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Accueil > Les équipes > Edifices PolyMétalliques (E-POM) > Publications

Publications

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2017



  • G. Izzet, F. Volatron, et A. Proust, « Tailor–made Covalent Organic-Inorganic Polyoxometalate Hybrids: Versatile Platforms for the Elaboration of Functional Molecular Architectures », The Chemical Record, vol. 17, nᵒ 2, p. 250-266.
    Résumé : Post-functionalization of organically modified polyoxometalates (POMs) is a powerful synthetic tool to devise functional building blocks for the rational elaboration of POM-based molecular materials. In this personal account we focus on iodoaryl-terminated POM platforms, describe reliable routes to the synthesis of covalent organic-inorganic POM-based hybrids and their integration into advanced molecular architectures or multi-scale assemblies as well as their immobilization onto surfaces. Valorisation of the remarkable redox properties of POMs in the fields of artificial synthesis and molecular electronic is especially considered.
    Mots-clés : artificial photosynthesis, E-POM, modified electrodes, organic-inorganic hybrids, palladium cross-coupling, POLE 2, Polyoxometalates.


  • A. Parrot, A. Bernard, A. Jacquart, S. A. Serapian, C. Bo, E. Derat, O. Oms, A. Dolbecq, A. Proust, R. Métivier, P. Mialane, et G. Izzet, « Photochromism and Dual-Color Fluorescence in a Polyoxometalate–Benzospiropyran Molecular Switch », Angewandte Chemie International Edition, vol. 56, nᵒ 17, p. 4872-4876.
    Résumé : The photophysical properties of a Keggin-type polyoxometalate (POM) covalently bounded to a benzospiropyran (BSPR) unit have been investigated. These studies reveal that both closed and open forms are emissive with distinct spectral features (λem (closed form)=530 nm, λem (open form)=670 nm) and that the fluorescence of the BSPR unit of the hybrid is considerably enhanced compared to BSPR parent compounds. While the fluorescence excitation energy of the BSPR reference compounds (370 nm) is close to the intense absorption responsible of the photochromic character (350 nm), the fluorescence excitation of the hybrid is shifted to lower energy (400 nm), improving the population of the emissive state. Combined NOESY NMR and theoretical calculations of the closed form of the hybrid give an intimate understanding of the conformation adopted by the hybrid and show that the nitroaryl moieties of the BSPR is folded toward the POM, which should affect the electronic properties of the BSPR.
    Mots-clés : density functional calculations, E-POM, fluorescence, MACO, molecular photoswitches, photochromism, POLE 1, POLE 2, Polyoxometalates.

2016



  • J. J. Baldoví, Y. Duan, C. Bustos, S. Cardona-Serra, P. Gouzerh, R. Villanneau, G. Gontard, J. M. Clemente-Juan, A. Gaita-Ariño, C. Giménez-Saiz, A. Proust, et E. Coronado, « Single ion magnets based on lanthanoid polyoxomolybdate complexes », Dalton Transactions, vol. 45, nᵒ 42, p. 16653 - 16660.
    Résumé : Polyoxometalate (POM) chemistry has recently offered excellent examples of single ion magnets (SIMs) and molecular spin qubits. Compared with conventional coordination compounds, POMs provide rigid and highly symmetric coordination sites. However, all POM-based SIMs reported to date exhibit a very limited range of possibilities for chemical processability. We present herein two new families of POM-based SIMs which are soluble in organic solvents: [Ln(β-Mo8O26)2]5− {LnIII = Tb, Dy, Ho, Er, Tm and Yb} and the functionalised POMs [Ln{Mo5O13(OMe)4NNC6H4-p-NO2}2]3− {LnIII = Tb, Dy, Ho, Er, Yb and Nd}. In addition, these two families represent the first SIMs based on polyoxomolybdates. A magneto-structural analysis of these families is presented, which is based on an effective crystal field model, and compared with the results reported in analogous lanthanoid SIMs based on polyoxotungstates.
    Mots-clés : E-POM, EPOM, POLE 2.


  • R. Breitwieser, T. Auvray, F. Volatron, C. Salzemann, A. - T. Ngo, P. - A. Albouy, A. Proust, et C. Petit, « Binary Superlattices from {Mo132} Polyoxometalates and Maghemite Nanocrystals: Long-Range Ordering and Fine-Tuning of Dipole Interactions », Small, vol. 12, nᵒ 2, p. 220-228.
    Résumé : In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ-Fe2O3) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo132} is demonstrated. To do so, colloidal solutions of oleic acid-capped γ-Fe2O3 and long-chain alkylammonium-encapsulated {Mo132} dispersed in chloroform are mixed together and supported self-organized binary superlattices are obtained upon the solvent evaporation on immersed substrates. Both electronic microscopy and small angles X-ray scattering data reveal an AB-type structure and an enhanced structuration of the magnetic nanocrystals (MNCs) assembly with POMs in octahedral interstices. Therefore, {Mo132} acts as an efficient binder constituent for improving the nanocrystals ordering in 3D films. Interestingly, in the case of didodecyldimethylammonium (C12)-encapsulated POMs, the long-range ordered binary assemblies are obtained while preserving the nanocrystals magnetic properties due to weak POMs–MNCs interactions. On the other hand, POMs of larger effective diameter can be employed as spacer blocks for MNCs as shown by using {Mo132} capped with dioctadecyldimethylammonium (C18) displaying longer chains. In that case, it is shown that POMs can also be used for fine-tuning the dipolar interactions in γ-Fe2O3 nanocrystal assemblies.
    Mots-clés : binary superlattices, E-POM, EPOM, maghemites, magnetic dipolar interactions, POLE 2, Polyoxometalates, {mo132}.


  • N. Bridonneau, L. - M. Chamoreau, G. Gontard, J. - L. Cantin, J. von Bardeleben, et V. Marvaud, « A high-nuclearity metal-cyanide cluster [Mo6Cu14] with photomagnetic properties », vol. 45, nᵒ 23, p. 9412-9418.
    Résumé : A high-nuclearity metal-cyanide cluster [Mo6Cu14] has been prepared and its photomagnetic properties investigated. The photoswitchable magnetic phenomenon observed is thermally reversible (T ≈ 230 K). In the field of photomagnetism, [Mo6Cu14] represents a unique example of a nanocage and the highest nuclearity observed so far.
    Mots-clés : E-POM, EPOM, POLE 2.


