Mechanistic Analysis of Molecular Design of Heterocyclic Photoinitiator System

Various Hexaarylbiimidazoles(HABIs) were newly synthesized. The authors studied the photoinitiation efficiency of HABI and hydrogen donor(HD) photoinitiator system and found the efficiency was improved by using electron-negative HABI and electron-releasing HD. Comparing the energy between and HOMO(HD) for a studied system, it was suggested that electron transfer from HD to plays an important role. According to the obtained key reaction step, we have newly designed and synthesized energetically optimized HABIs. The new HABIs were found to have 4 times higher in photoinitiation efficiency.