title: Reduction of isoviolanthrone by reaction with photogenerated radicals.
abstract: The properties of isoviolanthrone (V(1)) and its corresponding dihydro form (V(1)-H(2)) in argon-saturated 1-phenylethanol in the presence of acetophenone were examined by photophysical and photochemical methods. Upon photolysis of the sensitizer, a radical-induced reduction of V(1) to V(1)-H(2) occurs. The quantum yield of this reduction is close to unity. The fluorescence of V(1) has a quantum yield of 0.08, for V(1)-H(2)Φ(f) is strongly enhanced and the emission maximum is blue-shifted. The ketyl radical, the semiquinone radical and V(1)-H(2) were observed in this sequence by flash photolysis. V(1)-H(2) is unstable and undergoes oxidation to V(1) on admission of oxygen.
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie, D-45413, Mülheim an der Ruhr, Germany.
authors.forename: Henry
authors.initials: H
authors.lastname: Gruen
authors.forename: Helmut
authors.initials: H
authors.lastname: Görner
mesh_terms: D001128:Argon / Q000737:chemistry; D001580:Benzopyrenes / Q000737:chemistry*; D001592:Benzyl Alcohols / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D010782:Photolysis; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D001580:Benzopyrenes; D001592:Benzyl Alcohols; D005609:Free Radicals; C095681:violanthrone; D001128:Argon; C002017:methylphenyl carbinol