Free radical production by hydroxy-salen manganese complexes studied by ESR and XANES.
Three salen-Mn(II) complexes bearing hydroxyl groups in either the ortho, para or meta positions have been synthesized and the structures of the metal complexes and their potential to produce free radicals investigated by electron spin resonance (ESR) and X-ray absorption near edge structures (XANES) spectroscopy. All three compounds were shown to generate a high level of superoxide anions in dimethyl sulfoxide (DMSO) solution. The production of oxygen radicals results from a one electron process oxidation of Mn(II) species leading to the formation Mn(III) redox state species, as revealed by a higher XANES edge energy of 2.7 eV. The formation of superoxide anion was characterized by ESR, both directly and via the use of a spin-trapping method. Under reductive condition in the presence of ascorbic acid, the reduction of Mn(III) to Mn(II) leads to the production of hydroxyl radicals by the ortho and para compounds. The efficient production O(2)*- by such salen-Mn complexes could be useful to evaluate the scavenging properties of antioxidant molecules.
Vezin
Hervé
H
Laboratoire de Chimie Organique Physique, CNRS ESA8009 USTL, Bâtiment C3, 59655, Villeneuve d'Ascq, France. herve.vezin@univ-lille.fr
Lamour
Eric
E
Routier
Sylvain
S
Villain
Françoise
F
Bailly
Christian
C
Bernier
Jean Luc
JL
Catteau
Jean Pierre
JP
D004578:Electron Spin Resonance Spectroscopy; D005029:Ethylenediamines / Q000737:chemistry*; D005609:Free Radicals / Q000138:chemical synthesis* / Q000737:chemistry; D015335:Molecular Probes / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D013481:Superoxides / Q000138:chemical synthesis / Q000737:chemistry; D014965:X-Rays
D005029:Ethylenediamines; D005609:Free Radicals; D015335:Molecular Probes; D009942:Organometallic Compounds; D013481:Superoxides; C090577:N,N'-bis(salicylideneamino)ethane-manganese(II)