Dibenzophenazine and quinoxaline derivatives as novel visible photosensitizers for diaryliodonium salts

Kolay, Merve
This study is focused on the use of visible light in photoinitiated cationic polymerization. Photoinitiated polymerization of oxiranes, vinyl ethers, and other vinyl monomers was achieved. In doing so, (2-(2,3 dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and poly(2,3,5,8-tetra(thiophen-2-yl)quinoxaline) (TTQ), two dibenzo[a,c]phenazine derivatives; 10,13-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)dibenzo[a,c] phenazine (PHED) and 10,13-bis(4-hexylthiophen-2-yl)dibenzo[a,c]phenazine (PHEHT) were utilized as the photosensitizers for diaryliodonium salt photoinitiators. Novel dyes based on the dibenzo[a,c]phenazine and quinoxaline skeleton were shown to be efficient in carrying out the cationic photopolymerizations of a wide variety of epoxide, oxetane, and vinyl monomers at room temperature upon irradiation with long-wavelength UV and visible light. The polymerizations were initiated at room temperature in the presence of diphenyliodonium hexafluorophosphate (Ph2I+PF-6) and monitored by optical pyrometry (OP). The photopolymerization of an epoxide monomer via solar irradiation was also demonstrated.