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  • 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, sept. 2013.
    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, 2013.

  • 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, sept. 2013.
    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, Magnetic properties, Metallacycles, MMMAX, POLE 2.

  • M. Gruselle, Y. Li, N. Ovanesyan, V. Makhaev, G. Shilov, F. Mushenok, C. Train, 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, 2013.
    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, juin 2013.
    Mots-clés : chain, co, cobalt, crystal-structure, cyanide, cyanide ligand, electron-transfer, ERMMES, MMMAX, Photomagnetism, POLE 2, Tungsten.

  • A. Mondal, P. - I. Dassie, L. - M. Chamoreau, Y. Journaux, M. Julve, L. Lisnard, et R. Lescouëzec, « Combining Cyanometalates and Coordination Clusters: An Alternative Synthetic Route toward Original Molecular Materials », Crystal Growth & Design, vol. 13, nᵒ 10, p. 4190-4194, oct. 2013.
    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, 2013.

  • A. Mondal, Y. Li, M. Seuleiman, M. Julve, L. Toupet, M. Buron-Le Cointe, et R. Lescouëzec, « On/Off Photoswitching in a Cyanide-Bridged {Fe <sub>2</sub> Co <sub>2</sub> } Magnetic Molecular Square », Journal of the American Chemical Society, vol. 135, nᵒ 5, p. 1653-1656, févr. 2013.

  • 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, mai 2013.
    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, MMMAX, POLE 2.
  • 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, sept. 2013.
    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, oct. 2013.
    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.


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