  • V. E. Campbell, M. Tonelli, I. Cimatti, J. - B. Moussy, L. Tortech, Y. J. Dappe, E. Rivière, R. Guillot, S. Delprat, R. Mattana, P. Seneor, P. Ohresser, F. Choueikani, E. Otero, F. Koprowiak, V. G. Chilkuri, N. Suaud, N. Guihéry, A. Galtayries, F. Miserque, M. - A. Arrio, P. Sainctavit, et T. Mallah, « Engineering the magnetic coupling and anisotropy at the molecule–magnetic surface interface in molecular spintronic devices », Nature Communications, vol. 7, p. 13646.
    Résumé : Controlling the magnetic response of a molecular device is important for spintronic applications. Here the authors report the self-assembly, magnetic coupling, and anisotropy of two transition metal complexes bound to a ferrimagnetic surface, and probe the role of the nature of the transition metal ion.
    Mots-clés : E-POM, POLE 2.

  • S. Garai, H. Bögge, A. Merca, O. A. Petina, A. Grego, P. Gouzerh, E. T. K. Haupt, I. A. Weinstock, et A. Müller, « Densely Packed Hydrophobic Clustering: Encapsulated Valerates Form a High-Temperature-Stable {Mo132 } Capsule System », Angewandte Chemie (International Ed. in English), vol. 55, nᵒ 23, p. 6634-6637.
    Résumé : Porous molecular nanocontainers of {Mo132 }-type Keplerates offer unique opportunities to study a wide variety of relevant phenomena. An impressive example is provided by the highly reactive {Mo132 -CO3 } capsule, the reaction of which with valeric acid results in the very easy release of carbon dioxide and the uptake of 24 valerate ions/ligands that are integrated as a densely packed aggregate, thus indicating the unique possibility of hydrophobic clustering inside the cavity. Two-dimensional NMR techniques were used to demonstrate the presence of the 24 valerates and the stability of the capsule up to ca. 100 °C. Increasing the number of hydrophobic parts enhances the stability of the whole system. This situation also occurs in biological systems, such as globular proteins or protein pockets.
    Mots-clés : confinement effects, dense packing, E-POM, EPOM, hydrophobic interactions, NMR spectroscopy, POLE 2, porous capsules.


  • L. Huder, C. Rinfray, D. Rouchon, A. Benayad, M. Baraket, G. Izzet, F. Lipp-Bregolin, G. Lapertot, L. Dubois, A. Proust, L. Jansen, et F. Duclairoir, « Evidence for Charge Transfer at the Interface between Hybrid Phosphomolybdate and Epitaxial Graphene », Langmuir, vol. 32, nᵒ 19, p. 4774-4783.
    Résumé :

    The interfacing of polyoxometalates and graphene can be considered to be an innovative way to generate hybrid structures that take advantage of the properties of both components. Polyoxometalates are redox-sensitive and photosensitive compounds with high temperature stability (up to 400 °C for some), showing tunable properties depending on the metal incorporated inside the complex. Graphene has a unique electronic band structure combined with good material properties for electrical and optical applications. The spontaneous, rather than electrochemical, functionalization of epitaxial graphene on SiC with Keggin phosphomolybdate derivative TBA3[PMo11O39{Sn(C6H4)C≡C(C6H4)N2}] (named KMoSn[N2+]) bearing a phenyl diazonium unit is investigated. Graphene decoration is evidenced by means of AFM, Raman, XPS, and cyclic voltammetry, indicating a successful immobilization of the polyoxomolybdate. The covalent bonding of the polyoxometalate to the graphene substrate can be deduced from the appearance of a D band in the Raman spectra and from the loss of mobility in the electrical conduction. High-resolution XPS spectra reveal an electron transfer from the graphene to the Mo complex. The comparison of charge-carrier density measurements before and after grafting supports the p-type doping effect, which is further evidenced by work function UPS measurements.
    Mots-clés : E-POM, EPOM, POLE 2.


  • S. Humbert, G. Izzet, et P. Raybaud, « Competitive adsorption of nitrogen and sulphur compounds on a multisite model of NiMoS catalyst: A theoretical study », Journal of Catalysis, vol. 333, p. 78-93.
    Résumé : Using density functional theory including dispersion corrections, we establish a scale of enthalpies and Gibbs energies of adsorption of various organo-nitrogen molecules on a multisite model of the NiMoS active phase, which includes coordinatively unsaturated Lewis sites (Mo or Ni) and Brønsted –SH sites located on the M-edge and S-edge. Dispersion corrections and entropic effects are shown to impact significantly Gibbs energies of adsorption. In particular, protonation of pyridine derivatives is enhanced at high temperature on the Brønsted –SH sites of the M-edge and S-edge. For pyridine, a vibrational frequency analysis of the adsorption modes is undertaken. Stable adsorption configurations are identified for thiophene and 4,6-DMDBT on Lewis and Brønsted sites, and compared to N-containing molecules. While pyrrole derivatives are weak poisons of adsorption sites, pyridine derivatives are the stronger inhibitors. Furthermore, ammonia exhibits a non-negligible inhibitor character. We finally discuss the impact of inhibitors on 4,6-DMDBT hydrodesulphurization pathways.
    Mots-clés : 4,6-Dimethyldibenzothiophene, density functional theory, E-POM, EPOM, Hydrodenitrogenation, Hydrodesulphurization, Inhibition, NiMoS, Nitrogen compounds, POLE 2, Vibrational modes.


  • G. Izzet, B. Abécassis, D. Brouri, M. Piot, B. Matt, S. A. Serapian, C. Bo, et A. Proust, « Hierarchical Self-Assembly of Polyoxometalate-Based Hybrids Driven by Metal Coordination and Electrostatic Interactions: From Discrete Supramolecular Species to Dense Monodisperse Nanoparticles », Journal of the American Chemical Society, vol. 138, nᵒ 15, p. 5093-5099.
    Résumé : The metal-driven self-assembly processes of a covalent polyoxometalate (POM)-based hybrid bearing remote terpyridine binding sites have been investigated. In a strongly dissociating solvent, a discrete metallomacrocycle, described as a molecular triangle, is formed and characterized by 2D diffusion NMR spectroscopy (DOSY), small-angle X-ray scattering (SAXS), and molecular modeling. In a less dissociating solvent, the primary supramolecular structure, combining negatively charged POMs and cationic metal linkers, further self-assemble through intermolecular electrostatic interactions in a reversible process. The resulting hierarchical assemblies are dense monodisperse nanoparticles composed of ca. 50 POMs that were characterized by SAXS and transmission electron microscopy (TEM). This multiscale organized system directed by metal coordination and electrostatic interactions constitutes a promising step for the future design of POM self-assemblies with controllable structure-directing factors.
    Mots-clés : E-POM, EPOM, POLE 2.


