Effect of Decarboxylation on the Photoinitiation Behavior of Nitrocarbazole-Based Oxime Esters

A series of 50 oxime esters bearing various substituents were designed and synthesized as photoinitiators (48 them never before only B1 B10 reported). Good light absorption properties in the visible range observed for these esters. Some structures exhibited better photoinitiation abilities than diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) upon exposure to a LED@405 nm. Interestingly, PIs with methyl substituent on ester group have performance others. Substituent effects investigated through molecular orbitals calculations, detection CO2, investigation generated free radicals. The results demonstrate that exert major ability via decarboxylation reaction. In addition, chemical mechanism was proposed. 3D printed objects successfully obtained by using most reactive photoinitiator, their thermal initiation behaviors several also studied (dual thermal/photochemical initiator behavior).