Axis 2 - OXIDATION CHEMISTRY
Led by Marie Sircoglou (email@example.com)
A Reversible Electron Relay to Exclude Sacrificial Electron Donors in the Photocatalytic Oxygen Atom Transfer Reaction with O2 in Water. N. T. Vo, Y. Mekmouche, T. Tron, R. Guillot, F. Banse, Z. Halime, M. Sircoglou, W. Leibl, A. Aukauloo, (2019) Angew. Chem. Inter. Ed. 58, 16023-16027
The evil necessity of sacrificial electron donors (SEDs) in the photoactivation of O2 can be ousted by the use of a reversible electron acceptor (methylviologen). It intervenes as an electron carrier from the excited photosensitizer to reduce both O2 and an iron(III) catalyst to form a reactive FeIII–peroxo species for oxygen atom transfer reactions. Oxidation of an organic substrate closes the photocatalytic cycle.
Water as an oxygen atom source
Despite recent advances in the field of molecular catalysis, noble metals based complexes are still the best candidates to promote water oxidation. We are dedicated to understand the factors that govern the activation of a water molecule at more earth abundant metal centers as in nature. We have shown, for instance, the implication of surrounding water molecules in the formation of highly oxidized Mn-oxo species. As part of the Multiplet ANR project we also managed to photoinduce the activation of a water molecule in a photosensitizer-catalyst dyad to photooxydize a substrate using water as the sole source of O.
Implications of remote water molecules on the electron transfer coupled processes at a nonporphyrinic Mn(III)-hydroxido complex. S. El Ghachtouli, B. Lassalle-Kaiser, P. Dorlet, R. Guillot, E. Anxolabéhère-Mallart, C. Costentin, A. Aukauloo (2011) Energy Environ. Sci. 4, 2041-2044
Imidoiodinane-free metal-nitrene generation for photocatalysis application
Nitrogen atom transfer reaction promoted by metal-nitrene species is a main route to the formation of C-N bonds. One of the favored methods consists in reacting a rhodium dimer with an in situ generated imidoiodane, leading concomitantly to the generation iodoarene waste. We discovered that a PCET mechanism – close to the one allowing to generate M=O from M-OH2 – could be undertaken instead, with a better atom economy. We were also able to photoinduce the first electron transfer, thus opening the way to photocatalysis.
Light-Induced Activation of the Du Bois [RhII2(Esp)2] Catalyst for Nitrogen Atom Transfer Reactions. R. Farran, C. Ducloiset, J. Buendia, N. T. Vo, R. Guillot, Z. Halime, P. Dauban, W. Leibl, M. Sircoglou, A. Aukauloo (2017) ChemPhotoChem 103, 15729
Reactivity via redox active ligands
The design of ligands is of primary importance to control the reactivity of metal-oxo species for OAT or HAT reactions. To this end we synthesized a new family of acyclic hemiporphyrinic ligands that is able to contain highly oxidized metals (Mn, Fe, Ru) with the active participation of the ligand through spin delocalization. We are currently looking into the rationalization of their electronic structure-reactivity relationship.
Monoanionic Dipyrrin–Pyridine Ligands: Synthesis, Structure and Photophysical Properties. C. Ducloiset, P. Jouin, E. Paredes, R. Guillot, M. Sircoglou, M. Orio, W. Leibl, A. Aukauloo (2015) Eur. J. Inorg. Chem. 2015 (32), 5405–5410
Oxidation processes usually necessitate powerful oxidizing reagents such as hydrogen peroxide. As an alternative, we reported the photocatalytic activation of O2 at a diiron(II) complex - ruthenium(II) photosensitizer dyad where the dinuclear iron complex mimics the methane monooxygenase catalytic center. This biomimetic approach allowed to photooxidize organic substrates in the absence of strong oxidant by using dioxygen as the sole source of O atom.
Photoassisted Generation of a Dinuclear Iron(III) Peroxo Species and Oxygen-Atom Transfer. F. Avenier, C. Herrero, W. Leibl, A. Desbois, R. Guillot, J-P. Mahy, A. Aukauloo (20013) Angew. Chem. Int. Ed. 52, 3634-3637
For more details, see the comprehensive list of our publications HERE.
Last update on 11.13.2019