Helicenes Grafted with 1,1,4,4‐Tetracyanobutadiene Moieties: π‐Helical Push–Pull Systems with Strong Electronic Circular Dichroism and Two‐Photon Absorption

Enantiopure P- and M-carbo[6]helicenes substituted with one or two tetracyanobutadienes in positions 2 and 15 have been prepared. Grafting of these accepting groups on the pi-helical core resulted in strong charge transfer effects which highly affected UV-visible, electronic circular dichroism and two-photon absorption responses. The ECD signal was found to be reversibly switched by applying a redox stimulus.