B. Chaudret

University of Toulouse, Tolosa de Llenguadoc, Midi-Pyrénées, France

Are you B. Chaudret?

Claim your profile

Publications (205)719.42 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Ru nanoparticles (RuNPs) stabilized by non-isolable chiral N-heterocyclic carbenes (NHCs), namely SIDPhNp ((4S,5S)-1,3-di(naphthalen-1-yl)-4,5-diphenylimidazolidine) and SIPhOH ((S)-3-((1S,2R)-2-hydroxy-1,2-diphenylethyl)-1-((R)-2-hydroxy-1,2-diphenylethyl)-4,5-dihydro-3H-imidazoline), have been synthesized through a new procedure that does not require isolation of the free carbenes. The obtained RuNPs have been characterized by state-of-the-art techniques and their surface chemistry has been investigated by FTIR and solid-state MAS NMR upon the coordination of CO, which indicated the presence of free and reactive Ru sites. Their catalytic activity has been tested in various hydrogenation reactions involving competition between different sites, whereby interesting differences in selectivity were observed, but no enantioselectivity.
    No preview · Article · Oct 2015 · Chemistry - A European Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: P-H functional transition-metal complexes were synthesized without using hazardous PH3 gas in good yields by photolysis of the transition-metal carbonyl complexes M(CO)6-x (M = Cr, W, Fe; x = 0, 1) in tetrahydrofuran followed by reaction with P2(SiMe3)4 and subsequent methanolysis to give the bridging complexes [(CO)xM(μ-PH2)]2 (M = Fe, x = 3 (1), M = Cr, x = 4 (2a), M = W, x = 4 (2b)). The photolysis of [(CO)4M(μ-PH2)]2 (M = Cr (2a), M = W (2b)) with P(SiMe3)3 was applied followed by methanolysis to synthesize the PH2 bridging transition-metal binuclear complexes with terminal PH3 groups. The products [(CO)4M(μ-PH2)2M(CO)3(PH3)] (M = Cr (3a), M = W (3b)) and [(CO)4W(μ-PH2)2W(CO)2(PH3)2] (4b) were isolated in moderate yield. Another synthetic approach to this type of compounds is the direct photolysis of the complexes [(CO)3M(PH3)3] (M = Cr (5a), M = W (5b)). The products were comprehensively characterized by (31)P NMR and IR spectroscopy as well as by X-ray structural analysis. Additionally, the relevancy of 2a as single source precursor for the synthesis of stoichiometry-controlled CrP nanoparticles has been demonstrated.
    No preview · Article · Oct 2014 · Inorganic Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N-heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high-resolution TEM, and spectroscopic techniques. Solid-state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a 13C–195Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle.
    No preview · Article · Sep 2014 · Angewandte Chemie International Edition
  • [Show abstract] [Hide abstract]
    ABSTRACT: Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N-heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high-resolution TEM, and spectroscopic techniques. Solid-state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a 13C–195Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle.
    No preview · Article · Sep 2014 · Angewandte Chemie
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ultrasmall FeRu bimetallic nanoparticles were prepared by co-decomposition of two organometallic precursors, {Fe[N(Si(CH3)3)2]2}2 and (η4-1,5-cyclooctadiene)(η6-1,3,5-cyclooctatriene)ruthenium(0) (Ru(COD)(COT)), under dihydrogen at 150 °C in mesitylene. A series of FeRu nanoparticles of sizes of approximately 1.8 nm and incorporating different ratios of iron to ruthenium were synthesized by varying the quantity of the ruthenium complex introduced (Fe/Ru=1:1, 1:0.5, 1:0.2, and 1:0.1). FeRu nanoparticles were characterized by TEM, high-resolution TEM, and wide-angle X-ray scattering analyses. Their surface was studied by hydride titration and IR spectroscopy after CO adsorption and their magnetic properties were analyzed by using a superconducting quantum interference device (SQUID). The FeRu nanoparticles were used as catalysts in the hydrogenation of styrene and 2-butanone. The results indicate that the selectivity of the nanoparticle catalysts can be modulated according to their composition and therefore represent a case study on fine-tuning the reactivity of nanocatalysts and adjusting their selectivity in a given reaction.
    No preview · Article · Jun 2014 · ChemCatChem
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three samples of organometallic ruthenium nanoparticles (RuNPs) namely Ru-PVP (PVP=polyvinylpyrrolidone; 1.3 nm), Ru-dppb (dppb= diphenylphosphinobutane; 1.9 nm) and Ru-heptanol-dppb (3.1 nm) were prepared and investigated in a model Fischer-Tropsch Synthesis (FTS) reaction. Our aim was to shed some light on the influence of the metal core size and of the chemical environment at the metal surface on the surface reactivity of these RuNPs through the hydrogenation of CO into hydrocarbons (olefins and paraffins). For that purpose, we used a combination of spectroscopic techniques such as gas phase and solid state NMR, MS and FTIR. The results evidence that the size increase of the metal core does not affect significantly the catalytic properties of the RuNPs since comparable conversion and selectivity are obtained with Ru-dppb and Ru-heptanol-dppb. In the contrary, the stabilizer seems to have a crucial role in directing the catalytic reaction.
    No preview · Article · Jan 2014

