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Publications

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2023



  • M. Balas, A. Mayoufi, R. Villanneau, et F. Launay, « Revisiting the Mukaiyama-type epoxidation for the conversion of styrene into styrene carbonate in the presence of O <sub>2</sub> and CO <sub>2</sub> », Reaction Chemistry & Engineering, p. 10.1039.D2RE00330A, 2023.
    Résumé : Alkene epoxidation using the Mukaiyama process involving O 2 and a sacrificial aldehyde, as the first step of the global alkene oxidative carboxylation, does not necessarily require a metal catalyst. , Since its first report in the early 1990s, Mukaiyama-type aerobic epoxidation involving the presence of an aldehyde as an electron donor is considered as an interesting oxidation reaction. Among the various metal catalysts efficient for this process, salen-type complexes have many advantages: i) cheap Schiff-base ligands can be easily synthesized and functionalized, ii) their metal complexes are described with most transition metals from the periodic table and iii) these compounds are also efficient for the catalytic formation of cyclic carbonates from epoxides and CO 2 , which makes them ideal candidates for the oxidative carboxylation of alkenes. The present work aimed at revisiting the aerobic oxidation of styrene using Cr( iii ) and Mn( iii ) salen complexes in the presence of isobutyraldehyde with the idea to further use these complexes (without any work-up), as co-catalysts for the formation of styrene carbonate under CO 2 pressure. However, contrary to what is often described in the literature, the present study showed that the introduction of a metal catalyst is not necessary for the epoxidation of styrene at 80 °C in benzonitrile. In our hands, yields of ca. 15% of styrene carbonate were obtained from styrene using O 2 (3.5 bar) and CO 2 (11 bar) as reagents in the presence of isobutyraldehyde (2.5 eq), tetrabutylammonium bromide ( ca. 2 mol%) and the Cr( iii ) salen complex ( ca. 1 mol%). Apparently, the oxidation of Cr( iii ) to Cr( vi ) species in the presence of O 2 and isobutyraldehyde is detrimental to the kinetics of the tetrabutylammonium bromide-catalyzed cycloaddition of CO 2 to styrene oxide.
    Mots-clés : E-POM, POLE 2.
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2022



  • E. Atrián-Blasco, L. de Cremoux, X. Lin, R. Mitchell-Heggs, L. Sabater, S. Blanchard, et C. Hureau, « Keggin-type polyoxometalates as Cu( <span style="font-variant:small-caps;">ii</span> ) chelators in the context of Alzheimer's disease », Chemical Communications, vol. 58, nᵒ 14, p. 2367-2370, 2022.
    Résumé : Keggin-type POMs extract Cu( ii ) from the Alzheimer's-related amyloid-β peptide. They prevent Cu(Aβ) ROS production, while ill-defined Cu(Aβ) aggregates are switched to fibrils due to Cu(POM) modulation of the apo-Aβ's assembly. , Two Keggin polyoxometalates were used as new copper ligands to counteract the effects of Cu II (Amyloid-β) interaction. Their ability to remove Cu II from Cu II (Amyloid-β), to stop Cu II (Amyloid-β) induced formation of reactive oxygen species and to restore apo-like self-assembly of Cu II (Amyloid-β) was shown.
    Mots-clés : E-POM, POLE 2.
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  • M. Balas, R. Villanneau, et F. Launay, « Bibliographic survey of the strategies implemented for the one-pot synthesis of cyclic carbonates from styrene and other alkenes using CO2 and green oxidants », Journal of CO2 Utilization, vol. 65, p. 102215, 2022.


