Photoinitiators with β-Phenylogous Cleavage: An Evaluation of Reaction Mechanisms and Performance

Abstract

Bimolecular photoinitiators based on benzophenone and N-phenylglycine ideally overcome limitations of classical two-component systems, such as the possibility of deactivation by a back electron transfer or the solvent cage effect. Furthermore, if they are covalently linked, loss of reactivity by diffusion limitation could be reduced. Here we show that such an initiator displays unusually high photoreactivity. This is established by photo-DSC experiments and mechanistic investigations based on laser flash photolysis, TR-EPR, and photo-CIDNP. The β-phenylogous scission of the C–N bond is highly efficient and leads to the production of reactive initiating radicals at a short time scale.