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Accueil > Les équipes > Equipe de Recherche en Matériaux Moléculaires et Spectroscopies (ERMMES) > Publications

Publications

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2017

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2015



  • M. Castellano, R. Ruiz-García, J. Cano, J. Ferrando-Soria, E. Pardo, F. R. Fortea-Pérez, S. - E. Stiriba, W. P. Barros, H. O. Stumpf, L. Cañadillas-Delgado, J. Pasán, C. Ruiz-Pérez, G. de Munno, D. Armentano, Y. Journaux, F. Lloret, et M. Julve, « Metallosupramolecular approach toward multifunctional magnetic devices for molecular spintronics », Coordination Chemistry Reviews, vol. 303, p. 110-138.
    Résumé : The work presented in this review constitutes a successful extension of our group's research on the chemistry and physics of dinuclear copper(II) metallacyclophanes with aromatic polyoxalamide ligands. The design and synthesis of metallacyclic complexes that contain multiple electro- and photoactive (either metal- or ligand-based) spin carriers and the study of their spectroscopic and magnetic properties as well as their redox and photochemical activity are of large interest in the multidisciplinary field of metallosupramolecular chemistry. In doing this, a ligand design approach has been followed which is based on the copper(II)-mediated self-assembly of bis(oxamato) bridging ligands possessing potentially electro- and photoactive, extended π-conjugated aromatic spacers. This strategy benefits from the inherent physical and chemical properties of aromatic organic molecules by functionalizing them with two oxamato donor groups to get dinucleating ligands that are then able to self-assemble with square planar CuII ions affording the targeted oxamato-based dicopper(II) metallacyclophanes. The organic functionalization in this new class of metallacyclic systems constitutes a unique example of ligand design for the supramolecular control of the structure and magnetic properties, as well as the electro- and photochemical activities. This novel class of oxamato-based dicopper(II) metallacyclophanes provides excellent models for the fundamental study on through-ligand long-distance and redox- or photo-triggered electron exchange phenomena, which are two central topics in molecular magnetism and molecular electronics. Using these simple dinuclear metallacyclic complexes as dynamic chemical systems to perform specific and selective tasks under the control of an external (electro- and/or photochemical) stimulus that switches “ON” and “OFF” their electronic (optical and/or magnetic) properties may have an enormous impact in several domains of molecular nanoscience. Hence, oxamato-based dicopper(II) metallacyclophanes appear as very promising candidates to get multifunctional magnetic devices controlling and facilitating the spin communication (“molecular magnetic couplers” and “molecular magnetic wires”) or exhibiting charge storage (“molecular magnetic capacitors”) and bistable spin behavior (“molecular magnetic rectifiers” and “molecular magnetic switches”) for potential applications in information processing and storage in the emerging areas of molecular spintronics and quantum computing. Moreover, because of the potential high affinity for a variety of metal surfaces through the free carbonyl-oxygen atoms of the oxamate groups, they are very appealing candidates for the study of coherent electron transport through single molecules.
    Mots-clés : Electrochemistry, ERMMES, Ligand design, Magnetochemistry, Metallacyclic complexes, Metallosupramolecular chemistry, photochemistry, POLE 2.


  • D. de Bellefeuille, M. Orio, A. L. Barra, A. Aukauloo, Y. Journaux, C. Philouze, X. Ottenwaelder, et F. Thomas, « Redox Noninnocence of the Bridge in Copper(II) Salophen and Bis(oxamato) Complexes », Inorganic Chemistry, vol. 54, nᵒ 18, p. 9013-9026.
    Résumé : Two square-planar copper(II) complexes of 1,2-bis(2-hydroxy-3,5-di-tert-butylbenzimino)-4,5-bis-(dimethylamino)benzene (1) and N-[4,5-bis(dimethylamino)-2-(oxalylamino)benzene]oxamate (2(2-)) were prepared. The crystal structures of the proligands H2L1 and Et2H2L2, as well as the corresponding complexes, are reported. The proligands each display a one-electron-oxidation wave, which is assigned to oxidation of the bis(dimethylamino)benzene moiety into a pi radical. Complexes 1 and 2(2-) exhibit reversible one-electron-oxidation waves in their cyclic voltammograms (E-1/2(1) = 0.14 and E-1/2(2) = 0.31 V for 1 and E-1/2(1) = 0.47 V vs Fc(+)/Fc for 2(2-)). The first process corresponds to oxidation of the bis(dimethylamino)benzene central ring into a pi radical, while the second process for 1 is ascribed to oxidation of the pi radical into an alpha-diiminoquinone. The one-electron-oxidized species 1(+) and 2(-) exhibit intense visible near-IR absorptions, which are diagnostic of pi radicals. They display a triplet signal in their electron paramagnetic resonance spectra, which stem from magnetic coupling between the ligand-radical spin and the copper(II) spin. The zero-field-splitting parameters are larger for 2(-) than 1(+) because of greater delocalization of the spin density onto the coordinated amidato N atoms. Density functional theory calculations support a pi-radical nature of the one-electron-oxidized complexes, as well as S = 1 ground spin states. The electrogenerated 1(2+) comprises a closed-shell diiminoquinone ligand coordinated to a copper(II) metal center. Both 1 and 2 catalyze the aerobic oxidation of benzyl alcohol, albeit with different yields.
    Mots-clés : ERMMES, POLE 2.