  • No preview · Patent · Jan 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phase-pure FeP nanoparticles (NPs) have been synthesized through thermolysis of [(CO)4Fe(PH3)] in the presence of a mixture of hexadecylamine and oleic acid, in mesitylene at 150°C. The single source precursor [(CO)4Fe(PH3)] is prepared by the “one-pot” reaction of [Fe(CO)5] with P(SiMe3)3 and subsequent methanolysis of the reaction mixture. Monitoring the NPs synthesis by IR spectroscopy has allowed the identification of an intermediate species, a binuclear iron complex not carrying organic substituents at the P atoms [(CO)3Fe(-PH2)]2. This complex was prepared separately via the photolysis of [(CO)3Fe(PH3)] and can be considered as the building block to yield iron phosphide material. The nanoparticles have an average diameter of 3.4(0.7) nm and are composed of ca. 55% of organic material coming from ligand sphere. Magnetization measurements reveal an antiferromagnetic behaviour consistent with a phase-pure FeP nanomaterial, the FeP stoichiometry and its purity being further supported by the Mössbauer signature.
    No preview · Article · Oct 2013 · Chemical Communications
  • [Show abstract] [Hide abstract]
    ABSTRACT: The reactivity of ruthenium nanoparticles stabilized by 4-(3-phenylpropyl)pyridine in hydrogen transfer and hydrogenation processes was monitored by NMR spectroscopy. Unsaturated substrates such as styrene, 4-vinylpyridine and 4-phenyl-but-3-en-2-one were used as model molecules to investigate the surface properties of nanoparticles by a combination of NMR studies. Interestingly, the hydrides present at the metallic surface after nanoparticles synthesis are selectively transferred to vinylic groups without reducing the aromatic rings, under dihydrogen-free atmosphere. DOSY and NOE NMR experiments permitted to propose a way of interaction of the organic compounds at the metallic surface. In particular, the coordination of the substrate could be evidenced for 4-vinylpyridine and 4-ethylpyridine but not for styrene derivatives. Graphical Abstract Curved double arrows represent magnetization exchanges. Straight arrows represent adsorption/desorption phenomena.
    No preview · Article · Sep 2013 · Topics in Catalysis

