Complexes of tetra-and hexa-coordinated germanium Adr Cat 2 Ge (1, Adr Cat = adrenaline catecholate), Ald Cat 2 Ge (2, Ald Cat = 4-formylcatecholate), Ald Cat 3 Ge(Et 3 NH) 2 (3) were synthesized by the reaction of germanium dioxide with adrenaline and 3,4-dihydroxybenzaldehyde in aqueous solution. The structures of the complexes were confirmed by 1 H and 13 C NMR and IR spectroscopy, HRMS, and elemental analysis. Cyclic voltammetry in phosphate buffer solutions (pH = 6.86) has shown the oxidation potentials E p of these complexes to be shifted by ca. 330-360 mV to more positive potentials compared to the parent aromatic diols, which means that their electron-releasing properties were diminished by about 7.6-8.3 kcal mol -1 . A study of the kinetics of the reaction of these complexes with 2,2diphenyl-1-picrylhydrazyl (DPPH) free radical in the presence of [a] N.

Using cyclic voltammetry, UV and 1H NMR spectroscopy, we have investigated the effect of 2‐carboxyethylgermanium (Ge‐132), the most common germanium‐containing dietary supplement, on the antioxidant activity of adrenaline in aqueous solutions. The complex formed by adrenaline and Ge‐132 is oxidizable at 400 mV more positive potentials compared to non‐coordinated adrenaline which corresponds to its 9 kcal/mol more difficult oxidation. An equilibrium constant of the complex formation was estimated (1300 m–1). It was shown that at the concentrations <10–3 m the complex Ge‐132‐adrenaline is mostly dissociated to the initial compounds, and the influence of Ge‐132 on the antioxidant properties of adrenaline becomes significant only when the former is in excess. Considering that such concentrations are typical for physiological conditions, this fact can be significant in identifying the mechanism of the biological action of Ge‐132 and its interference with the biological catechols.