Photooxidation von Leukofarbstoffen. VIII. Kurzzeitspektroskopische Untersuchungen zum Mechanismus der Photooxidation von Leukokristallviolett

Abstract

Photooxidation of Leuco Dyes. VIII. Time Resolved Investigations of the Mechanism of the Photooxidation of Leucocrystal Violet The photooxidation of leucocrystal violet has been reexamined by means of conventional and laser flash photolysis as well as spin trap experiments. Three radical transients have been observed and assigned to the cation radical (λmax ≈ 490, 530 nm), the neutral radical with oneNCH3CH2 moiety (λmax ≈ 480 nm) and the triphenyl methyl radical derivative (λmax ≈ 400 nm).

The Chemistry of Leuco Triarylmethanes

“…Decay of the radical cation results in the formation of a dye cation 20 and a hydrogen atom. The presence of the radical cation 19, the dye cation 20 as well as radical 21 has been shown by conventional and laser flash photolysis and by spin trap 36 experiments. Photolysis of leuco nitriles of Malachite Green and Crystal Violet suggests charge transfer between the electron-donor (-NMe 2 ) and electron-acceptor (-CN) groups.…”