  • No preview · Article · Jul 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: When magnetic nanoparticles (MNPs) are single-domain and magnetically independent, their magnetic properties and the conditions to optimize their efficiency in magnetic hyperthermia applications are now well-understood. However, the influence of magnetic interactions on magnetic hyperthermia properties is still unclear. Here, we report hyperthermia and high-frequency hysteresis loop measurements on a model system consisting of MNPs with the same size but a varying anisotropy, which is an interesting way to tune the relative strength of magnetic interactions. A clear correlation between the MNP anisotropy and the squareness of their hysteresis loop in colloidal solution is observed : the larger the anisotropy, the smaller the squareness. Since low anisotropy MNPs display a squareness higher than the one of magnetically independent nanoparticles, magnetic interactions enhance their heating power in this case. Hysteresis loop calculations of independent and coupled MNPs are compared to experimental results. It is shown that the observed features are a natural consequence of the formation of chains and columns of MNPs during hyperthermia experiments: in these structures, when the MNP magnetocristalline anisotropy is small enough to be dominated by magnetic interactions, the hysteresis loop shape tends to be rectangular, which enhance their efficiency. On the contrary, when MNPs do not form chains and columns, magnetic interactions reduces the hysteresis loop squareness and the efficiency of MNPs compared to independent ones. The present work should improve the understanding and interpretation of magnetic hyperthermia experiments.
    Full-text · Article · Jan 2013 · Physical review. B, Condensed matter
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Various ligands not forming monometallic complexes were used for Ru nanoparticle stabilization, enabling the control of size, shape, and electronic properties. HRMAS NMR spectroscopy allowed us to study surface-bound molecules, evidencing ligand hydrogenation and decomposition of THFduring the RuNP synthesis. Catalysis studies underscore the importance of the nature of the ligands. The RuNPs were tested in the hydrogenation of aromatics, showing very high activities (TOF > 60 000 h–1, 40 bar, 393 K). A pronounced ligand effect was found, and dialkylaryl phosphine ligands gave the fastest catalyst.
    Full-text · Article · Mar 2012 · ACS Catalysis
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The influence of a transverse static magnetic field on the magnetic hyperthermia properties is studied on a system of large-losses ferromagnetic FeCo nanoparticles. The simultaneous measurement of the high-frequency hysteresis loops and of the temperature rise provides an interesting insight into the losses and heating mechanisms. A static magnetic field of only 40 mT is enough to cancel the heating properties of the nanoparticles, a result reproduced using numerical simulations of hysteresis loops. These results cast doubt on the possibility to perform someday magnetic hyperthermia inside a magnetic resonance imaging setup.
    Full-text · Article · Jan 2012 · Applied Physics Letters
  • Source
    M. Zahmakıran · K. Philippot · S. Özkar · B. Chaudret
    [Show abstract] [Hide abstract]
    ABSTRACT: Dimethylamine–borane, (CH3)2NHBH3, has been considered as one of the attractive materials for the efficient storage of hydrogen, which is still one of the key issues in the “Hydrogen Economy”. In a recent communication we have reported the synthesis and characterization of 3-aminopropyltriethoxysilane stabilized ruthenium(0) nanoparticles with the preliminary results for their catalytic performance in the dehydrogenation of dimethylamine–borane at room temperature. Herein, we report a complete work including (i) effect of initial [APTS]/[Ru] molar ratio on both the size and the catalytic activity of ruthenium(0) nanoparticles, (ii) collection of extensive kinetic data under non-MTL conditions depending on the substrate and catalyst concentrations to define the rate law of Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine–borane at room temperature, (iii) determination of activation parameters (Ea, ΔH# and ΔS#) for Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine–borane; (iv) demonstration of the catalytic lifetime of Ru(0)/APTS nanoparticles in the dehydrogenation of dimethylamine–borane at room temperature, (v) testing the bottlability and reusability of Ru(0)/APTS nanocatalyst in the room-temperature dehydrogenation of dimethylamine–borane, (vi) quantitative carbon disulfide (CS2) poisoning experiments to find a corrected TTO and TOF values on a per-active-ruthenium-atom basis, (vii) a summary of extensive literature review for the catalysts tested in the catalytic dehydrogenation of dimethylamine–borane as part of the results and discussions.
    Full-text · Article · Jan 2012 · Dalton Transactions
  • [Show abstract] [Hide abstract]
    ABSTRACT: Progress in the prediction and optimization of the heating of magnetic nanoparticles in an alternating magnetic fi eld is highly desirable for their application in magnetic hyperthermia. Here, a model system consisting of metallic iron nanoparticles with a size ranging from 5.5 to 28 nm is extensively studied. Their properties depend strongly on their size: behaviors typical of single-domain particles in the superparamagnetic regime, in the ferromagnetic regime, and of multi-domain particles are observed. Ferromagnetic single-domain nanoparticles are the best candidates and display the highest specifi c losses reported in the literature so far (11.2 ± 1 mJ g − 1 ). Measurements are analysed using recently demonstrated analytical formulas and numerical simulations of the hysteresis loops. Several features expected theoretically are observed for the fi rst time experimentally: i) the correlation between the nanoparticle diameter and their coercive fi eld, ii) the correlation between the amplitude of the coercive fi eld and the losses, and iii) the variation of the optimal size with the amplitude of the magnetic fi eld. None of these features are predicted by the linear response theory – generally used to interpret hyperthermia experiments – but are a natural consequence of theories deriving from the Stoner–Wohlfarth model; they also appear clearly in numerical simulations. These results open the path to a more accurate description, prediction, and analysis of magnetic hyperthermia.
