Neutralization of Reactive Oxygen Species at Dinuclear Cu(II)-Cores: Tuning the Antioxidant Manifold in Water by Ligand Design

Dinuclear Cu₂(II,II)-cores stabilized by the N₃O donorset of HL¹ = (2-{[[di­(2-pyridyl)­methyl]­(methyl)­amino]­methyl}­phenol), HL² = 2-({[di­(2-pyridyl)­methyl]­amino}­methyl)­phenol), and HL³ = 2-({[di­(2-pyridyl)­methyl]­amino}­methyl)-4-nitrophenol display a unique superoxide dismutase (SOD) combined with catalase (CAT)-like activity in water, at neutral pH. The Cu₂L¹₂ < Cu₂L²₂ < Cu₂L³₂ structure–reactivity trend puts a spotlight on the electron-deficient core of Cu₂L³₂ that exhibits the highest SOD (log k_cat(O₂^•–) = 7.55) and CAT-like (k_H2O2 = 0.66 M^–1 s^–1) performance. Time-lapse ESI-MS and EPR experiments indicate that a dimeric core is essential for oxygenic turnover upon H₂O₂ decomposition.