  • G. Izzet, F. Volatron, et A. Proust, « Tailor-made Covalent Organic-Inorganic Polyoxometalate Hybrids: Versatile Platforms for the Elaboration of Functional Molecular Architectures », The Chemical Record, p. n/a-n/a.
    Résumé : Post-functionalization of organically modified polyoxometalates (POMs) is a powerful synthetic tool to devise functional building blocks for the rational elaboration of POM-based molecular materials. In this personal account we focus on iodoaryl-terminated POM platforms, describe reliable routes to the synthesis of covalent organic-inorganic POM-based hybrids and their integration into advanced molecular architectures or multi-scale assemblies as well as their immobilization onto surfaces. Valorisation of the remarkable redox properties of POMs in the fields of artificial synthesis and molecular electronic is especially considered.
    Mots-clés : artificial photosynthesis, E-POM, EPOM, modified electrodes, organic-inorganic hybrids, palladium cross-coupling, POLE 2, Polyoxometalates.


  • J. Jacquet, S. Blanchard, E. Derat, M. D. - E. Murr, et L. Fensterbank, « Redox-ligand sustains controlled generation of CF3 radicals by well-defined copper complex », Chemical Science, vol. 7, nᵒ 3, p. 2030-2036.
    Résumé : A well-defined copper complex bearing iminosemiquinone ligands performs single electron reduction of an electrophilic CF3+ source into CF˙3 radicals. This redox behavior is enabled by the ligand which shuttles through two different redox states (iminosemiquinone and iminobenzoquinone) while the copper center is preserved as a Cu(II). This system was used in the trifluoromethylation of silyl enol ethers, heteroaromatics and in the hydrotrifluoromethylation of alkynes. This is the first example of cooperative redox catalysis for the controlled generation of CF˙3 radicals.
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.


  • J. Jacquet, P. Chaumont, G. Gontard, M. Orio, H. Vezin, S. Blanchard, M. Desage-El Murr, et L. Fensterbank, « C−N Bond Formation from a Masked High-Valent Copper Complex Stabilized by Redox Non-Innocent Ligands », Angewandte Chemie International Edition, vol. 55, nᵒ 36, p. 10712-10716.
    Résumé : The reactivity of a stable copper(II) complex bearing fully oxidized iminobenzoquinone redox ligands towards nucleophiles is described. In sharp contrast with its genuine low-valent counterpart...
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.


  • A. Lombana, C. Rinfray, F. Volatron, G. Izzet, N. Battaglini, S. Alves, P. Decorse, P. Lang, et A. Proust, « Surface Organization of Polyoxometalate Hybrids Steered by a 2D Supramolecular PTCDI/Melamine Network », The Journal of Physical Chemistry C, vol. 120, nᵒ 5, p. 2837-2845.
    Résumé : A 2D supramolecular honeycomb network built on hydrogen bonding of perylene-3,4,9,10-tetracarboxylic acid diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (Melamine) has been self-assembled on Au(111) by a solution processed method. The ability of the porous network to host functional molecular oxides or polyoxometalates (POMs) has been investigated using a functionalized species [PW11O39Ge{p-C6H4-C≡C–C6H4-NHC(O) (CH2)4{-CH(CH2)2S-S-}}]4– (KWGe[S-S]): this inorganic/organic hybrid built on a Keggin-type POM core and an organic tether incorporating a thioctic acid function has been designed to enhance the host–guest interaction by the formation of covalent Au–S bonds. XPS analysis confirmed the presence of the POMs that are covalently held onto the surface. Probed by STM operating under ambient conditions, the spatial organization of the POMs display some reminiscence of the organic template, while monitoring the POM deposition at various immersion times by PM-IRRAS showed that the POM raising at the substrate is fostered.
    Mots-clés : E-POM, EPOM, POLE 2.


  • C. Rinfray, V. Brasiliense, G. Izzet, F. Volatron, S. Alves, C. Combellas, F. Kanoufi, et A. Proust, « Electron Transfer to a Phosphomolybdate Monolayer on Glassy Carbon: Ambivalent Effect of Protonation », Inorganic Chemistry, vol. 55, nᵒ 14, p. 6929-6937.
    Résumé : The polyoxomolybdate hybrid TBA3[PMo11O39{Sn(C6H4)C≡C(C6H4)N2}] KMoSn[N2+] was prepared through Sonogashira-type coupling between TBA4[PMo11O39{Sn(C6H4)I}] KMoSn[I] and an excess of 3,3-diethyl-1-(4-ethynylphenyl)triaz-1-ene bearing a protected diazonium function, followed by its deprotection by the addition of trifluoroacetic acid (TFA). This enlarges the family of organic–inorganic polyoxomolybdate-based hybrids, which has been far less investigated than their related polyoxotungstates. The diazonium function allows for the electrochemical grafting on glassy carbon, and the KMoSn-modified electrode was further probed by cyclic voltammetry. The PMo11Sn core was found to be highly sensitive to protonation, and five bielectronic proton-coupled electron transfer processes were detected in the presence of an excess of TFA, thus corresponding to the injection of up to 10 electrons in the potential range between 0.15 and −0.45 V/SCE. The gain observed in the thermodynamic potentials is however detrimental to the apparent kinetics of the electron transfer, which drops from 500 s–1 in the absence of acid to 12 s–1 in the presence of an excess of TFA.
    Mots-clés : E-POM, EPOM, POLE 2.


  • V. Scalcon, A. Citta, A. Folda, A. Bindoli, M. Salmain, I. Ciofini, S. Blanchard, J. de Jésús Cázares-Marinero, Y. Wang, P. Pigeon, G. Jaouen, A. Vessières, et M. P. Rigobello, « Enzymatic oxidation of ansa-ferrocifen leads to strong and selective thioredoxin reductase inhibition in vitro », Journal of Inorganic Biochemistry.
    Résumé : This paper reports the inhibitory effect on the cytosolic thioredoxin reductase (TrxR1) in vitro by the ansa-ferrocifen derivative (ansa-FcdiOH, 1). We found that 1 decreased only slightly enzyme activity (IC50 = 8 μM), while 1*, the species generated by enzymatic oxidation by the HRP (horseradish peroxidase)/H2O2 mixture, strongly inhibited TrxR1 (IC50 = 0.15 μM). At the same concentrations, neither 1 nor 1* had effect on glutathione reductase (GR). The most potent TrxR1 inhibitor did not appear to be the corresponding quinone methide as it was the case for ferrocifens of the acyclic series, or the stabilized carbocation as in the osmocifen series, but rather the quinone methide radical. This hypothesis was confirmed by ab-initio calculations of the species generated by oxidation of 1 and by EPR spectroscopy. BIAM (biotin-conjugated iodoacetamide) assay showed that 1* targeted both cysteine and selenocysteine of the C-terminal redox center of TrxR1.
    Mots-clés : Ansa-ferrocifen, CHEMBIO, E-POM, Enzymatic oxidation, Ferrocene, POLE 2, POLE 3, Quinone methide radical, Thioredoxin reductase.

