Laser photolysis studies of electron transfer between triplet naphthoquinones and amines

✍ Scribed by Iwao Amada; Minoru Yamaji; Shin'ichi Tsunoda; Haruo Shizuka

• Book ID: 103992772
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 821 KB
• Volume: 95
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(95)04235-0

✦ Synopsis

E!~'e!ron transfer between triplet naphthoquinones (:~Nap*; 1,4-naphthoquinone, 2-methyl-l,4-naphthoquinone and 2,3-dimethyl-l,4aaphthoquinone in the triplet state) and N,N-dimethylaniline (DMA) or triethylamine (TEA) in acetonitrile (MeCN) and a mixture of M¢CN and HaO (4:1, v/v) was studied by laser photolysis teenniques at 295 K. By analysis of the transient absorption spectrum observed after the completion of electron transfer, the absorption spectra and coefficients of the naphthoquinone anion radicals (Nap'-) were determined on the basis of those of the DMA cation radical (DMA "+ ) in MeCN and MeCN-H20 (4:!, v/v). The values of the rate constants (k~,) for electron transfer between SNap* and DMA were found to be close to those for diffusion-controlled processes as predicted by the Rehm-Weller theory on electron transfer. Using the determined molar absorption coefficients of Nap'-, the efficiencies (/~d) for the formation of Nap'-and DMA "+ were shown to be unity ;.iace the radical ion pair produced (3[Nap'-+DMA'+]) readily dissociates into Nap'-and DMA "+ due to the triplet spin multiplicity.