  • T. Grancha, M. Mon, F. Lloret, J. Ferrando-Soria, Y. Journaux, J. Pasan, et E. Pardo, « Double Interpenetration in a Chiral Three-Dimensional Magnet with a (10,3)-a Structure », Inorganic Chemistry, vol. 54, nᵒ 18, p. 8890-8892.
    Résumé : A unique chiral three-dimensional magnet with an overall racemic double-interpenetrated (10,3)-a structure of the formula [(S)-(1-PhEt)-Me3N](4)[Mn4Cu6(Et(2)pma)(12)] (DMSO)(3)]center dot 3DMS center dot 5H(2)O (1; Et(2)pma = N-2,6-diethylphenyloxamate) has been synthesized by the self-assembly of a mononuclear copper(II) complex acting as a metalloligand toward Mn-II ions in the presence of a chiral cationic auxiliary, constituting the first oxamato-based chiral coordination polymer exhibiting long-range magnetic ordering.
    Mots-clés : ERMMES, POLE 2.

  • A. Paquirissamy, A. R. Ruyack, A. Mondal, Y. Li, R. Lescouezec, C. Chaneac, et B. Fleury, « Versatile nano-platforms for hybrid systems: expressing spin-transition behavior on nanoparticles », Journal of Materials Chemistry C, vol. 3, nᵒ 14, p. 3350-3355.
    Résumé : The aim of this paper is to demonstrate the possibility of expressing molecular magnetic phenomena on hybrid nano-particles. The advantage of such composite materials is their wonderful versatility, in terms of choice of molecular compounds to be grafted on, and in terms of possibilities for integration in devices. As a first example, we designed a composite made of silica nanoparticles as cores on which Fe(II) coordination complexes displaying spin-crossover (SCO) phenomenon have been grafted in three steps involving the silanization of the SiO2 core, the anchoring of bis(1-methylimidazolyl)-type ligands and at last the coordination of octahedral Fe(II) complexes at the surface of the nanoparticles. This step-by-step procedure enables an adequate coverage of the Fe(II) complexes at the surface of the nanoparticles that allows for the appearance of the spin-transition (ST) behavior at a level detectable by SQUID magnetometry. These tailor-made particles can thus be considered as nanometric switchable units.
    Mots-clés : COMPLEXES, COOPERATIVITY, CROSSOVER, ELECTRON-MICROSCOPY, ERMMES, INORGANIC, IRON CYANIDE, MAGNETIC-PROPERTIES, MEMORY DEVICES, POLE 2, ROOM-TEMPERATURE, SEQUENTIAL GROWTH, SURFACES.


  • Y. Prado, N. Daffe, A. Michel, T. Georgelin, N. Yaacoub, J. M. Greneche, F. Choueikani, E. Otero, P. Ohresser, M. A. Arrio, C. Cartier-dit-Moulin, P. Sainctavit, B. Fleury, V. Dupuis, L. Lisnard, et J. Fresnais, « Enhancing the magnetic anisotropy of maghemite nanoparticles via the surface coordination of molecular complexes », Nature Communications, vol. 6.
    Résumé : Superparamagnetic nanoparticles are promising objects for data storage or medical applications. In the smallest-and more attractive-systems, the properties are governed by the magnetic anisotropy. Here we report a molecule-based synthetic strategy to enhance this anisotropy in sub-10-nm nanoparticles. It consists of the fabrication of composite materials where anisotropic molecular complexes are coordinated to the surface of the nanoparticles. Reacting 5 nm gamma-Fe2O3 nanoparticles with the [Co-II(TPMA)Cl-2] complex (TPMA: tris(2-pyridylmethyl) amine) leads to the desired composite materials and the characterization of the functionalized nanoparticles evidences the successful coordination-without nanoparticle aggregation and without complex dissociation-of the molecular complexes to the nanoparticles surface. Magnetic measurements indicate the significant enhancement of the anisotropy in the final objects. Indeed, the functionalized nanoparticles show a threefold increase of the blocking temperature and a coercive field increased by one order of magnitude.
    Mots-clés : ERMMES, POLE 2.


