Hydroxyl Radical Generation by the H2O2/CuII/Phenanthroline System under Both Neutral and Alkaline Conditions: An EPR/Spin-Trapping Investigation

The copper–phenanthroline complex CuI(Phen)2 was the first artificial nuclease studied in biology. mechanism responsible for this activity involves CuII(Phen)2 and H2O2. Even if H2O2/Cu systems have been extensively biology oxidative chemistry, most of these studies were carried out at physiological pH only, little information is available on generation radicals by H2O2/CuII-Phen system. In context paper pulp bleaching to improve ability H2O2, system has investigated, mostly alkaline pH, more recently near-neutral case dyed cellulosic fibers. Hence, aims studying production with pHs. Using EPR/spin-trapping method, HO• formation monitored understand mechanisms involved. DMPO used as a spin-trap form DMPO–OH presence HO•, two scavengers compared identify origin observed adduct, nucleophilic addition water onto leads same adduct. H2O2 decomposition enhanced CuII–Phen (and only slightly CuSO4), reaching level similar Fenton reagent pH. This evidences role Phen, which improves effect CuII tuning electronic structure structural properties corresponding complexes.