous cyanoarene-catalyzed nucleophilic amination reaction using a synthesized N -cycloheptyl acridinium catalyst (up to 98 % yield). • A library of acridinium photocatalysts was synthesized featuring unexplored N-substitution patterns. • Excited state properties of the catalysts were determined experimentally and investigated computationally. • Three model reactions were evaluated with the photocatalyst library and improved performance was obtained.