Neutralization of Reactive Oxygen Species at Dinuclear Cu(II)-Cores: Tuning the Antioxidant Manifold in Water by Ligand Design
Andrea Squarcina, Alice Santoro, Neal Hickey, Rita De Zorzi, Mauro Carraro, Silvano Geremia, Marco Bortolus, Marilena Di Valentin, Marcella Bonchio
Abstract
Dinuclear Cu-2(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 Cu2L21 < Cu2L22 < Cu2L23 structure-reactivity trend puts a spotlight on the electron-deficient core of Cu2L23 that exhibits the highest SOD (log k(cat) (O-2(center dot-)) = 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.