IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Tuning the oxidation states of diMn mimics of manganese catalases
Autor/es:
SIGNORELLA, S.
Lugar:
Florianópolis
Reunión:
Conferencia; 18th International Conference on Biological Inorganic Chemistry; 2017
Institución organizadora:
Universidad de Santa Catarina
Resumen:
We evaluated the CAT activity of phenoxo-bridged diMn complexes of heptadentate ligands where terminal pyridyl were replaced by carboxylato or phenolato groups (O-rich coordination sphere, O5/N ratio), aimed at determining the effect of the terminal groups on the active oxidation states of this kind of complexes. Two new complexes, [Mn2L1(OH)2]Na and [Mn2L2(OMe)], where L1 = 5-methyl-2-hydroxy-1,3-xylene-alpha,alpha-diamine-N,N,N?,N?-tetraacetato and L2 = 2,6-bis{[(carboxymethyl)(2-hydroxybenzyl)amino]methyl}-4-methylphenolato, were tested for catalase activity in methanol. ESI-mass spectrometry, electronic and EPR spectroscopy showed that these complexes employ homovalent MnII2/MnIII2 oxidation states for H2O2 disproportionation, with good efficiency in the protic medium and TON > 1000. The present results show that carboxylato groups not only enhance catalytic activity (compared to pyridyl groups) acting as internal bases to assist deprotonation of H2O2 but also favor the formation of homovalent active diMn species.