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Mesoporous silica monoliths containing dispersed FeIII sites have been prepared following a direct and simple synthetic method. The iron‐containing materials are able to catalyze the epoxidation of cyclooctene by H2O2 under mild conditions. Textural and spectrophotometric analyses reveal that, when the thermal treatment temperature of the materials increases (from 500 °C to 1000 °C), the pore diameter of the silica matrix decreases while the formation of small oxo‐iron(III) clusters is promoted. Among the five materials obtained after treatment at 500, 700, 800, 900 or 1000 °C, the one prepared at 700 °C exhibits the best catalytic performances. This indicates that a compromise must be found between several parameters, such as the pore size (which decreases with calcination temperature) and the hydrophobicity of the channel surface (which is favored at higher temperature), for an optimal reactivity. [ABSTRACT FROM AUTHOR]

We report two new FeIII complexes [L1FeIII(H2O)](OTf)2 and [L2FeIII(OTf)], obtained by replacing pyridines by phenolates in a known non‐heme aminopyridine iron complex. While the original, starting aminopyridine [(L52)FeII(MeCN)](PF6) complex is stable in air, the potentials of the new FeIII/II couples decrease to the point that [L2FeII] spontaneously reduces O2 to superoxide. We used it as an O2 activator in an electrochemical setup, as its presence allows to generate superoxide at a much more accessible potential (>500 mV gain). Our aim was to achieve substrate oxidation via the reductive activation of O2. While L2FeIII(OTf) proved to be a good O2 activator but a poor oxidation system, its association with another complex (TPEN)FeII(PF6)2 generates a complementary tandem couple for electro‐assisted oxidation of substrates, working at a very accessible potential: upon reduction, L2FeIII(OTf) activates O2 to superoxide and transfers it to (TPEN)FeII(PF6)2 leading in fine to the oxidation of thioanisole. [ABSTRACT FROM AUTHOR]

Metallo-enzymes are natural catalysts carrying out highly selective and demanding reactions under mild conditions, using readily available metal ions (iron, copper, zinc, etc.). Understanding the factors explaining these performances is thus of fundamental and applicative interest. Classical model complexes displaying significant limitations in reactivity led to the development of supramolecular systems associating a reactive complex to a molecular cavity receptor, in order to not only mimic the first coordination sphere of the metal, but also the supramolecular enzymatic environment (access channel and binding pocket) responsible for their remarkable kinetics and selectivities. Calixarenes and resorcinarenes are particularly suited to this goal due to their wide range of sizes and flexibility. This review illustrates several specific aspects of enzymatic systems that were successfully mimicked with such supramolecular model systems. This toolbox of supramolecular effects could be used for future developments of bioinorganic supramolecular catalysts. [ABSTRACT FROM AUTHOR]