Electrochemical generation of triplet states VI—1. A mechanistic study of the luminescence processes at the anodic cleavage of 2,2′- and 4,4′-bipyranes in presence of aromatic hydrocarbons

✍ Scribed by F. Pragst; R. Ziebig

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 501 KB
• Volume: 23
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(78)80032-2

✦ Synopsis

During the anodic oxidation of mixtures of a fluorescent aromatic hydrocarbon and a 2,2'-or a 4,4'-bipyrane in acetonitrile/benzene the emission of the hydrocarbon is observed. It results from a systematic study using rotating disk and ring-disk electrode techniques that this luminescence is caused by the electron transfer between the pyranyl radicals generated in the anodic cleavage of the bipyrane and the hydrocarbon cation radicals. Measurements in a magnetic field and thermodynamical considerations prove a triplet ECL mechanism. As visible from the ECL intensity-potential curves the pyranyi radicals are generated by two different mechanisms. The heterogeneous one electron oxidation of the bipyrane and following cleavage of a single bond is replaoed with the indirect anodic oxidation by means of the reversible hydrocarbon redox system at more positive potentials