Benzylidene ketones as visible light radical photoinitiator: The effects of electron-donating group and co-initiator

The effect of electron donating group and different co-initiator on the benzylidene ketone’s photoinitiation ability were investigated. [Display omitted] •Benzylidene ketones (BK) bearing different electron donating group were synthesized.•Photophysical and electrochemical properties of BK were investigated.•Effect of electron donating group and co-initiator on photoinitiation efficiency were studied. Benzylidene ketones (BK) are promising visible photoinitiator due to their facile synthesis and photochemical hydrogen atom transfer (HAT) reaction between tertiary amines. However, the effect of electron donating (ED) groups on their photophysical, electrochemical properties, and initiation efficiency were not fully disclosed. Moreover, it is not clear which co-initiator is suitable for BK. In this work, four benzylidene ketones bearing hydrogen (C3PH), methoxy (C3PO), methylthio (C3PS), and dimethylamine (C3PN) substitution were synthesized and characterized. BK’s maximum light absorption wavelengths increase following the order of C3PH