title: Free radical production by hydroxy-salen manganese complexes studied by ESR and XANES.
abstract: 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.
authors.affiliation: Laboratoire de Chimie Organique Physique, CNRS ESA8009 USTL, Bâtiment C3, 59655, Villeneuve d'Ascq, France. herve.vezin@univ-lille.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Vezin
authors.forename: Eric
authors.initials: E
authors.lastname: Lamour
authors.forename: Sylvain
authors.initials: S
authors.lastname: Routier
authors.forename: Françoise
authors.initials: F
authors.lastname: Villain
authors.forename: Christian
authors.initials: C
authors.lastname: Bailly
authors.forename: Jean Luc
authors.initials: JL
authors.lastname: Bernier
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Catteau
mesh_terms: 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
chemical_list: D005029:Ethylenediamines; D005609:Free Radicals; D015335:Molecular Probes; D009942:Organometallic Compounds; D013481:Superoxides; C090577:N,N'-bis(salicylideneamino)ethane-manganese(II)