A Case of Fast Photocyclization: The Model of a Downhill Ladder Reaction Pathway for the Bichromophoric Phototrigger 3′,5′-Dimethoxybenzoin Acetate

A downhill ladder reaction pathway for the bichromophoric phototrigger 3',5'-dimethoxybenzoin acetate was mapped using ab initio multiconfigurational methods. These computational results explicitly describe a case of fast photocyclization that overcomes two small barriers (<5.0 kcal/mol) and undergoes three internal conversions (ICs) via efficient nonadiabatic relay of conical intersections among long and short distance charge transfer excited states as well as the n pi* excited and ground states. This novel reaction pathway is a consequence of the interaction of the two chromophores.