Aniline

pyrrole and their derivatives can initiate photopolymerization of acrylonitrile and form charge transfer complex (CTC) with tetracyanoethylene (TCNE)

their initiation rates and abilities to form CTC are related to the twist angle between the n orbit of nitrogen atom and the p orbit of benzene ring or pyrrole ring. The greater the twist angle

the lower the polymerization rate and the more difficult forming CTC. These results are explained with the relation between n-p conjugation and the twist angle.