Abstract
In our search to establish a reference ·OH production system with respect to which the reactivity of copper(II) complexes could then be tested, the influence of free Cu2+ ions on the Cu+/H2O2 reaction has been investigated.
This influence depends on the CCu2+/CCu+ ratio. At low Cu2+ concentrations, ·OH damage to various detector molecules decreases with increasing Cu2+ concentrations until CCu2+/CCu+ reaches unity. Above this value, ·OH damage increases sharply until CCu2+/CCu+ becomes equal to 5 with salicylate and 2 with deoxyribose, ratios for which the protective effect of Cu2+ cancels. Finally, at higher concentrations, Cu2+ ions logically add their own ·OH production to that normally expected from Cu+ ions. The possible origin of this unprecedented alternate effect has been discussed. The possible influence of Cu+ ions on the generation of ·OH radicals by water gamma radiolysis has also been tested and, as already established for Cu2+ in a previous work, shown to be nonexistent. This definitely confirms that either form of ionised copper cannot scavenge ·OH radicals in the absence of a Iigand.