Bioinspired Bis(benzimidazole)based Copper(I) Complexes and Spectroscopic Studies at Bis(benzoxazole) Copper(II) Compounds

The active sites of type III copper proteins (i.e. tyrosinase) provide inspiration for the development of copper complexes for the activation of O2 as well as for catalytic oxidation and oxygenation reactions of CH substrates. These reactions often proceed via highly reactive CuII2(μ-η2:η2-peroxo) (P) or CuIII2(μ-oxo)2 (O) intermediates. Consequently, the preparation of these intermediates and a comparison of their reactivity are important aspects of bioinorganic Cu/O2 chemistry. We recently introduced bis(benzimidazole) based ligands for bioinspired Cu/O2 chemistry, and we showed that these ligands are potentially proton-responsive. This allowed for the reversible interconversion between P and O intermediates by (de)protonation to occur s at the ligand periphery, which may be biologically relevant in pH-dependent protonation state changes of histidine ligands in metalloproteins. The second part of this work, the synthesis of bis(benzoxazole) copper(II) compounds was described and the complexes were characterized by several analytical techniques including NMR, UV-vis, IR spectroscopies as well as cyclic voltammetry and spectroelectrochemistry. In the future, obtained homoleptic copper(II) complexes might be used as redox mediators in dye sensitized solar solar cells.2021-05-1