Synthesis, Characterization and Combined Superoxide Dismutase and Catalase Activities of Manganese Complexes of 1,4-Bis(salicylidenamino)butan-2-ol

DAIER, V.; MORENO, D.; DUHAYON, C.; TUCHAGUES, J. P.; SIGNORELLA, S.

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2009

1434-1948

Two new MnIV complexes of general formula [Mn(salbutO)X] (H3salbutO = 1,4-bis[(salicylidenamino]butan-2-ol, 1: X = N3, 2: X = SCN) have been prepared and structurally characterized. The crystal structure of 1 shows that salbutO3- acts as a pentadentate ligand through the two phenolato-O, two imino-N and alcoholato-O atoms and the sixth coordination position is occupied by the azide-N atom, resulting in a slightly distorted N3O3 donor set around the Mn ion. ESI-MS, UV-vis. 1H NMR and EPR spectroscopies were used for solution studies. In DMF and methanol, the starting complexes convert into [MnIII(salbutO(H))]0/+ in equilibrium with the dimer. The E1/2 of the MnIII/MnIV couple (~ 0.4 V vs. Ag/AgCl) allows this couple to efficiently catalyze the dismutation of O2·- with catalytic rate constant and IC50 values of 1.91 x 106 M-1 s-1 and 1.43 mM, respectively, obtained by the nitro blue tetrazolium photoreduction inhibition SOD assay, in aqueous solution at pH 7.8. The complexes also show catalase activity in DMF and methanol. The catalase reaction is faster in methanol (19.9 M-1 s-1) than in DMF (5.6 M-1 s-1), but in the last solvent the catalyst is able to disproportionate higher number of equivalents of H2O2.