Synthesis, characterization and combined superoxide dismutase and catalase activities of manganese complexes of 1,4-bis(salicylidenamino)butan-2-ol

VERÓNICA DAIER; DIEGO MORENO; CARINE DUHAYON; JEAN-PIERRE TUCHAGUES; SANDRA SIGNORELLA

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

Wiley

Año: 2010 p. 965 - 974

1434-1948

Two new MnIII complexes Na[Mn(5-SO3-salpnOH)(H2O)]×5H2O (1) and Na[Mn(5-SO3-salpn)(MeOH)]×4H2O (2)  (5-SO3-salpnOH = 1,3-bis(5-sulphonatosalicylidenamino) propan-2-ol, 5-SO3-salpn = 1,3-bis(5-sulphonatosalicylidenamino)propane) have been prepared and characterized. ESI-MS, UV-vis and 1H NMR spectroscopic studies showed that the two complexes exist in solution as monoanions [Mn(5-SO3-salpn(OH))(solvent)2]-, with the ligand bound to the Mn ion through the two phenolato-O and two imino-N atoms disposed in the equatorial plane. The E1/2 of the MnIII/MnII couple (-47.11 (1) and -77.80 mV (2) vs. Ag/AgCl) allows these complexes to efficiently catalyze the dismutation of O2·-, with catalytic rate constants 2.4 × 106 (1) and 3.6 × 106 (2) M-1 s-1, and IC50 values of 1.14 (1) and 0.77 (2) mM, obtained through the nitro blue tetrazolium photoreduction inhibition SOD assay, in aqueous solution of pH 7.8. The two complexes are also able to disproportionate up to 250 equivalent of H2O2 in aqueous solution of pH 8.0. Their dual SOD/CAT activity, together with the high water solubility, make these compounds particularly attractive as catalytic antioxidants.