Mechanism of the photoreactions of fulgides based on 1,2-dimethyl-3-formylindole

Multiplicity-driven photochromism controls three-state fulgimide photoswitches

“…Nevertheless, we hypothesized that opting for the triplet excited state could solve this problem. Judging from phosphorescence measurements of a similar fulgide, 24 the triplet state energy of Z should be approximately 3 kcal mol −1 lower than that of E . Accordingly, under adiabatic conditions, relaxation from the triplet state of E may yield Z .…”

“…This deactivation cannot be induced thermally, because E is thermally more stable than Z, or by irradiation of E, which triggers rapid cyclization to C. Nevertheless, we hypothesized that opting for the triplet excited state could solve this problem. Judging from phosphorescence measurements of a similar fulgide, 24 the triplet state energy of Z Scheme 3 Photoinduced fulgimide isomerization and outcome of E isomerization based on excited-state multiplicity. should be approximately 3 kcal mol À1 lower than that of E. Accordingly, under adiabatic conditions, relaxation from the triplet state of E may yield Z.…”