  • C. Huez, D. Guérin, S. Lenfant, F. Volatron, M. Calame, M. L. Perrin, A. Proust, et D. Vuillaume, « Redox-controlled conductance of polyoxometalate molecular junctions », Nanoscale, vol. 14, nᵒ 37, p. 13790-13800, sept. 2022.
    Résumé : We demonstrate the reversible in situ photoreduction of molecular junctions of a phosphomolybdate [PMo12O40]3− monolayer self-assembled on flat gold electrodes, connected by the tip of a conductive atomic force microscope. The conductance of the one electron reduced [PMo12O40]4− molecular junction is increased by ∼10, and this open-shell state is stable in the junction in air at room temperature. The analysis of a large current–voltage dataset by unsupervised machine learning and clustering algorithms reveals that the electron transport in the pristine phosphomolybdate junctions leads to symmetric current–voltage curves, controlled by the lowest unoccupied molecular orbital (LUMO) at 0.6–0.7 eV above the Fermi energy with ∼25% of the junctions having a better electronic coupling to the electrodes than the main part of the dataset. This analysis also shows that a small fraction (∼18% of the dataset) of the molecules is already reduced. The UV light in situ photoreduced phosphomolybdate junctions systematically feature slightly asymmetric current–voltage behaviors, which is ascribed to the electron transport mediated by the single occupied molecular orbital (SOMO) nearly at resonance with the Fermi energy of the electrodes and by a closely located single unoccupied molecular orbital (SUMO) at ∼0.3 eV above the SOMO with a weak electronic coupling to the electrodes (∼50% of the dataset) or at ∼0.4 eV but with a better electrode coupling (∼50% of the dataset). These results shed light on the electronic properties of reversible switchable redox polyoxometalates, a key point for potential applications in nanoelectronic devices.
    Mots-clés : E-POM, POLE 2.
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  • S. Hupin, V. Tognetti, F. Rosu, S. Renaudineau, A. Proust, G. Izzet, V. Gabelica, C. Afonso, et H. Lavanant, « Lennard-Jones interaction parameters of Mo and W in He and N2 from collision cross-sections of Lindqvist and Keggin polyoxometalate anions », Physical Chemistry Chemical Physics, vol. 24, nᵒ 26, p. 16156-16166, juill. 2022.
    Résumé : Drift tube ion mobility spectrometry (DTIMS) coupled with mass spectrometry was used to determine the collision cross-sections (DTCCS) of polyoxometalate anions in helium and nitrogen. As the geometry of the ion, more than its mass, determines the collision cross-section with a given drift gas molecule, we found that both Lindqvist ions Mo6O192− and W6O192− had a DTCCSHe value of 103 ± 2 Å2, and both Keggin ions PMo12O403− and PW12O403− had a DTCCSHe value of 170 ± 2 Å2. Similarly, ion mobility experiments in N2 led to DTCCSN2 values of 223 ± 2 Å2 and 339 ± 4 Å2 for Lindqvist and Keggin anions, respectively. Using optimized structures and partial charges determined from density functional theory calculations, followed by CCS calculations via the trajectory method, we determined Lennard-Jones 6-12 potential parameters ε, σ of 5.60 meV, 3.50 Å and 3.75 meV, 4.40 Å for both Mo and W atoms interacting with He and N2, respectively. These parameters reproduced the CCS of polyoxometalates within 2% accuracy.
    Mots-clés : E-POM, POLE 2.
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  • L. K/Bidi, A. Desjonquères, G. Izzet, et G. Guillemot, « H<sub>2</sub> Evolution at a Reduced Hybrid Polyoxometalate and Its Vanadium-Oxo Derivative Used as Molecular Models for Reducible Metal Oxides », Inorganic Chemistry, p. acs.inorgchem.2c01741, juill. 2022.


  • M. Laurans, M. Mattera, R. Salles, L. K’Bidi, P. Gouzerh, S. Renaudineau, F. Volatron, G. Guillemot, S. Blanchard, G. Izzet, A. Solé-Daura, J. M. Poblet, et A. Proust, « When Identification of the Reduction Sites in Mixed Molybdenum/Tungsten Keggin-Type Polyoxometalate Hybrids Turns Out Tricky », Inorganic Chemistry, vol. 61, nᵒ 20, p. 7700-7709, mai 2022.


  • S. Mabrouk, H. Rinnert, L. Balan, J. Jasniewski, S. Blanchard, G. Medjahdi, R. Ben Chaabane, et R. Schneider, « Highly Luminescent and Photostable Core/Shell/Shell ZnSeS/Cu:ZnS/ZnS Quantum Dots Prepared via a Mild Aqueous Route », Nanomaterials, vol. 12, nᵒ 18, p. 3254, sept. 2022.
    Résumé : An aqueous-phase synthesis of 3-mercaptopropionic acid (3-MPA)-capped core/shell/shell ZnSeS/Cu:ZnS/ZnS QDs was developed. The influence of the Cu-dopant location on the photoluminescence (PL) emission intensity was investigated, and the results show that the introduction of the Cu dopant in the first ZnS shell leads to QDs exhibiting the highest PL quantum yield (25%). The influence of the Cu-loading in the dots on the PL emission was also studied, and a shift from blue–green to green was observed with the increase of the Cu doping from 1.25 to 7.5%. ZnSeS/Cu:ZnS/ZnS QDs exhibit an average diameter of 2.1 ± 0.3 nm and are stable for weeks in aqueous solution. Moreover, the dots were found to be photostable under the continuous illumination of an Hg–Xe lamp and in the presence of oxygen, indicating their high potential for applications such as sensing or bio-imaging.
    Mots-clés : E-POM, POLE 2.
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  • Q. Sallembien, P. Aoun, S. Blanchard, L. Bouteiller, et M. Raynal, « Interplay between hydrogen bonding and electron transfer in mixed valence assemblies of triarylamine trisamides », Chemistry – A European Journal, p. chem.202203199, nov. 2022.
    Mots-clés : E-POM, POLE 2, POLE 4, POLYMERES.
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2021



