Synthesis and Structure-Activity Relationship of N-Substituted Carbazole Oxime Ester Photoinitiators

Four N-phenyl substituted carbazole oxime ester photoinitiators were synthesized and their structure-activity relationship were systematically investigated. These photoinitiators have a broad absorption in the range of 300-400 nm and the tail absorption extends above 400 nm. Under 405 nm LED light irradiation, the oxime esters undergo photodecarboxylation and generate active free radicals to induce polymerization of acrylates. The tert-butyl substituted aldehyde-oxime ester Ph-N-CZ-2 with terminal methyl group exhibit the best photoinitiation performance among the four N-substituted carbazole oxime esters.