Abstract
Free radicals are in general very reactive entities capable only of transient existence. Nevertheless, several methods have been devised for their detection and identification, including stabilization by matrix isolation procedures1 and detection by spectroscopic methods. Radicals can be readily produced by oxidation–reduction processes where electrons are transferred from the solute to the matrix or conversely. Here we report the first production of trapped O−2 free radicals generated in a titania-gel matrix by the initial reaction of Ti(III) ions with H2O2 and the subsequent precipitation with NH4OH. We also have indications that the detected paramagnetic species may be complexed to the Ti(IV) ions. A striking feature in our results is the very high 2-year stability of these trapped O−2 radicals. We are able to confirm unequivocally the mechanism proposed by Haber and Weiss to explain the Fenton reagent reactions2.
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Ragai, J. Trapped radicals in titania gels. Nature 325, 703–705 (1987). https://doi.org/10.1038/325703a0
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DOI: https://doi.org/10.1038/325703a0
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