  • P. Galiyeva, H. Rinnert, S. Bouguet-Bonnet, S. Leclerc, L. Balan, H. Alem, S. Blanchard, J. Jasniewski, G. Medjahdi, B. Uralbekov, et R. Schneider, « Mn-Doped Quinary Ag–In–Ga–Zn–S Quantum Dots for Dual-Modal Imaging », ACS Omega, vol. 6, nᵒ 48, p. 33100-33110, déc. 2021.
    Résumé : Doping of transition metals within a semiconductor quantum dot (QD) has a high impact on the optical and magnetic properties of the QD. In this study, we report the synthesis of Mn2+-doped Ag–In–Ga–Zn–S (Mn:AIGZS) QDs via thermolysis of a dithiocarbamate complex of Ag+, In3+, Ga3+, and Zn2+ and of Mn(stearate)2 in oleylamine. The influence of the Mn2+ loading on the photoluminescence (PL) and magnetic properties of the dots are investigated. Mn:AIGZS QDs exhibit a diameter of ca. 2 nm, a high PL quantum yield (up to 41.3% for a 2.5% doping in Mn2+), and robust photo- and colloidal stabilities. The optical properties of Mn:AIGZS QDs are preserved upon transfer into water using the glutathione tetramethylammonium ligand. At the same time, Mn:AIGZS QDs exhibit high relaxivity (r1 = 0.15 mM–1 s–1 and r2 = 0.57 mM–1 s–1 at 298 K and 2.34 T), which shows their potential applicability for bimodal PL/magnetic resonance imaging (MRI) probes.
    Mots-clés : E-POM, POLE 2.
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  • A. Gillet, S. Cher, M. Tassé, T. Blon, S. Alves, G. Izzet, B. Chaudret, A. Proust, P. Demont, F. Volatron, et S. Tricard, « Polarizability is a key parameter for molecular electronics », Nanoscale Horizons, vol. 6, nᵒ 3, p. 271-276, mars 2021.
    Résumé : Identifying descriptors that govern charge transport in molecular electronics is of prime importance for the elaboration of devices. The effects of molecule characteristics, such as size, bulkiness or charge, have been widely reported. Herein, we show that the molecule polarizability can be a crucial parameter to consider. To this end, platinum nanoparticle self-assemblies (PtNP SAs) are synthesized in solution, including a series of polyoxometalates (POMs). The charge of the POM unit can be modified according to the nature of the central heteroatom while keeping its size constant. POM hybrids that display remote terminal thiol functions strongly anchor the PtNP surface to form robust SAs. IV curves, recorded by conductive AFM, show a decrease in Coulomb blockade as the dielectric constant of the POMs increases. In this system, charge transport across molecular junctions can be interpreted as variations in polarizability, which is directly related to the dielectric constant.
    Mots-clés : CSOB, E-POM, POLE 2, POLE 3.
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  • Z. Huo, Y. Liang, S. Yang, D. Zang, R. Farha, M. Goldmann, H. Xu, B. Antoine, E. Matricardi, G. Izzet, A. Proust, et L. Ruhlmann, « Photocurrent generation from visible light irradiation of covalent polyoxometalate–porphyrin copolymers », Electrochimica Acta, vol. 368, p. 137635, févr. 2021.
    Résumé : Four hybrid polyoxometalate–porphyrin copolymer films were obtained by the electrooxidation of zinc-β-octaethylporphyrin (ZnOEP) or 5,15-ditolylporphyrin (H2T2P) in the presence of organosilyl functionalized Keggin-type POMs TBA3[PW11Si2O40C26H16N2] (abbreviated Py-PW11Si2-Py) and Dawson-type POMs TBA6[P2W17Si2O62C26H16N2] (abbreviated Py-P2W17Si2-Py) bearing two remote pyridyl groups. The electropolymerization process of the four copolymers was monitored by EQCM. The obtained copolymers were characterized by UV/Vis spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, and AFM. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation. These studies showed a correlation between impedance and photovoltaic performances, the films based on Dawson type POMs and Zn porphyrins giving the best results. This last system displayed one of the best photocurrent efficiency for a reported POM photosensitized hybrid.
    Mots-clés : Copolymerization, E-POM, Organic–inorganic hybrid composites, Photocurrent generation, POLE 2, Polyoxometalates, Porphyrinoids, Thin films.
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  • X. Zhu, C. Hessin, A. Salamé, L. Sosa‐Vargas, D. Kreher, C. Adachi, A. Proust, P. Mialane, J. Marrot, A. Bouchet, M. Sliwa, S. Méry, B. Heinrich, F. Mathevet, et G. Izzet, « Photoactive Organic/Inorganic Hybrid Materials with Nanosegregated Donor–Acceptor Arrays », Angewandte Chemie International Edition, vol. 60, nᵒ 15, p. 8419-8424, avr. 2021.
    Mots-clés : E-POM, POLE 2, POLE 4, POLYMERES.
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2020