    No preview · Article · Dec 2011 · Advanced Functional Materials
  • C.amiens · B.chaudret
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanoparticles can be synthesized from metal-organic or organometallic precursors, either by classical thermal decomposition, ultrasound activation, photolysis as well as hydrogenation or hydrolysis reactions. The size, size distribution and more importantly surface state of these nanoparticles are much better controlled than when they are produced by chemical or electrochemical reduction of metal salts. Hence, metal or oxide nanoparticles can be obtained that are suitable for fundamental physics at the nanoscale, especially for magnetic studies. This is currently of particular interest as many applications require systems of still smaller sizes, the properties of which are not yet fully understood.
    No preview · Article · Nov 2011 · Modern Physics Letters B
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work we investigate the magnetic and structural properties of bulk Fe and Fe nanoparticles under pressure with x-ray absorption and emission spectroscopies providing answers to two fundamental questions: (a) the chicken-or-egg problem for the magnetic and structural transitions and (b) magnetism in the high pressure hcp phase. The two transitions, inextricably linked in the bulk, are clearly decoupled in the nanoparticles, with the magnetic collapse preceding the structural transition. Ultrafast x-ray emission spectroscopy detects remnant magnetism, probably antiferromagnetic fluctuations, up to pressures of about 40 GPa in the hcp phase. This could be of direct relevance to the superconductivity in ϵ-Fe [K. Shimizu et al., Nature (London) 412, 316 (2001)] through the existence of a quantum critical point and associated magnetic fluctuations.
    No preview · Article · Jun 2011 · Physical Review Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic hybrid liquid crystal composites have been obtained by thermal decomposition of a cobalt coordination precursor in the presence of a liquid crystal polymer and functional molecules (acid or amine) interacting with the precursor. The final materials contain anisotropic and/or spherical nanoparticles depending on the reaction conditions. They are all mesomorphous and ferromagnetic at ambient temperature. The role of the macromolecular chains as stabilizers of the nanoparticles has been examined. Apart from stabilizing, the polymer chains also prevent the easy access of the functional molecules to the surface of the nanoparticles, necessary to obtain anisotropic objects. Last but not least, the ferromagnetic behavior of the nanoobjects is shown to be enhanced by the presence of the liquid crystal phase: the nano-objects easily align by application of a 3 T magnetic field.
    No preview · Article · May 2011 · Journal of Materials Chemistry
  • L.-M. Lacroix · S. Lachaize · J. Carrey · M. Respaud · B. Chaudret
    [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic nanoparticles (MNP) are of particular interest for hyperthermia of tumors. Their efficiency depends on their size, their surface state and on the material used. Eventhough iron oxide MNP are already tested in clinical trials, metallic iron MNP are promising candidates for the treatment of smaller tumors (metastases). A detailed study of these metallic iron MNP, theoretically more efficient that their oxide counterparts, is reported from their synthesis to their peculiar physical properties. A large variety of MNP has been obtained (spheres from 1.5 to 11 nm, cubes from 7 to 90 nm, stars, porous cubes⋯) and unprecedented heating efficiencies have been measured on ferromagnetic 16 nm cubes (1700 W.g-1Fe).
    No preview · Article · Apr 2011
  • M.R. Axet · K Philippot · B. Chaudret · M. Cabie · S. Giorgio · C.R. Henry

    No preview · Article · Jan 2011

Publication Stats

6k Citations
719.42 Total Impact Points

Institutions

  • 2007-2014
    • University of Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2013
    • Universität Regensburg
      • Institute of Inorganic Chemistry
      Ratisbon, Bavaria, Germany
  • 2011-2012
    • INSA
      Альтамира, Tamaulipas, Mexico
    • Institut National des Sciences Appliquées de Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1984-2011
    • Laboratoire de Chimie de Coordination.
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1991-2010
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1993-2009
    • Institut National Polytechnique de Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1980-2009
    • Paul Sabatier University - Toulouse III
      • • Laboratoire d'Hétérochimie Fondamentale et Appliquée - UMR 5069 - LHFA
      • • Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique - UMR 5623 - IMRCP
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2008
    • Universidad Autónoma de San Luis Potosí
      • Instituto de Física
      San Luis Potosí, San Luis Potosi, Mexico
  • 2001
    • Université de Montpellier
      • Institut Charles Gerhardt Montpellier (ICGM)
      Montpelhièr, Languedoc-Roussillon, France