2015



  • F. Bentaleb, O. Makrygenni, D. Brouri, C. Coelho Diogo, A. Mehdi, A. Proust, F. Launay, et R. Villanneau, « Efficiency of Polyoxometalate-Based Mesoporous Hybrids as Covalently Anchored Catalysts », Inorganic Chemistry, vol. 54, nᵒ 15, p. 7607-7616.
    Résumé : Polyoxometalate (POM) hybrids have been covalently immobilized through the formation of amide bonds on several types of mesoporous silica. This work allows the comparison of three POM-based mesoporous systems, obtained with three different silica supports in which either the organic functions of the support (amine vs carboxylic acid) and/or the structure of the support itself (SBA-15 vs mesocellular foams (MCF)) were varied. The resulting POM-based mesoporous systems have been studied in particular by high resolution transmission electronic microscopy (HR-TEM) in order to characterize the nanostructuration of the POMs inside the pores/cells of the different materials. We thus have shown that the best distribution and loading in POMs have been reached with SBA-15 functionalized with aminopropyl groups. In this case, the formation of amide bonds in the materials has led to the nonaggregation of the POMs inside the channels of the SBA-15. The catalytic activity of the anchored systems has been evaluated through the epoxidation of cyclooctene and cyclohexene with H2O2 in acetonitrile. The reactivity of the different grafted POMs hybrids has been compared to that in solution (homogeneous conditions). Parallels can be drawn between the distribution of the POMs and the activity of the supported systems. Furthermore, recycling tests together with catalyst filtration experiments during the reaction allowed us to preclude the hypothesis of a significant leaching of the supported catalyst.
    Mots-clés : E-POM, POLE 2.

  • N. Bridonneau, G. Gontard, et V. Marvaud, « A new family of hetero-tri-metallic complexes [M(CuTb)](n) (n=1, 2, infinity; M = Co, Cr, Fe): synthesis, structure and tailored single-molecule magnet behavior », Dalton Transactions, vol. 44, nᵒ 11, p. 5170-5178.
    Résumé : A new family of hetero-tri-metallic complexes [M(CuTb)](n) (M-III = Co, Cr, Fe; n = 1, 2, infinity), composed of three series of three compounds (oligo-and poly-nuclear complexes based on [Cu-Tb] subunits), is presented and fully characterized. These nine compounds, viewed as different assemblies of single-molecule magnet (SMM) building blocks, connected to various hexacyanometalate centers, illustrate how the SMM behavior of the [CuTb] moiety can be modulated via the control of intermolecular interactions. Specifically, the combination of the "non-innocent" diamagnetic [Co-III(CN)(6)](3-) center with a [Cu-Tb](3+) moiety enabled isolation of the magnetic entities, resulting in an improvement of the SMM behavior (ranging from U-eff = 5-7 cm(-1) to 15-17 cm(-1)).
    Mots-clés : 3d-4f complexes, chain magnet, coordination polymers, cu, E-POM, ground-state, heterotrimetallic complexes, ladder-type compounds, lanthanide element, POLE 2, solvent molecules, spin.

  • N. Bridonneau, J. Long, J. - L. Cantin, J. von Bardeleben, S. Pillet, E. - E. Bendeif, D. Aravena, E. Ruiz, et V. Marvaud, « First evidence of light-induced spin transition in molybdenum(IV) », Chemical Communications, vol. 51, nᵒ 39, p. 8229-8232.
    Résumé : Photo-induced spin transition in a molybdenum-zinc complex has been evidenced and fully characterized by Squid magnetometry and several spectroscopies performed under irradiation (IR, EPR, etc.). The phenomenon has been confirmed by X-ray diffraction and DFT calculations yielding a Light-Induced Excited Spin State Trapping Effect (LIESST) on a 4d transition metal ion.
    Mots-clés : chemistry, clusters, crossover, E-POM, iron(ii) complexes, Ligands, magnetic circular-dichroism, molecule, photoinduced magnetization, photomagnetism, POLE 2, Temperature.


  • N. Bridonneau, J. Long, J. - L. Cantin, J. von Bardeleben, D. R. Talham, et V. Marvaud, « Photomagnetic molecular and extended network Langmuir–Blodgett films based on cyanide bridged molybdenum–copper complexes », RSC Advances, vol. 5, nᵒ 22, p. 16696-16701.
    Résumé : Two types of cyanide bridged molybdenum–copper photomagnetic films have been obtained: the first one is based on a molecular [MoCu6] complex, the other being a two-dimensional [MoCu2] coordination network. Both systems employ surfactant functionalized ligands and films were deposited on Melinex substrates using the Langmuir–Blodgett technique. All systems, including monolayer films, showed full retention of the intrinsic photomagnetic properties known for analogous solids as demonstrated by EPR spectroscopy.
    Mots-clés : E-POM, POLE 2.


  • B. Doistau, J. - L. Cantin, L. - M. Chamoreau, V. Marvaud, B. Hasenknopf, et G. Vives, « Mechanical switching of magnetic interaction by tweezers-type complex », Chemical Communications, vol. 51, nᵒ 65, p. 12916-12919.
    Résumé : A control of the interaction between two spin centers was achieved by using a mechanical motion in a terpy(Cu–salphen)2 complex. Upon coordination a conformation change and switching from a paramagnetic to an antiferromagnetically coupled system was observed by EPR and SQUID measurements.
    Mots-clés : E-POM, GOBS, POLE 2, POLE 3, SUPRA.


