Circular Photoinduced Electron Transfer in a Donor-Acceptor- Acceptor Triad

An electron‐donor‐acceptor‐acceptor (D‐A1‐A2) triad has been developed that provides the first proof‐of‐concept for a photoinitiated molecular circuit. After photoexcitation into an optical charge‐transfer transition between D and A1, subsequent thermal electron‐transfer from A1.− to A2 is followed by geometric rearrangement in the D.+‐A1‐A2.− charge‐separated state to form an ion‐pair contact. This facilitates “forward” charge recombination between A2.− and D.+ to complete the molecular circuit with an estimated quantum efficiency of 4 % in toluene at 298 K.