  • 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.


  • H. Yang, S. Masse, M. Rouelle, E. Aubry, Y. Li, C. Roux, Y. Journaux, L. Li, et T. Coradin, « Magnetically recoverable iron oxide–hydroxyapatite nanocomposites for lead removal », International Journal of Environmental Science and Technology, vol. 12, nᵒ 4, p. 1173-1182.
    Résumé : Magnetite–hydroxyapatite nanocomposites were prepared by in situ precipitation of the calcium phosphate phase in an iron oxide colloidal suspension. Homogeneous magnetic powders were obtained with iron oxide content up to 50 wt%, without perturbation of the magnetite structure nor formation of additional calcium phosphates. The surface area of the composite powder was significantly increased after incorporation of magnetite due to the better apatite particle dispersion. This results in an increased available reactive surface, favoring lead sorption and hydroxypyromorphite precipitation, both leading to an enhanced lead removal capacity of the composite materials. The magnetic properties of magnetite nanocrystals were preserved upon association with hydroxyapatite. Full recovery of the composite powder after lead removal could be achieved using a simple magnet at a relatively low iron oxide content (20 wt%). This indicates a strong interaction between hydroxyapatite and magnetite particles within the composite powder. The procedure is simple, easily scalable and involves only environmental friendly materials.
    Mots-clés : ERMMES, POLE 2.

2014


  • M. Castellano, W. P. Barros, A. Acosta, M. Julve, F. Lloret, Y. Li, Y. Journaux, G. De Munno, D. Armentano, R. Ruiz-Garcia, et J. Cano, « Dicopper(II) Anthraquinophanes as Multielectron Reservoirs for Oxidation and Reduction: A Joint Experimental and Theoretical Study », Chemistry-a European Journal, vol. 20, nᵒ 43, p. 13965-13975.
    Résumé : Two new dinuclear copper(II) metallacyclophanes with 1,4-disubstituted 9,10-anthraquinonebis(oxamate) bridging ligands are reported that can reversibly take and release electrons at the redox-active ligand and metal sites, respectively, to give the corresponding mono-and bis(semiquinonate and/or catecholate) Cu-2(II) species and mixedvalent Cu-II/Cu-III and high-valent Cu-2(III) ones. Density functional calculations allow us to give further insights on the dual ligand-and metal-based character of the redox processes in this novel family of antiferromagnetically coupled dicopper(II) anthraquinophanes. This unique ability for charge storage could be the basis for the development of new kinds of molecular spintronic devices, referred to as molecular magnetic capacitors (MMCs).
    Mots-clés : chemistry, clusters, Copper, density functional calculations, electron-transfer, ERMMES, ligand, Magnetic properties, molecular electronics, POLE 2, quantum cellular-automata, quinones, redox properties, transition-metal-complexes.

  • B. Matt, K. M. Pondman, S. J. Asshoff, B. ten Haken, B. Fleury, et N. Katsonis, « Soft Magnets from the Self-Organization of Magnetic Nanoparticles in Twisted Liquid Crystals », Angewandte Chemie-International Edition, vol. 53, nᵒ 46, p. 12446-12450.
    Résumé : Organizing magnetic nanoparticles into long-range and dynamic assemblies would not only provide new insights into physical phenomena but also open opportunities for a wide spectrum of applications. In particular, a major challenge consists of the development of nanoparticle-based materials for which the remnant magnetization and coercive field can be controlled at room temperature. Our approach consists of promoting the self-organization of magnetic nanoparticles in liquid crystals (LCs). Using liquid crystals as organizing templates allows us to envision the design of tunable self-assemblies of magnetic nanoparticles, because liquid crystals are known to reorganize under a variety of external stimuli. Herein, we show that twisted liquid crystals can be used as efficient anisotropic templates for superparamagnetic nanoparticles and demonstrate the formation of hybrid soft magnets at room temperature.
    Mots-clés : coatings, ERMMES, gold nanoparticles, liquid crystals, nanoparticles, POLE 2, polymer networks, Self-assembly, smart materials.

  • A. Mondal, Y. Li, L. - M. Chamoreau, M. Seuleiman, L. Rechignat, A. Bousseksou, M. - L. Boillot, et R. Lescouezec, « Photo- and thermo-induced spin crossover in a cyanide-bridged {(Mo2Fe2II)-Fe-V} rhombus molecule », Chemical Communications, vol. 50, nᵒ 22, p. 2893-2895.
    Résumé : The self-assembly of [Mo-V(CN)(8)](3-) and [Fe-II(bik)(2)(S)(2)](2+) affords a cyanide-bridged {(Mo2Fe2II)-Fe-V} rhombus molecule that shows photo-magnetic effect under laser light irradiation at low temperature and exhibits thermo-induced spin crossover near ambient temperature.
    Mots-clés : behavior, complexes, crystal, ERMMES, fe, magnet, mo, ni, photoinduced magnetization, POLE 2.