  • S. Nasri, M. Hajji, M. Guergueb, S. Dhifaoui, V. Marvaud, F. Loiseau, F. Molton, T. Roisnel, T. Guerfel, et H. Nasri, « Spectroscopic, Electrochemical, Magnetic and Structural Characterization of an Hexamethylenetetramine Co(II) Porphyrin Complex – Application in the Catalytic Degradation of Vat Yellow 1 dye », Journal of Molecular Structure, p. 129676, nov. 2020.
    Résumé : In this study, a new cobaltous-(hexamethylenetetramine) [meso-tetra(para-methoxyphenyl)porphyrin complex with the formula [CoII(TMPP)(HMTA)] (I) was synthesized. The molecular structure was confirmed in solution by 1H NMR spectroscopy and mass spectrometry methods, and the single crystal X-ray diffraction structure of (I) was determined at both room temperature and low temperature. This species was further characterized by infrared, UV-visible and fluorescence spectroscopies, magnetic susceptibility measurements and cyclic voltammetry. The chemical reactivity behavior was also assessed theoretically through Density Functional Theory (DFT) approach. Magnetic investigation indicates that the Co(II)-HMTA porphyrin (I) species at low temperature is a cobaltous low-spin (S = 1/2) species while at high temperature complex (I) exhibits a spin-crossover low-spin (S = 1/2) ↔ high-spin (S = 3/2). The adsorption kinetic of the “vat yellow 1 dye” was carried out in aqueous solution at pH = 6. The experimental results are better fitted using the pseudo second order model. Furthermore, complex (I) was tested as catalyst in the degradation of the vat yellow 1 dye using an aqueous H2O2 solution and by photodegradation under solar light.
    Mots-clés : E-POM, POLE 2.
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  • Y. Ren, J. Forte, K. Cheaib, N. Vanthuyne, L. Fensterbank, H. Vezin, M. Orio, S. Blanchard, et M. Desage-El Murr, « Optimizing Group Transfer Catalysis by Copper Complex with Redox-Active Ligand in an Entatic State », Iscience, vol. 23, nᵒ 3, p. UNSP 100955, mars 2020.
    Résumé : Metalloenzymes use earth-abundant non-noble metals to perform high-fidelity transformations in the biological world. To ensure chemical efficiency, metalloenzymes have acquired evolutionary reactivity-enhancing tools. Among these, the entatic state model states that a strongly distorted geometry induced by ligands around a metal center gives rise to an energized structure called entatic state, strongly improving the reactivity. However, the original definition refers both to the transfer of electrons or chemical groups, whereas the chemical application of this concept in synthetic systems has mostly focused on electron transfer, therefore eluding chemical transformations. Here we report that a highly strained redox-active ligand enables a copper complex to perform catalytic nitrogen- and carbon-group transfer in as fast as 2 min, thus exhibiting a strong increase in reactivity compared with its unstrained analogue. This report combines two reactivity-enhancing features from metalloenzymes, entasis and redox cofactors, applied to group-transfer catalysis.
    Mots-clés : aziridination, cu, E-POM, galactose-oxidase, generation, MACO, metal-complexes, models, oxidation, POLE 1, POLE 2, radicals, reactivity, site.
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2019

