Alain Rabion

Metallophthalocyanine-catalyzed oxidation of catechols by H2O2 and its surrogates

Iron sulfophthalocyanines are powerful catalysts for the oxidation of catechols when using hydrogen peroxide or percarbonate as oxidants. Dichloromaleic acid is an oxidation product of tetrachlorocatechol, indicating that the aromatic ring was cleaved.

Synthesis of di-µ-oxo manganese(III/IV) complexes as functional models of L. Plantarum pseudo-catalase: influence of electronic and steric factors; catalysis and kinetics of hydrogen peroxide disproportionation

Di-µ-oxo dimanganese(III/IV) complexes are efficient catalysts for H2O2 disproportionation in neutral aqueous medium; the activity can be correlated to the electron density on the metal and the accessibility of the catalytic site.

Alkane hydroxylation by a manganese analogue of the iron core from methane monooxygenase

A binuclear manganese (II/II) complex with a µ-hydroxo bridging ligand catalyses the hydroxylation of cyclohexane in the presence of tart-butyl hydroperoxide (TBHP).

Oxidation of 2,4,6-trichlorophenol catalyzed by iron phthalocyanines covalently bound to silica

Abstract The covalent attachment of an iron phthalocyanine with chlorosulfonyl substituents (FePcSO 2 Cl) onto a functionalized 3-aminopropyl-silica has been achieved. This supported catalyst FePcSO 2 Cl-silica is able to degrade a recalcitrant pollutant like 2,4,6-trichlorophenol (TCP) with hydrogen peroxide as oxidant. In order to improve the catalytic efficiency of the grafted iron phthalocyanine complex, modifications of the macrocycle substituents, passivation of the silica surface, variation of the loading of the carrier and addition of an organic cosolvent to the reaction mixture were carried out.

Inhibition of the iron-catalysed formation of hydroxyl radicals by nitrosouracil derivatives: protection of mitochondrial membranes against lipid peroxidation.

A new series of metal ligands containing the 1,3-dimethyl-6-amino-5- nitrosouracil moiety has been synthesized and they have been studied as potential inhibitors of iron-dependent lipid peroxidation. For this purpose, these new derivatives have been tested in the Fenton induced deoxyribose degradation assay, which allows a quantitative measurement of their inhibitory effect towards hydroxyl radical generation. When iron(II) is complexed by these ligands, a strong inhibition of deoxyribose degradation is observed, especially in the case of tris-[2-(1,3-dimethyl-5-nitrosouracil-6-yl)aminoethyl] amine (5). This inhibitory effect is clearly related to a specific complexation of iron(II) and is not due to the direct scavenging of hydroxyl radical by the ligand. Inhibition of the iron mediated Fenton reaction presumably results from inactivation of the reactivity of the metal center towards hydrogen peroxide. These derivatives, as well as long alkyl chain substituted nitrosouracils were evaluated in the protection of biological membranes against lipid peroxidation (induced by iron(II)/dihydroxyfumaric acid and determined with the 2-thiobarbituric acid test). Ligand 5 inhibited lipid peroxidation at a rate similar to Desferal (desferrioxamine B) and slightly higher than bathophenanthroline sulphonate (BPS), which are respectively good iron(III) and iron(II) chelators. When covalently bound with a long alkyl chain, the increase of lipophilic character of the ligand allows its location near the mitochondrial membrane, where lipid peroxidation occurs. Lower concentrations (IC50 = 4 microM) are then necessary to inhibit lipid peroxidation. This IC50 concentration should be compared to those obtained for Trolox (IC50 = 3 microM) or the 21-aminosteroid U74500A (IC50 = 1 microM) described previously.