  • R. Tirfoin, L. - M. Chamoreau, Y. Li, B. Fleury, L. Lisnard, et Y. Journaux, « Synthesis, structure and magnetic properties of phenylhydroxamate-based coordination clusters », Dalton Transactions, vol. 43, nᵒ 44, p. 16805-16817.
    Résumé : The strategic recombination of preformed coordination clusters in the presence of polymodal bridging ligands has successfully led to the characterisation of five new compounds of structural and magnetic interest. Indeed using the dinuclear complex [M-2(H2O)(piv)(4)(Hpiv)(4)] (M = Co, Ni; Hpiv = pivalic acid) as starting material and reacting it with phenylhydroxamic acid (H(2)pha) has yielded the four tetrametallic coordination clusters [Co-4(Hpha)(2)(piv)(6)(Hpiv)(4)] (1), [Ni-4(Hpha)(2)(piv)(6)(Hpiv)(2)(DMF)(2)] (2), [Co-4(Hpha)(2)(piv)(6)(EtOH)(2)(H2O)(2)] (3), [Ni-4(Hpha)(2)(piv)(6)(EtOH)(2)(H2O)(2)] (4) and the hexanuclear complex [Co-6(Hpha)(4)(piv)(8)(EtOH)(2)]center dot EtOH (5). All the compounds have been structurally characterised revealing a particular binding mode for the hydroxamate ligand. The study of their magnetic properties has been performed and the modelling of these properties has been done using the appropriate hamiltonians for each compound. The experimental data and their modelling show non-zero spin ground states for compounds 4 and 5.
    Mots-clés : ERMMES, POLE 2.

2013



  • N. Baumgärtel, A. Flambard, F. H. Köhler, et R. Lescouëzec, « Paramagnetic Hexacyanometalates. The Diversity of Spin Distribution Studied by <sup>13</sup> C and <sup>15</sup> N MAS NMR Spectroscopy », Inorganic Chemistry, vol. 52, nᵒ 21, p. 12634-12644.


  • M. Castellano, F. R. Fortea-Pérez, A. Bentama, S. - E. Stiriba, M. Julve, F. Lloret, G. De Munno, D. Armentano, Y. Li, R. Ruiz-García, et J. Cano, « Dicopper(II) Metallacyclophanes with Oligo(p-phenylene-ethynylene) Spacers: Experimental Foundations and Theoretical Predictions on Potential Molecular Magnetic Wires », Inorganic Chemistry, vol. 52, nᵒ 13, p. 7645-7657.
    Résumé : Two novel double-stranded dicopper(II) metallacyclophanes of formula (nBu4N)4[Cu2(dpeba)2]·4MeOH·2Et2O (1) and (nBu4N)4[Cu2(tpeba)2]·12H2O (2) have been prepared by the CuII-mediated self-assembly of the rigid (?rod-like?) bridging ligands N,N?-4,4?-diphenylethynebis(oxamate) (dpeba) and N,N?-1,4-di(4-phenylethynyl)phenylenebis(oxamate) (tpeba), respectively. Single crystal X-ray diffraction analysis of 1 confirms the presence of a dicopper(II)tetraaza[3.3]4,4?-diphenylethynophane metallacyclic structure featuring a very long intermetallic distance between the two square planar CuII ions [r = 14.95(1) Å]. The overall parallel-displaced π-stacked conformation of the two nearly planar para substituted diphenylethyne spacers [dihedral angle (?) of 7.8(1)°] leads to important deviations from the perpendicular orientation of the copper mean basal planes with respect to the facing benzene planes [dihedral angles (?) of 56.4(1) and 58.4(1)°]. X-band EPR spectra together with variable-temperature magnetic susceptibility and variable-field magnetization measurements of 1 and 2, both in solution and in the solid state, show the occurrence of a non-negligible, moderate to weak intramolecular antiferromagnetic coupling [?J = 3.9?4.1 (1) and 0.5?0.9 cm?1 (2); H = ?JS1·S2 with S1 = S2 = SCu = 1/2]. Density functional calculations on the BS singlet (S = 0) and triplet (S = 1) spin states of the model complexes 1 and 2 with an ideal orthogonal molecular geometry (? = 0° and ? = 90°) support the occurrence of a spin polarization mechanism for the propagation of the exchange interaction between the two unpaired electrons occupying the dxy orbital of each square planar CuII ion through the predominantly π-type orbital pathway of the double p-diphenylethyne (1) and di(phenylethynyl)phenylene spacers (2). Time-dependent density functional calculations reproduce the observed bathochromic shift of the main intraligand (IL) π?π* transition in the electronic absorption spectra of 1 and 2 [?1 = 308 (1) and 316 nm (2)]. In the series of orthogonal model complexes 1?5 with linear oligo(p-phenylene-ethynylene) (OPE) spacers, ?C6H4(C≡CC6H4)n? (n = 1?5), a linear increase of the IL π?π* transition energy with the reciprocal of the intermetallic distance is theoretically predicted [?max = 1.99 ? 104 + 2.15 ? 105 (1/r) (S = 0) or ? = 2.01 ? 104 + 2.18 ? 105 (1/r) (S = 1)], which clearly indicates that the effective π-conjugation length increases with the number of phenylethyne repeating units. This is accompanied by an exponential decay of the antiferromagnetic coupling with the intermetallic distance [?J = 1.08 ? 103 exp(?0.31r)], which supports the ability of the extended π-conjugated OPEs to mediate the exchange interaction between the unpaired electrons of the two CuII centers with intermetallic distances in the range of 1.5?4.3 nm. Further developments may be then envisaged for this new family of oxamato-based dicopper(II) oligo-p-phenylethynophanes on the basis of the unique ligand capacity to act as a molecular antiferromagnetic wire.
    Mots-clés : ERMMES, POLE 2.