2018



  • T. Zhang, A. Solé-Daura, S. Hostachy, S. Blanchard, C. Paris, Y. Li, J. J. Carbó, J. M. Poblet, A. Proust, et G. Guillemot, « Modeling the Oxygen Vacancy at a Molecular Vanadium(III) Silica-Supported Catalyst », Journal of the American Chemical Society, vol. 140, nᵒ 44, p. 14903-14914, nov. 2018.
    Résumé : Here we report on the use of a silanol-decorated polyoxotungstate, [SbW9O33(tBuSiOH)3]3– (1), as a molecular support to describe the coordination of a vanadium atom at a single-site on silica surfaces. By reacting [V(Mes)3·thf] (Mes = 2,4,6-trimethylphenyl) with 1 in tetrahydrofuran, the vanadium(III) derivative [SbW9O33(tBuSiO)3V(thf)]3– (2) was obtained. Compound 2 displays the paramagnetic behavior expected for a d2-VIII high spin complex (SQUID measurements) with a triplet electronic ground state (ca. 30 kcal·mol–1 more stable than the singlet, from DFT calculations). Compound 2 proves to be a reliable model for reduced isolated-vanadium atom dispersed on silica surfaces [(≡Si—O)3VIII(OH2)], an intermediate that is often proposed in a Mars–van Krevelen type mechanism for partial oxidation of light alcohols. Oxidation of 2 under air produced the oxo-derivative [SbW9O33(tBuSiO)3VO]3– (3). In compound 2, the d2-electrons are localized in degenerated d(V) orbitals, whereas in the electronically analogous bireduced-[SbW9O33(tBuSiO)3VO]5–, 3·(2e), one electron is localized on d(V) orbital and the second one is delocalized on the polyoxotungstic framework, leading to a unique case of a bireduced heteropolyanion derivative with completely decoupled d1-V(IV) and d1-W(V). Our body of experimental results (EPR, magnetic measurements, spectroelectrochemical studies, Raman spectroscopy) and theoretical studies highlights (i) the role of the apical ligand coordination, i.e., thf (σ-donor) vs oxo (π-donor), in destabilizing or stabilizing the d(V) orbitals relative to the d(W) orbitals, and (ii) a geometrical distortion of the O3VO entity that causes a splitting of the degenerated orbitals and the stabilization of one d(V) orbital in the bireduced compound 3·(2e).
    Mots-clés : E-POM, ERMMES, POLE 2.
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2017



  • Q. Arnoux, A. Boucly, V. Barth, R. Benbalagh, A. Cossaro, L. Floreano, M. Silly, F. Sirotti, E. Derat, S. Carniato, F. Bournel, J. - J. Gallet, D. Fichou, L. Tortech, et F. Rochet, « Energy-Level Alignment of a Hole-Transport Organic Layer and ITO: Toward Applications for Organic Electronic Devices », ACS Applied Materials & Interfaces, vol. 9, nᵒ 36, p. 30992-31004, sept. 2017.
    Résumé : 2,2′,6,6′-Tetraphenyl-4,4′-dipyranylidene (DIPO-Ph4) was grown by vacuum deposition on an indium tin oxide (ITO) substrate. The films were characterized by atomic force microscopy as well as synchrotron radiation UV and X-ray photoelectron spectroscopy to gain an insight into the material growth and to better understand the electronic properties of the ITO/DIPO-Ph4 interface. To interpret our spectroscopic data, we consider the formation of cationic DIPO-Ph4 at the ITO interface owing to a charge transfer from the organic layer to the substrate. Ionization energy DFT calculations of the neutral and cationic species substantiate this hypothesis. Finally, we present the energetic diagram of the ITO/DIPO-Ph4 system, and we discuss the application of this interface in various technologically relevant systems, as a hole-injector in OLEDs or as a hole-collector interfacial layer adjacent to the prototypical OPV layer P3HT:PCBM.
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.
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  • M. Piot, S. Hupin, H. Lavanant, C. Afonso, L. Bouteiller, A. Proust, et G. Izzet, « Charge Effect on the Formation of Polyoxometalate-Based Supramolecular Polygons Driven by Metal Coordination », Inorganic Chemistry, vol. 56, nᵒ 14, p. 8490-8496, juill. 2017.
    Résumé : The metal-driven self-assembly of a Keggin-based hybrid bearing two remote pyridine units was investigated. The resulting supramolecular species were identified by combination of 2D diffusion NMR spectroscopy (DOSY) and electrospray ionization mass spectrometry (ESI-MS) as a mixture of molecular triangles and squares. This behavior is different from that of the structural analogue Dawson-based hybrid displaying a higher charge, which only led to the formation of molecular triangles. This study highlights the decisive effect of the charge of the POMs in their self-assembly processes that disfavors the formation of large assemblies. An isothermal titration calorimetry (ITC) experiment confirmed the stronger binding in the case of the Keggin hybrids. A correlation between the diffusion coefficient D and the molecular mass M of the POM-based building block and its coordination oligomers was also observed. We show that the diffusion coefficient of these compounds is mainly determined by their occupied volume rather than by their shape.
    Mots-clés : E-POM, POLE 2, POLE 4, POLYMERES.
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