  • S. Garai, A. Merca, S. Bhowmik, H. E. Moll, H. Li, F. Haso, H. Nogueira, T. Liu, L. Wu, P. Gouzerh, et A. Müller, « Hedgehog-shaped {Mo368} cluster: unique electronic/structural properties, surfactant encapsulation and related self-assembly into vesicles and films », Soft Matter, vol. 11, nᵒ 12, p. 2372-2378.
    Résumé : The hedgehog-shaped {Mo368} cluster shows unique electronic (extremely high extinction coefficient) and structural features, especially regarding its size, the high number of delocalized electrons which allows to measure the surface enhanced Raman scattering (SERS) spectrum and the option for coordination chemistry inside the cavity. Its relative instability in aqueous solution can be overcome by embedment in a hydrophobic shell of dimethyldioctadecylammonium cations. The resulting hybrid self-assembles into spherical vesicles in acetone–water mixtures, according to a process directed by hydrophobic–hydrophilic interactions. It also forms rather stable Langmuir monolayers while a second layer evolves under higher surface pressure, in accordance with a rather low alkyl surface density.
    Mots-clés : E-POM, POLE 2.


  • S. Garai, M. Rubčić, H. Bögge, P. Gouzerh, et A. Müller, « Porous Capsules with a Large Number of Active Sites: Nucleation/Growth under Confined Conditions », Chemistry - A European Journal, vol. 21, nᵒ 11, p. 4321-4325.
    Mots-clés : confinement, E-POM, internal tapestry, molybdenum, nanostructures, POLE 2, Polyoxometalates, sulfite.


  • S. Garai, M. Rubčić, H. Bögge, E. T. K. Haupt, P. Gouzerh, et A. Müller, « A Unique Fluoride Nanocontainer: Porous Molecular Capsules Can Accommodate an Unusually High Number of “Rather Labile” Fluoride Anions », Angewandte Chemie International Edition, vol. 54, nᵒ 20, p. 5879-5882.
    Mots-clés : E-POM, fluorides, POLE 2, Polyoxometalates, porous capsules, receptors, water dimers.


  • M. Girardi, S. Blanchard, S. Griveau, P. Simon, M. Fontecave, F. Bedioui, et A. Proust, « Electro-Assisted Reduction of CO2 to CO and Formaldehyde by (TOA)6[α-SiW11O39Co(_)] Polyoxometalate », European Journal of Inorganic Chemistry, vol. 2015, nᵒ 22, p. 3642-3648.
    Résumé : We report here on the multiproton-multielectron electrochemical reduction of CO2 in homogeneous solution by using (TOA)6[α-SiW11O39Co(_)] (TOA = tetraoctyl ammonium; _ = vacant position in the coordination sphere of Co) as an electrocatalyst. First, the electrochemical behavior of (TOA)6[α-SiW11O39Co(_)] was analyzed in detail by cyclic voltammetry in dichloromethane, studying the influence of the presence of protons and/or CO2. These preliminary results were further used to optimize the conditions of electrolysis in terms of reduction potentials. Analysis of the electrolysis products in the gas and liquid phases show the formation of CO and HCHO without formation of H2. Our results tend to show that the (TOA)6[α-SiW11O39Co(_)] polyoxometalate is a catalyst for CO2 electroreduction, with unique selectivity.
    Mots-clés : carbon dioxide fixation, cobalt, E-POM, Electrochemistry, POLE 2, Polyoxometalates, reduction, Tungsten.


  • G. Guillemot, E. Matricardi, L. - M. Chamoreau, R. Thouvenot, et A. Proust, « Oxidovanadium(V) Anchored to Silanol-Functionalized Polyoxotungstates: Molecular Models for Single-Site Silica-Supported Vanadium Catalysts », ACS Catalysis, vol. 5, nᵒ 12, p. 7415-7423.
    Résumé : The metalation of two different types of silanol-decorated polyoxotungstates, [XW9O34?x(tBuSiOH)3]3? (X = P, x = 0; X = Sb, x = 1) and [PW10O36(tBuSiOH)2]3?, by Cl3VO or (iPrO)3VO has been achieved. The characterization of the resulting oxidovanadium(V) complexes [XW9O34?x(tBuSiO)3VO]3? (X = P, 3; X = Sb, 3?) and [PW10O36(tBuSiO)2VO(iPrO)]3? (4) has been fully detailed, including X-ray analysis. These compounds are present in monomeric forms and therefore represent original molecular models for tris-grafted and bis-grafted isolated (V═O)3+ species dispersed onto silica. Their ability as precatalysts for the epoxidation of cyclic olefins and allylic alcohols with tert-butyl hydroperoxide (TBHP) has been studied. The results suggested that a confined tris-grafted species, such as 3 or 3?, does not act as an efficient catalyst whereas a more labile bis-grafted species, such as 4, does. To gain a better understanding, we have assessed their suitability for ligand exchange with alcohols and TBHP and performed reaction progress kinetic analysis by monitoring the epoxidation of 3-methyl-2-buten-1-ol by 1H and 51V nuclear magnetic resonance.
    Mots-clés : E-POM, POLE 2.


  • G. Izzet, A. Macdonell, C. Rinfray, M. Piot, S. Renaudineau, E. Derat, B. Abécassis, C. Afonso, et A. Proust, « Metal-Directed Self-Assembly of a Polyoxometalate-Based Molecular Triangle: Using Powerful Analytical Tools to Probe the Chemical Structure of Complex Supramolecular Assemblies », Chemistry – A European Journal, vol. 21, nᵒ 52, p. 19010-19015.
    Résumé : A polyoxometalate-based molecular triangle has been synthesized through the metal-driven self-assembly of covalent organic/inorganic hybrid oxo-clusters with remote pyridyl binding sites. The new metallomacrocycle was unambiguously characterized by using a combination of 1H NMR spectroscopy, 2D diffusion NMR spectroscopy (DOSY), electrospray ionization travelling wave ion mobility mass spectrometry (ESI-TWIM-MS), small-angle X-ray scattering (SAXS) and molecular modelling. The collision cross-sections obtained from TWIM-MS and the hydrodynamic radii derived from DOSY are in good agreement with the geometry-optimized structures obtained by using theoretical calculations. Furthermore, SAXS was successfully employed and proved to be a powerful technique for characterizing such large supramolecular assemblies.
    Mots-clés : E-POM, mass spectrometry, NMR spectroscopy, POLE 2, Polyoxometalates, Supramolecular chemistry, X-ray diffraction.


