Structure/reactivity/photoinitiation ability relationships in novel benzo pyrazolo (or imidazo) isoquinolinone derivatives upon visible light LEDs

International audienceIsoquinolinone derivatives bearing amino- or nitro- substituent (IQNs) have been synthesized as photoinitiators and combined with various additives (i.e., iodonium salt, N-vinylcarbazole, amine or 2,4,6-tris(trichloromethyl)−1,3,5-triazine) to initiate ring-opening cationic polymerizations (CP) or free radical polymerizations under exposure to visible LEDs (e.g., LEDs at 405 nm or 455 nm, or cold white LED) or a halogen lamp. Compared to the well-known camphorquinone-based systems, the novel IQNs-based combinations employed here demonstrate higher efficiencies for the CP of epoxides. The photochemically generated reactive species (i.e., cations and radicals) from the IQNs-based systems have been investigated by steady state photolysis, cyclic voltammetry, fluorescence, laser flash photolysis, and electron spin resonance spin trapping techniques. The structure/reactivity/photoinitiating ability relationships of IQNs-based combinations are also discussed; the crucial role of the excited state lifetimes of the photoinitiators to ensure efficient quenching by additives is clearly underline