The reaction of copper-2,9-dimethyl-1,10-phenanthroline with hydrogen peroxide |
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Authors: | TM Florence JL Stauber KJ Mann |
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Institution: | CSIRO Division of Energy Chemistry, Sutherland, Australia |
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Abstract: | The copper complex of 2,9-dimethyl-1,10-phenanthroline(2,9-dmp) is accumulated by a variety of organisms and is highly toxic. Bioaccumulation depends on reduction of copper(II) to (I), since only the copper(I)-2,9-dmp complex is lipophilic. In the case of the marine diatom, Nitzschia closterium, it is proposed that hydrogen peroxide, produced by the algae during photosynthesis, is the in vivo reductant. Hydrogen peroxide rapidly reduces copper(II)-2,9-dmp, but an excess of H2O2 leads to destruction of the yellow copper(I) complex. Rate constants for the formation and degradation of the yellow complex are reported. Oxygen, light, and a hydroxylating agent are released during the degradation reaction. A reaction mechanism is proposed for the destruction of copper-2,9-dmp by excess H2O2, involving attack on the 5, 6 positions of the phenanthroline ring by hydroxyl radical, then further oxidation by singlet oxygen and H2O2. These in vivo degradation reactions are believed to be the cause of the extreme toxicity of the complex. |
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Keywords: | Address reprint requests to Dr T M Florence CSIRO Division of Energy Chemistry Private Mail Bag 7 Sutherland NSW 2232 Australia |
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