  • L. Leclercq, A. Mouret, S. Renaudineau, V. Schmitt, A. Proust, et V. Nardello-Rataj, « Self-Assembled Polyoxometalates Nanoparticles as Pickering Emulsion Stabilizers », The Journal of Physical Chemistry B, vol. 119, nᵒ 20, p. 6326-6337.
    Résumé : We easily produced a series of polyoxometalate (POM) nanoparticles by taking benefit from electrostatic attractions between various POMs and alkylammonium cations. These self-assembled supramolecular nanoparticles are fully characterized in terms of shape, nanostructure, and physicochemical properties. The nanoparticle differences are discussed on the basis of the chemical composition of the initial POM. Moreover, such particles have the ability to stabilize water-in-oil Pickering emulsions. Using a gel-trapping technique coupled to atomic force microscopy (AFM) observations, we determined their affinity toward oil by the contact angle of adsorbed nanoparticles. We show that the emulsion droplet size and stability can be directly linked to the nanoparticle hydrophobicity, which is tuned by the charge localization and molecular packing of POMs with the ammonium cations. Such particles are of special interest as they open large possibilities for Pickering interfacial catalysis.
    Mots-clés : E-POM, POLE 2.


  • D. Mercier, M. Ben Haddada, M. Huebner, D. Knopp, R. Niessner, M. Salmain, A. Proust, et S. Boujday, « Polyoxometalate nanostructured gold surfaces for sensitive biosensing of benzo[a]pyrene », Sensors and Actuators B: Chemical, vol. 209, p. 770-774.
    Mots-clés : arrays, Benzo[a]pyrene, Biosensor, carbon, CHEMBIO, E-POM, efficiency, immobilization, immunosensors, nanoparticles, Nanostructuration, plasmon resonance, POLE 2, POLE 3, pole3, polycyclic aromatic-hydrocarbons, Polyoxometalate, qcm-d, quartz-crystal microbalance.

  • E. Rousset, D. Chartrand, I. Ciofini, V. Marvaud, et G. S. Hanan, « Red-light-driven photocatalytic hydrogen evolution using a ruthenium quaterpyridine complex », Chemical Communications, vol. 51, nᵒ 45, p. 9261-9264.
    Résumé : A high-temperature, microwave synthesis of [Ru(qpy)(3)](2+) (qpy = 4,4':2',2 '':4 '',4 '''-quaterpyridine) affords the photosensitiser in quantitative yield. The complex produces H-2 photocatalytically in a range extending from the UV region of the spectrum to the red with greater efficiency when compared to [Ru(bpy)(3)](2+).
    Mots-clés : E-POM, electroluminescent devices, h-2 production, homogeneous catalysis, Iridium, Ligands, photoreduction, photosensitizers, POLE 2, polypyridine complexes, visible-light, water reduction.


  • F. Volatron, J. - M. Noël, C. Rinfray, P. Decorse, C. Combellas, F. Kanoufi, et A. Proust, « Electron transfer properties of a monolayer of hybrid polyoxometalates on silicon », Journal of Materials Chemistry, vol. 3, nᵒ 24, p. 6266-6275.


  • Y. Wang, P. - A. Deyris, T. Caneque, F. Blanchard, Y. Li, F. Bigi, R. Maggi, S. Blanchard, G. Maestri, et M. Malacria, « A Simple Synthesis of Triangular All-Metal Aromatics Allowing Access to Isolobal All-Metal Heteroaromatics », Chemistry – A European Journal, vol. 21, nᵒ 35, p. 12271-12274.
    Résumé : A simple synthetic method allows the one-pot assembly of C3-symmetric, 44-core-valence-electron, triangular Pd or Pt clusters and their heterobimetallic mixed Pd/Pt analogues. These mixed metal complexes are the first examples of stable triangular all-metal heteroaromatics. In contrast to traditional heteroaromatic molecules formed combining main-group elements, they actually retain structural and electronic features of their homonuclear analogues.
    Mots-clés : aromaticity, E-POM, EPOM, ERMMES, Heterocycles, MACO, POLE 1, POLE 2.

2014



  • S. Blanchard, L. Fensterbank, G. Gontard, E. Lacôte, G. Maestri, et M. Malacria, « Synthesis of Triangular Tripalladium Cations as Noble-Metal Analogues of the Cyclopropenyl Cation », Angewandte Chemie International Edition, vol. 53, nᵒ 7, p. 1987-1991.
    Résumé : The first C3-symmetric 44-core-valence-electron triangular palladium clusters, [{(SAr′)(PAr3)Pd}3]+, have been synthesized by activation of the CS bond of isothioureas. Owing to delocalized metal–metal bonding, these stable complexes are the first noble-metal analogues of the π-aromatic cyclopropenyl cation [C3H3]+, with their all-metal aromaticity involving d-type atomic orbitals.
    Mots-clés : aromaticity, cluster compounds, COS, E-POM, MACO, metallacycles, metal–metal interactions, Palladium, POLE 1, POLE 2, POM.
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  • C. Bosch-Navarro, B. Matt, G. Izzet, C. Romero-Nieto, K. Dirian, A. Raya, S. I. Molina, A. Proust, D. M. Guldi, C. Marti-Gastaldo, et E. Coronado, « Charge transfer interactions in self-assembled single walled carbon nanotubes/Dawson-Wells polyoxometalate hybrids », Chemical Science, vol. 5, nᵒ 11, p. 4346-4354.
    Résumé : We demonstrate the success in self-assembling pyrene-modified Dawson-Wells-type polyoxometalates (POMs) with single walled carbon nanotubes (SWCNTs) by means of pi-pi interactions. In this context, the immobilization of POMs onto SWCNTs is corroborated by aberration-corrected high-resolution electron microscopy, thermogravimetric analysis, and Raman spectroscopy. From steady-state and time-resolved photophysical techniques we derived evidence for mutual interactions between SWCNTs and POMs in the excited states. The latter are the inception to a charge transfer from the SWCNTs to the POMs. Our results corroborate the suitability of POM-SWCNTs assemblies for photoactive molecular devices.
    Mots-clés : catalyst, E-POM, electron-transfer, Keggin, light, magnets, molecular cluster batteries, platforms, POLE 2, post-functionalization, water oxidation.

