Properties and antioxidant activity of water soluble iron catalysts with Schiff base ligands. Comparison with their manganese counterparts

DAIER, V.; PALOPOLI, C.; HUREAU, C; DE CANDIA, A.; SIGNORELLA, S. R.

ARKIVOC - ONLINE JOURNAL OF ORGANIC CHEMISTRY

ARKAT USA INC

Año: 2011 vol. 2011 p. 327 - 342

1551-7004

Three new iron complexes Na2[Fe(5-SO3-salpn)(H2O)2]OH⋅4H2O (1⋅4H2O), Na2[Fe(5-SO3-salpnOH)(H2O)2]Cl⋅7H2O (2⋅7H2O) and Na2[Fe2(5-SO3-salpentO)(μ-OAc)(μ-(OH)(H2O)2]OH⋅3H2O (3⋅3H2O), where 5-SO3-salpn = 1,3-bis(5-SO3-salicylidenamino)propane, 5-SO3-salpnOH = 1,3-bis(5-SO3- salicylidenamino)propan-2-ol and 5-SO3-sapentOH = 1,5-bis(5-SO3-salicylidenamino)pentan-3-ol, have been obtained and characterized. The ligands tune the redox potential of 1 and 2 within the range required for superoxide dismutase activity, with 2 being less reactive as a result of the formation of an inactive dimer. Complex 3 looses acetate and converts into a μ-oxo-Fe2 species responsible for its catalase activity. The more negative reduction potentials of 1 ? 3 and their lower stability result in rates of superoxide and peroxide disproportionation 10- to 100-times slower than those of the Mn counterparts.