title: L-ascorbic acid quenching of singlet delta molecular oxygen in aqueous media: generalized antioxidant property of vitamin C.
abstract: L-ascorbic acid quenches singlet (1 delta g) molecular oxygen in aqueous media (pH 6.8 for [1H]H2O and pD 7.2 for [2H]D2O) as measured directly by monitoring (0,0) 1 delta g leads to 3 sigma-g emission at 1.28 micron. Singlet oxygen was generated at room temperature in the solutions via photosensitization of sodium chrysene sulfonate; this sulfonated polycyclic hydrocarbon was synthesized to provide a water soluble chromophore inert to usual dye-ascorbate photobleaching. A marked isotope effect is found; kHQ2O is 3.3 times faster than kDQ2O, suggesting ascorbic acid is chemically quenching singlet oxygen.
mesh_terms: D001205:Ascorbic Acid; D003903:Deuterium; D017666:Deuterium Oxide; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen; D010777:Photochemistry; D026082:Singlet Oxygen; D014867:Water
chemical_list: D014867:Water; D026082:Singlet Oxygen; D003903:Deuterium; D017666:Deuterium Oxide; D001205:Ascorbic Acid; D010100:Oxygen