  • M. Castellano, R. Ruiz-García, J. Cano, M. Julve, F. Lloret, Y. Journaux, G. De Munno, et D. Armentano, « Multielectron transfer in a dicopper(ii) anthraquinophane », Chemical Communications, vol. 49, nᵒ 34, p. 3534.


  • N. Dia, L. Lisnard, Y. Prado, A. Gloter, O. Stéphan, F. Brisset, H. Hafez, Z. Saad, C. Mathonière, L. Catala, et T. Mallah, « Synergy in Photomagnetic/Ferromagnetic Sub-50 nm Core-Multishell Nanoparticles », Inorganic Chemistry, vol. 52, nᵒ 18, p. 10264-10274.
    Résumé : Based on nickel hexacyanidochromate and cobalt hexacyanidoferrate Prussian blue analogues, two series of photomagnetic/ferromagnetic sub-50 nm core multishell coordination nanoparticles have been synthesized in a surfactant-free one-pot multistep procedure with good control over the dispersity (10% standard deviation) and good agreement with the targeted size at each step. The composition and the valence state of each shell have been probed by different techniques that have revealed the predominance of CoII-NC-FeIII pairs in a series synthesized without alkali while CoIII-NC-FeII photoswitchable pairs have been successfully obtained in the photoactive coordination nanoparticles by control of Cs+ insertion. When compared, the photoinduced behavior of the latter compound is in good agreement with that of the model one. Exchange coupling favors a uniform reversal of the magnetization of the heterostructured nanoparticles, with a large magnetization brought by a soft ferromagnetic shell and a large coercivity due to a harder photomagnetic shell. Moreover, a persistent increase of the photoinduced magnetization is observed for the first time up to the ordering temperature (60 K) of the ferromagnetic component because of a unique synergy.
    Mots-clés : ERMMES, MMMAX, POLE 2.


  • R. Djeda, C. Desmarets, L. - M. Chamoreau, Y. Li, Y. Journaux, G. Gontard, et H. Amouri, « Meso-Helicates with Rigid Angular Tetradentate Ligand: Design, Molecular Structures, and Progress Towards Self-Assembly of Metal–Organic Nanotubes », Inorganic Chemistry, vol. 52, nᵒ 22, p. 13042-13047.

