INTERSYSTEM CROSSING KINETICS OF AROMATIC KETONES IN CONDENSED PHASE

We compare the kinetics of intersystem crossing at room temperature in different solvents for a family of aromatic ketones: benzophenone, anthrone, xanthone, and para-substituted benzophenones. We report our recent observations: (1) fast buildup (k1-1 ≤ 10 ps) of anthrone transient absorption in dioxane followed by a long (k2-1 ∼ 175 ps) decay; (2) fast buildup (k-1 ≤ 10 ps) of anthrone transient absorption in benzene; (3) fast buildup (k-1 = 8 ± 2 ps) of benzophenone transient absorption in ethanol; (4) fast buildup (k-1 = 6.5 ± 2 ps) of 4,4′-dimethoxybenzophenone transient absorption in benzene. We conclude that the rates of intersystem crossing for this family of aromatic ketones are all approximately the same. © 1978 American Chemical Society.