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: 2010 vol. 2010 p. 965 - 974

1434-1948

Two 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 charac- terized. The crystal structure of 1 shows that salbutO3– acts as a pentadentate ligand through the two phenolato-O, two imino-N, and one alcoholato-O atoms, and the sixth coordi- nation position is occupied by the azido-N atom, resulting in a slightly distorted N3O3 donor set around the MnIV ion. ESI- MS, UV/Vis, and 1H NMR spectroscopy were used for solu- tion studies. In methanol and dmf, the starting complexes are converted into [MnIII(salbutO)] and its dimeric form. The E1/2 of MnIII/MnIV (ca. 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 ϫ 106 M–1 s–1 and 1.43 μM, respectively, which were obtained through the nitro blue tetrazolium photoreduction inhibition SOD assay, in aqueous solution of pH 7.8. The Mn-salbutO complexes also show catalase activity in methanol and dmf, with kcat = 1.6 M–2 s–1 and 5.6 M–1 s–1, respectively, an advantageous prop- erty for acting as scavenger of reactive oxygen species (ROS). This valuable conjunction of properties results from the con- version of [MnIV(salbutO)X] into [MnIII(salbutO)]2 in equilib- rium with its monomer [MnIII(salbutO)].