  • J. Ferrando-Soria, M. Castellano, R. Ruiz-Garcia, J. Cano, M. Julve, F. Lloret, C. Ruiz-Perez, J. Pasan, L. Canadillas-Delgado, D. Armentano, Y. Journaux, et E. Pardo, « Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl-Substituted para-Phenylene Spacers », Chemistry-a European Journal, vol. 19, nᵒ 36, p. 12124-12137.
    Résumé : Double-stranded anionic dinuclear copper(II) metallacyclic complexes of the paracyclophane type [Cu2L2](4-) have been prepared by the Cu-II-mediated self-assembly of different para-phenylenebis(oxamato) bridging ligands with either zero-, one-, or four-electron-donating methyl substituents (L=N,N-para-phenylenebis(oxamate) (ppba; 1), 2-methyl- N,N-para-phenylenebis(oxamate) (Meppba; 2), and 2,3,5,6-tetramethyl- N,N-para-phenylenebis(oxamate) (Me(4)ppba; 3)). These complexes have been isolated as their tetra-n-butylammonium (1a-3a), lithium(I) (1b-3b), and tetraphenylphosphonium salts (1c-3c). The X-ray crystal structures of 1a and 3c show a parallel-displaced -stacked conformation with a smaller deviation from perpendicularity between the two benzene rings and the basal planes of the square planar Cu-II ions when increasing the number of methyl substituents (average dihedral angles (phi) of 58.72(7) and 73.67(5)degrees for 1a and 3c, respectively). Variable-temperature (2.0-300K) magnetic-susceptibility measurements show an overall increase of the intramolecular antiferromagnetic coupling with the number of methyl substituents onto the para-phenylene spacers (-J=75-95, 100-124, and 128-144cm(-1) for 1a-c, 2a-c, and 3a-c, respectively; H=-JS(1)xS(2)). Cyclic voltammetry (CV) measurements show a reversible one-electron oxidation of the double polymethyl-substituted para-phenylenediamidate bridging skeleton at a relatively low formal potential that decreases with the number of methyl substituents (E-1=+0.33, +0.24, and +0.15V vs. SCE for 1-3, respectively). The monooxidized dicopper(II) -radical cation species 3 prepared by the chemical oxidation of 3 with bromine exhibits intense metal-to-ligand charge-transfer (MLCT) transitions in the visible and near-IR ((max)=595 and 875nm, respectively) regions together with a rhombic EPR signal with a seven-line splitting pattern due to hyperfine coupling with the nuclear spin of the two Cu-II ions. Density functional (DF) calculations for 3 evidence a characteristic iminoquinonoid-type short-long-short alternating sequence of CN and CC bonds for both tetramethyl-para-phenylenediamidate bridges and a large amount of spin density of negative sign mainly delocalized along each of the four benzene C atoms directly attached to the amidate N atoms, which is in agreement with a fully delocalized -stacked monoradical ligand description. Hence, the spins of the two Cu-II ions (S-Cu=1/2) that are antiparallel aligned in 3 (OFF state) become parallel in 3 (ON state). Further developments may be then envisaged for this new permethylated dicopper(II) paracyclophane with a redox noninnocent ligand as a prototype for molecular magnetic electroswitch.
    Mots-clés : bridging ligands, Copper, copper(ii) metallacyclophane, density functional calculations, electron-transfer, ERMMES, exchange coupling-constants, gaussian-basis sets, Magnetic properties, magnetic-properties, metallacycles, mixed-valence chemistry, MMMAX, organic electronics, POLE 2, polynuclear complexes, redox properties, spin-polarization, transition-metal-complexes.


  • M. Gruselle, Y. Li, N. Ovanesyan, V. Makhaev, G. Shilov, F. Mushenok, C. Trai

    n, et S. Aldoshin, « (S)-(−)-(2-MeBu)N(Pr)2MeI Salt as Template in the Enantioselective Synthesis of the Enantiopure Two-dimensional (S)-(−)-(2-MeBu)N(Pr)2Me[ΛMnΔCr(C2O4)3] Ferromagnet », Chirality, vol. 25, nᵒ 8, p. 444–448.
    Résumé : We describe herein the synthesis of (rac)- or enantiopure (S)-(−)-(2-MeBu)N(Pr)2MeI ammonium salts. These racemic and enantiopure ammonium salts were used as cationic templates to obtain new two-dimensional (2D) ferromagnets [(rac)-(2-MeBu)N(Pr)2Me][MnCr(C2O4)3] and [(S)-(−)-(2-MeBu)N(Pr)2Me][ΔMnΛ nCr(C2O4)3]. The absolute configuration of the hexacoordinated Cr(III) metallic ion in the enantiopure 2D network was determined by a circular dichroism measurement. The structure of [(2-MeBu)N(Pr)2Me][MnCr(C2O4)3], established by single crystal X-ray diffraction, belongs to the chiral P63 space group. According to direct current (dc) magnetic measurements, these compounds are ferrromagnets with a temperature Tc = 6°K. Chirality 25:444–448, 2013. © 2013 Wiley Periodicals, Inc.
    Mots-clés : 2D chiral networks, ammonium salts, ARC, ERMMES, ferromagnets, MMMAX, POLE 1, POLE 2.

  • A. Mondal, L. - M. Chamoreau, Y. Li, Y. Journaux, M. Seuleiman, et R. Lescouezec, « WCo Discrete Complex Exhibiting Photo- and Thermo-Induced Magnetisation », Chemistry-a European Journal, vol. 19, nᵒ 24, p. 7682-7685.
    Mots-clés : chain, co, cobalt, crystal-structure, cyanide, cyanide ligand, electron-transfer, ERMMES, high curie-temperature, large coercive field, metal-to-metal charge transfer, MMMAX, molecular switch, photoinduced magnetization, photomagnetism, POLE 2, prussian blue, single-molecule magnetism, Tungsten.

