Electron-Transfer Reactivity of a Biomimetic Fe(III)-Cu(II) Complex under Biologically Relevant Reducing Conditions

This study investigates the redox reactivity of a biomimetic heterobinuclear Fe(III)-Cu(II) complex,FeCubpbpmpBr(μ-OHCu)(H₂O)₂ , previously known as a structural and functional model of purple acid phosphatases (PAPs). While such complexes have been widely studied for their hydrolytic activity, their behavior under biologically relevant reducing conditions remains largely unexplored. Using UV-Vis spectroscopy, the complex's response to glutathione (GSH) and sodium ascorbate (NaAsc) was evaluated. The complex showed high stability toward GSH but underwent significant spectral changes with NaAsc, indicating an active redox process at the heterobinuclear center. Nitro blue tetrazolium (NBT) reduction assays further confirmed this behavior: the complex markedly accelerated NBT reduction compared to ascorbate alone. These findings reveal previously unrecognized electron-transfer capabilities in this classical PAP biomimetic complex, expanding its relevance beyond hydrolytic chemistry and pointing to new directions in bioinorganic and medicinal chemistry research