Characterization and catalytic activity of Mn (salen) immobilized on silica by various strategies

International audienceDifferent strategies were applied to prepare supported Mn(salen) on fumed silica and to explore the effect of the interaction nature between the active sites and the surface on the catalytic activity. Direct and multistep grafting methods were used: the silica surface was silylated and the metal complex was modified in order to achieve different metal complex/surface interactions. In the speculated strategy, the covalent binding was provided through a cross linker. The resulting systems were characterized by IR in diffuse reflexion mode (DRIFT), thermogravimetric analysis (TG) and chemical analysis. Then, homogenous and heterogeneous catalysts were used for cyclohexene oxidation with tert-Butyl hydroperoxide (TBHP). Results show that organo-metalic complexes are not totally stable during the immobilization procedure when the surface is previously functionalized. The heterogeneous catalyst efficiency is more dependent on the preparation way rather than on the amount of manganese at the surface. The tested solids showed the absence of important leaching phenomena, regardless of the interaction nature between the active sites and the surfac