  • A. Mondal, P. - I. Dassie, L. - M. Chamoreau, Y. Journaux, M. Julve, L. Lisnard, et R. Lescouezec, « Combining Cyanometalates and Coordination Clusters: An Alternative Synthetic Route toward Original Molecular Materials », Crystal Growth & Design, vol. 13, nᵒ 10, p. 4190-4194.
    Résumé : As an original synthetic route to molecular magnetic materials, we have reacted partially blocked cyanometalates with preformed coordination cluster. The association of the fac-[Fe(Tp)(CN)(3)](-) assembling metalloligand with the [Cu-3(OH)(pz)(3)](2+) trigonal cluster has afforded a novel coordination network where the trimetallic copper(II) nodes are linked by the iron(III) complexes into chains and by coordinating acetate into a two-dimensional framework.
    Mots-clés : anisotropy, chain, complexes, crystal-structures, cyanide, ERMMES, magnetic-properties, MMMAX, networks, new-generation, POLE 2, polymers, secondary building units.


  • A. Mondal, S. Durdevic, L. - M. Chamoreau, Y. Journaux, M. Julve, L. Lisnard, et R. Lescouëzec, « A cyanide and hydroxo-bridged nanocage: a new generation of coordination clusters », Chemical Communications, vol. 49, nᵒ 12, p. 1181-1183.
    Résumé : Combining serendipitously-formed hydroxo-clusters, [CoII3(OH)(piv)4(L)]+ (where L = MeCN or Hpiv), with assembling cyanide building block, [FeIII(Tp)(CN)3]−, has led to an unprecedented architecture where polymetallic cobalt clusters and blocked tris-cyanide iron complexes define the apexes of a unique magne
    Mots-clés : ERMMES, MMMAX, POLE 2.


  • A. Mondal, Y. Li, M. Seuleiman, M. Julve, L. Toupet, M. Buron-Le Cointe, et R. Lescouëzec, « On/Off Photoswitching in a Cyanide-Bridged {Fe2Co2} Magnetic Molecular Square », Journal of the American Chemical Society, vol. 135, nᵒ 5, p. 1653-1656.
    Résumé : A repeatable bidirectional paramagnetic ? diamagnetic photomagnetic effect has been observed in the cyanide-bridged Fe?Co square complex {[Fe{B(pz)4}(CN)3]2[Co(bik)2]2}(ClO4)2·3H2O [B(pz)4 = tetrapyrazolylborate, bik = bis(1-methylimidazol-2-yl)ketone]. Magnetic measurements and low-temperature single-crystal X-ray diffraction experiments have shown that a complete electron transfer from the diamagnetic FeII ?Co III state to the paramagnetic FeIII ?Co II metastable state is induced by 808 nm laser light irradiation, whereas the diamagnetic state is recovered in an almost quantitative yield under irradiation at 532 nm.
    Mots-clés : ERMMES, MMMAX, POLE 2.

  • N. Pavlicek, C. Herranz-Lancho, B. Fleury, M. Neu, J. Niedenfuehr, M. Ruben, et J. Repp, « High-resolution scanning tunneling and atomic force microscopy of stereochemically resolved dibenzo[a,h]thianthrene molecules », Physica Status Solidi B-Basic Solid State Physics, vol. 250, nᵒ 11, p. 2424-2430.
    Résumé : Recently, we reported on the bistable configurational switching of dibenzo[a,h]thianthrene (DBTH) molecules adsorbed on NaCl using combined low-temperature scanning tunneling and atomic force microscopy (STM/AFM). Here, we discuss the intra-molecular contrast in AFM images of the molecules as a function of the tip-molecule distance. Our experiments show that ridges in the frequency shift do not necessarily correlate with chemical bonds in this case of a non-planar molecule. To explain this finding we compare images acquired at different tip-molecule distances to the calculated electron density of the molecules obtained from density functional theory calculations (DFT). In addition, we analyze the probability of finding different configurations after adsorption onto the surface. DBTH molecules in two configurations probed by a CO-functionalized tip. Insets show AFM (left) and STM (right) images of a U molecule.
    Mots-clés : ERMMES, MMMAX, POLE 2.