  • B. Doistau, A. Tron, S. A. Denisov, G. Jonusauskas, N. D. McClenaghan, G. Gontard, V. Marvaud, B. Hasenknopf, et G. Vives, « Terpy(Pt-salphen)2 Switchable Luminescent Molecular Tweezers. », Chemistry A European Journal, vol. 20, nᵒ 48, p. 15799-807.
    Résumé : The design and synthesis of switchable molecular tweezers based on a luminescent terpy(Pt-salphen)2 (1; terpy=terpyridine) complex is reported. Upon metal coordination, the tweezers can switch from an open "W"-shaped conformation to a closed "U"-shaped form that is adapted for selective recognition of cations. Closing of the tweezers by metal coordination (M=Zn(2+) , Cu(2+) , Pb(2+) , Fe(2+) , Hg(2+) ) was monitored by (1) H NMR and/or UV/Vis titrations. During the titration, exclusive formation of the 1:1 complex [M(1)] was observed, without appearance of an intermediate 1:2 complex [M(1)2 ]. The crystallographic structure of the 1:1 complex was obtained with Pb(2+) and showed a distorted helical structure. Selective intercalation of Hg(2+) cations by the closed "U" form was observed. The tweezers were reopened by selective metal decoordination of the terpyridine ligand by using tris(2-aminoethyl)amine (tren) as a competitive ligand without modification of the Pt-salphen complex. Detailed photophysical studies were performed on the open and closed tweezers. Structured emission was observed in the open form from the Pt-salphen moieties, with a high quantum yield and a long lifetime. The emission is slightly modified upon closing with 1 equivalent of Zn(2+) or Hg(2+) , whereas a dramatic quenching was obtained upon intercalation of additional Hg(2+) . 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Mots-clés : E-POM, GOBS, POLE 2, POLE 3.

  • J. W. Fredy, J. Scelle, A. Guenet, E. Morel, S. A. de Beaumais, M. Menand, V. Marvaud, C. S. Bonnet, E. Toth, M. Sollogoub, G. Vives, et B. Hasenknopf, « Cyclodextrin Polyrotaxanes as a Highly Modular Platform for the Development of Imaging Agents », Chemistry-a European Journal, vol. 20, nᵒ 35, p. 10915-10920.
    Résumé : Selectively functionalized cyclodextrins with a bodipy fluorescent tag or Gd3+ complex were synthetized and threaded onto a polyammonium chain to form polyrotaxanes. This modular supramolecular assembly makes an ideal platform for bimodal (fluorescent and MRI) imaging applications.
    Mots-clés : alpha,omega-diaminoalkanes, alpha-cyclodextrin, beta-cyclodextrin, bimodal imaging, complexes, Cyclodextrin, drug-delivery, E-POM, GOBS, mri contrast agents, NMR, POLE 2, POLE 3, polyrotaxane, quantum dots, silica nanoparticles, soluble bodipy derivatives.
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  • J. Jacquet, E. Salanouve, M. Orio, H. Vezin, S. Blanchard, E. Derat, M. D. - E. Murr, et L. Fensterbank, « Iminosemiquinone radical ligands enable access to a well-defined redox-active CuII–CF3 complex », Chemical Communications, vol. 50, nᵒ 72, p. 10394-10397.
    Résumé : The reaction of a copper complex bearing iminosemiquinone ligands with a CF3+ source provides an unprecedented CuII–CF3 complex through ligand-based oxidation. Reactivity of this complex leads to nucleophilic trifluoromethylation of the ligand, suggesting an electronic interplay that results in a formal umpolung of the initial CF3+.
    Mots-clés : E-POM, MACO, POLE 1, POLE 2.
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  • V. Jallet, G. Guillemot, J. Lai, P. Bauduin, V. Nardello-Rataj, et A. Proust, « Covalent amphiphilic polyoxometalates for the design of biphasic microemulsion systems », Chemical Communications, vol. 50, nᵒ 50, p. 6610-6612.
    Résumé : Covalent amphiphilic polyoxometalates generated from alkyl-phosphonic acids have been synthesized, characterized and monitored by multinuclear NMR spectroscopy. Among them, K3H[gamma-SiW10O36(C12H25PO)(2)] has been successfully used as a surfactant for the stabilization of a Winsor I type microemulsion system.
    Mots-clés : Catalysis, complex, desulfurization, E-POM, Functionalization, head groups, hydrogen-peroxide, nanostructures, oxidation, POLE 2, surfactants, thin-films.

  • B. Keita, A. Proust, P. Gouzerh, et U. Kortz, « Special Issue: Nadjo - Contant Memorial Issue Foreword », Journal of Cluster Science, vol. 25, nᵒ 3, p. 681-685.


  • E. S. Koumousi, I. - R. Jeon, Q. Gao, P. Dechambenoit, D. N. Woodruff, P. Merzeau, L. Buisson, X. Jia, D. Li, F. Volatron, C. Mathonière, et R. Clérac, « Metal-to-Metal Electron Transfer in Co/Fe Prussian Blue Molecular Analogues: The Ultimate Miniaturization », Journal of the American Chemical Society, vol. 136, nᵒ 44, p. 15461-15464.
    Résumé : Co/Fe Prussian Blue analogues are known to display both thermally and light induced electron transfer attributed to the switching between diamagnetic {FeIILS(μ-CN)CoIIILS} and paramagnetic {FeIIILS(μ-CN)CoIIHS} pairs (LS = low spin; HS = high spin). In this work, a dinuclear cyanido-bridged Co/Fe complex, the smallest {Fe(μ-CN)Co} moiety at the origin of the remarkable physical properties of these systems, has been designed by a rational building-block approach. Combined structural, spectroscopic, magnetic and photomagnetic studies reveal that a metal-to-metal electron transfer that can be triggered in solid state by light, temperature and solvent contents, is observed for the first time in a dinuclear complex.
    Mots-clés : E-POM, POLE 2.


  • K. Kuepper, M. Neumann, A. J. M. Al-Karawi, A. Ghosh, S. Walleck, T. Glaser, P. Gouzerh, et A. Müller, « Immediate Formation/Precipitation of Icosahedrally Structured Iron–Molybdenum Mixed Oxides from Solutions Upon Mixing Simple Iron(III) and Molybdate Salts », Journal of Cluster Science, vol. 25, nᵒ 1, p. 301-311.
    Résumé : The present investigation refers to nanostructured mixed metal oxides—more specifically to iron–molybdenum oxides most simply obtained by addition of iron(III) chloride to an aqueous solution of sodium molybdate acidified with acetic acid. The immediately obtained yellow non-crystalline solid consists of highly symmetrical icosahedral {Mo72Fe30} motifs which is proven by IR, Raman, 57Fe Mössbauer and XP spectra. This remarkable result is obtained in spite of the immediate precipitation of the mentioned compound and even from an inhomogeneous mixture of the educts. This again proves the high formation tendency of spherical clusters. The procedure offers in principle the option to encapsulate species present in solution.
    Mots-clés : Catalysis, E-POM, Icosahedral motifs, Inorganic Chemistry, iron, Keplerates, Mixed metal oxides, molybdenum, Physical Chemistry, POLE 2, POM.


