Expanded dipyrrins with electron-withdrawing substituents: broad range of absorption in the visible region

Reaction of meso-aryl-substituted dipyrromethanes with tetracyanoethylene led to generation of a mono-tricyanovinyl-substituted species as well as an expanded dipyrrin analogue bearing both a dicyanomethylene and a tricyanovinyl substituent at the α-positions. These novel compounds exhibit absorption spectral features perturbed by the electron-withdrawing substituents. Unique protonation-induced spectral changes were also disclosed.