  • Y. Prado, M. - A. Arrio, F. Volatron, E. Otero, C. C. D. Moulin, P. Sainctavit, L. Catala, et T. Mallah, « Magnetic Anisotropy of Cyanide-Bridged Core and CoreShell Coordination Nanoparticles Probed by X-ray Magnetic Circular Dichroism », Chemistry-a European Journal, vol. 19, nᵒ 21, p. 6685-6694.
    Résumé : The local symmetry and local magnetic properties of 6nm-sized, bimetallic, cyanide-bridged CsNiCr(CN)6 coordination nanoparticles 1 and 8nm-sized, trimetallic, CsNiCr(CN)6@CsCoCr(CN)6 coreshell nanoparticles 2 were studied by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). The measurements were performed at the NiII, CoII, and CrIII L2,3 edges. This study revealed the presence of distorted NiII sites located on the particle surface of 1 that account for the uniaxial magnetic anisotropy observed by SQUID measurements. For the coreshell particles, a combination of the exchange anisotropy between the core and the shell and the pronounced anisotropy of the CoII ions is the origin of the large increase in coercive field from 120 to 890Oe on going from 1 to 2. In addition, XMCD allows the relative orientation of the magnetic moments throughout the coreshell particles to be determined. While for the bimetallic particles of 1, alignment of the magnetic moments of CrIII ions with those of NiII ions leads to uniform magnetization, in the coreshell particles 2 the magnetic moments of the isotropic CrIII follow those of CoII ions in the shell and those of NiII ions in the core, and this leads to nonuniform magnetization in the whole nanoobject, mainly due to the large difference in local anisotropy between the CoII ions belonging to the surface and the NiII ions in the core.
    Mots-clés : absorption, behavior, coordination networks, coreshell structures, ERMMES, exchange bias, gamma-fe2o3 nanoparticles, local-structure, magnetic anisotropy, mas nmr-spectroscopy, microemulsions, MMMAX, nanoparticles, POLE 2, polymers, prussian blue analogs, spin-density, transition metals.
  • A. Rajab, M. Touma, H. Rudler, C. Afonso, et M. Seuleiman, « Slow, spontaneous degradation of lansoprazole, omeprazole and pantoprazole tablets: isolation and structural characterization of the toxic antioxidants 3H-benzimidazole-2-thiones. », Die Pharmazie, vol. 68, nᵒ 9.
    Résumé : The spontaneous degradation of lansoprazole, omeprazole and pantoprazole tablets upon long-term and forced storage conditions was determined by high performance liquid chromatography (HPLC). The more abundant products could be isolated by liquid chromatography and their molecular weights determined by Mass Spectrometry (MS). Their structures, established according to their spectroscopic data, were compared to those of either the literature or of authentic samples. Thus lansoprazole led mainly to a mixture of 3H-benzimidazole-2-thione (2a) and 3H-benzimidazole-2-one (2c), omeprazole mainly to a mixture of 5-methoxy-3H-benzimidazole-2-thione (1a) and 2-hydroxymethyl-3, 5-dimethyl-4-methoxypyridine (1b), and pantoprazole, to 5-difluoromethoxy-3H-benzimidazole-2-thione (3a) and 2-hydroxymethyl-3, 4-dimethoxypyridine (3b). Although some of the degradation products had already been observed under different conditions, the detection of benzimidazole-2-thiones is unprecedented and their involvement as possible physiological, yet toxic antioxidants must be emphasized. Plausible, unified mechanisms for the formation of the different degradation products observed herein and in previous papers from the literature are suggested.
    Mots-clés : ERMMES, MMMAX, POLE 2.

  • J. Shao, Q. Ge, Y. Ouyang, C. - Z. Xie, X. - T. Zhang, J. - Y. Xu, et Y. Journaux, « Scalene-tricopper(II) bridged by 5-(1H-benzo[d]imidazol-2-yl-1H-imidazole-4-carboxylic acid: Synthesis, crystal structure and magnetic properties », Inorganic Chemistry Communications, vol. 36, p. 224-226.
    Résumé : New scalene tricopper complex [Cu-3(II)(HImbm)(bipy)6](ClO4)(4) center dot 3CH(3)OH center dot 4H(2)O (1) (H(3)Imbm = 5-(1H-benzo[d]imidazol-2-y1)-1H-imidazole-4-carboxylic acid, bipy = 2,2'-bipyridine) was synthesized. X-ray analysis reveals that 1 crystallizes in monoclinic P2(1)/c. Complex 1 can be described as three terminal [Cu(bpy)(2)](2+) units bridged by one asymmetric H(3)Imbm ligand with its peripheral three chelating pockets to capture three Cu atoms in a scalene-triangular geometry. The variable-temperature magnetic measurement was recorded for the crystallographically characterized 1, and the magnetic response was analyzed very well using a scalene triangle Cu3 model, indicating a dominant antiferromagnetic coupling with J(12) = 44.3 cm(-1), J(23) = -27.3 cm(-1), and g = 2.08, given J(13) = 0. (C) 2013 Elsevier B.V. All rights reserved.
    Mots-clés : ERMMES, MMMAX, POLE 2.

2012

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