title: Fused-ring derivatives of quinoxalines: spectroscopic characterization and photoinduced processes investigated by EPR spin trapping technique.
abstract: 10-Ethyl-7-oxo-7,10-dihydropyrido[2,3-f]quinoxaline derivatives, synthesized as promising biologically/photobiologically active compounds were characterized by UV/vis, FT-IR and fluorescent spectroscopy. Photoinduced processes of these derivatives were studied by EPR spectroscopy, monitoring in situ the generation of reactive intermediates upon UVA (λmax=365 nm) irradiation. The formation of reactive oxygen species and further oxygen- and carbon-centered radical intermediates was detected and possible reaction routes were suggested. To quantify the investigated processes, the quantum yields of the superoxide radical anion spin-adduct and 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl generation were determined, reflecting the activation of molecular oxygen by the excited state of the quinoxaline derivative.
authors.affiliation: Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava SK-812 37, Slovak Republic. zuzana.barbierikova@stuba.sk.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Barbieriková
authors.affiliation: Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava SK-812 37, Slovak Republic.
authors.forename: Dana
authors.initials: D
authors.lastname: Dvoranová
authors.affiliation: Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-845 38, Slovak Republic.
authors.forename: Maroš
authors.initials: M
authors.lastname: Bella
authors.affiliation: Institute of Organic Chemistry, Catalysis and Petrochemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic.
authors.forename: Viktor
authors.initials: V
authors.lastname: Milata
authors.affiliation: Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-845 36, Slovak Republic.
authors.forename: Adriana
authors.initials: A
authors.lastname: Czímerová
authors.affiliation: Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava SK-812 37, Slovak Republic.
authors.forename: Vlasta
authors.initials: V
authors.lastname: Brezová
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry; D011810:Quinoxalines / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D011810:Quinoxalines; D017382:Reactive Oxygen Species; D013113:Spin Labels; D013481:Superoxides; D010100:Oxygen