Carbazole‐bound ferrocenium salt as an efficient cationic photoinitiator for epoxy polymerization

The low absorption of cyclopentadienyl‐Fe‐cumene hexafluorophosphate (I‐261) above 300 nm limits its utilization of longer wavelength emission from light sources. We report here the synthesis and photoactivity of a carbazole‐bound ferrocenium salt, cyclopentadienyl‐Fe‐carbazole hexafluorophosphate ([Cp‐Fe‐carbazole]⁺PF₆^?), which efficiently absorbs radiation between 300 and 400 nm. Its photoactivity is higher than that of I‐261 as a cationic photoinitiator. When the photosensitizer benzoyl peroxide (BPO) is employed, [Cp‐Fe‐carbazole]⁺PF₆^? can obviously be sensitized. Two other ferrocenium salts with amine groups, cyclopentadienyl‐Fe‐aniline hexafluorophosphate ([Cp‐Fe‐aniline]⁺PF₆^?) and cyclopentadienyl‐Fe‐p‐methylaniline hexafluorophosphate ([Cp‐Fe‐p‐methylaniline]⁺PF₆^?) were also studied. As photoinitiators, they perform poorly and can not be sensitized by BPO. Copyright © 2005 Society of Chemical Industry