  • M. Alaaeddine, Q. Zhu, D. Fichou, G. Izzet, J.E. Rault, N. Barrett, A. Proust, et L. Tortech, « Enhancement of photovoltaic efficiency by insertion of a polyoxometalate layer at the anode of an organic solar cell », Inorg. Chem. Frontiers, vol. 1, nᵒ 9, p. 682-688.
    Résumé : In this article the Wells–Dawson polyoxometalate K6[P2W18O62] is grown as an interfacial layer between indium tin oxide and bulk heterojunction of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The structure of the POM layers depends on the thickness and shows a highly anisotropic surface organization. The films have been characterized by atomic force microscopy and X-ray photoelectron spectroscopy (XPS) to gain insight into their macroscopic organization and better understand their electronic properties. Then, they were put at the anodic interface of a P3HT:PCBM organic solar cell and characterized on an optical bench. The photovoltaic efficiency is discussed in terms of the benefit of the polyoxometalate at the anodic interface of an organic photovoltaic cell.
    Mots-clés : E-POM, NASCO, POLE 2.


  • M. Ménand, S. Adam de Beaumais, L. - M. Chamoreau, E. Derat, S. Blanchard, Y. Zhang, L. Bouteiller, et M. Sollogoub, « Solid-State Hierarchical Cyclodextrin-Based Supramolecular Polymer Constructed by Primary, Secondary, and Tertiary Azido Interactions », Angewandte Chemie International Edition, vol. 53, nᵒ 28, p. 7238-7242.
    Mots-clés : Azides, Cyclodextrins, E-POM, GOBS, inclusion compounds, MACO, POLE 1, POLE 2, POLE 3, POLE 4, POLYMERES, supramolecular polymers.
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  • A. Müller et P. Gouzerh, « Capsules with Highly Active Pores and Interiors: Versatile Platforms at the Nanoscale », Chemistry - A European Journal, vol. 20, nᵒ 17, p. 4862-4873.

  • C. Rinfray, S. Renaudineau, G. Izzet, et A. Proust, « A covalent polyoxomolybdate-based hybrid with remarkable electron reservoir properties », Chemical Communications, vol. 50, nᵒ 62, p. 8575-8577.
    Résumé : A new polyoxomolybdate-based hybrid platform TBA(4)[PMo11O39-{Sn(p-C6H4I)}] is reported. The presence of a post-functionalisable iodo-aryl moiety allows the grafting of a ferrocenyl moiety onto the POM. The electrochemical characterisation shows the effect of molybdenum on the electron reservoir properties of POM-based hybrids, which are further enhanced upon the addition of an acid.
    Mots-clés : chemistry, clusters, derivatives, E-POM, Keggin, platforms, POLE 2, polymers, polyoxometalates synthesis, polyoxotungstates, post-functionalization, Ruthenium.


  • E. Salanouve, G. Bouzemame, S. Blanchard, E. Derat, M. Desage-El Murr, et L. Fensterbank, « Tandem C-H Activation/Arylation Catalyzed by Low-Valent Iron Complexes with Bisiminopyridine Ligands », Chemistry – A European Journal, vol. 20, nᵒ 16, p. 4754-4761.
    Résumé : Tandem CH activation/arylation between unactivated arenes and aryl halides catalyzed by iron complexes that bear redox-active non-innocent bisiminopyridine ligands is reported. Similar reactions catalyzed by first-row transition metals have been shown to involve substrate-based aryl radicals, whereas our catalytic system likely involves ligand-centered radicals. Preliminary mechanistic investigations based on spectroscopic and reactivity studies, in conjunction with DFT calculations, led us to propose that the reaction could proceed through an inner-sphere CH activation pathway, which is rarely observed in the case of iron complexes. This bielectronic noble-metal-like behavior could be sustained by the redox-active non-innocent bisiminopyridine ligands.
    Mots-clés : aryl halides, bis(imino)pyridine iron, bond activation, Catalysis, CH activation, cross-coupling reactions, CH activation, direct arylation, direct functionalization, E-POM, ethylene polymerization catalysts, E_POM, IR spectroscopy, iron, MACO, POLE 1, POLE 2, POM, redox-active ligands, reductive elimination, unactivated arenes.
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  • A. - R. Tomsa, Y. Li, S. Blanchard, P. Herson, K. Boubekeur, P. Gouzerh, et A. Proust, « Oxo-Centered Trinuclear Chromium(III) Complexes with Both Carboxylate and Amidoximate Ligands », Journal of Cluster Science, vol. 25, nᵒ 3, p. 825-838.
    Mots-clés : Amidoximes, Carboxylate, Catalysis, Chromium, E-POM, Inorganic Chemistry, Magnetism, Physical Chemistry, POLE 2, POM, structure.

  • R. Villanneau, A. Roucoux, P. Beaunier, D. Brouri, et A. Proust, « Simple procedure for vacant POM-stabilized palladium (0) nanoparticles in water: structural and dispersive effects of lacunary polyoxometalates », Rsc Advances, vol. 4, nᵒ 50, p. 26491-26498.
    Résumé : Metallic palladium nanoparticles have been generated by hydrogenation with H-2 of solutions of several non organometallic Pd-II-derivatives of heteropolytungstates, at ambient temperature and atmospheric pressure. These nanoparticles have been characterized by various techniques: P-31 NMR and Raman spectroscopy, TEM (including cryogenic techniques), DLS, EDX and XPS. The present strategy ruled out the presence of ligands and/or stabilizing agents other than the lacunary polyoxometalates (POMs) used. This allows the evaluation of the true efficiency of the different vacant POMs for the stabilization of the nanoparticles.
    Mots-clés : E-POM, gold nanoparticles, hydrogen-peroxide, Keggin, metal nanoparticles, molecular-oxygen, nanocluster formation, oxidation, pd nanoparticles, photocatalytic reduction, POLE 2, recyclable catalysts.


  • M. Yaqub, J. J. Walsh, T. E. Keyes, A. Proust, C. Rinfray, G. Izzet, T. McCormac, et R. J. Forster, « Electron Transfer to Covalently Immobilized Keggin Polyoxotungstates on Gold », Langmuir, vol. 30, nᵒ 15, p. 4509-4516.

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