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  • A. Benchohra, Y. Li, L. - M. Chamoreau, B. Baptiste, E. Elkaïm, N. Guillou, D. Kreher, et R. Lescouëzec, « The Atypical Hysteresis of [Fe(C6F5Tp)2]: Overlay of Spin-Crossovers and Symmetry-Breaking Phase Transition », Angewandte Chemie, vol. 133, nᵒ 16, p. 8885-8889, 2021.
    Résumé : The [FeII(C6F5Tp)2] spin-crossover complex is an atypical molecular switch, which can be converted upon annealing between two archetypal spin-crossover behaviours: from an extremely gradual spin-crossover to a broad hysteretic spin-transition (of ca. 65 K). The hysteresis shows an uncommon “rounded shape” that is reproducible upon cycling temperature. In depth structural studies reveal a first crystal phase transition, which occurs upon melting and recrystallizing at high temperature. This first irreversible transition is associated with a radical change in the crystal packing. More importantly, the “rounded and broad” hysteretic transition is shown to occur in a non-cooperative SCO system and is associated with the occurrence of a symmetry-breaking phase transition that appears when roughly ca. 50 % of the SCO complexes are switched.
    Mots-clés : ERMMES, POLE 2.

  • A. Harbi, Y. L. Godec, Y. Li, H. Moutaabbid, S. Benmokhtar, et M. Moutaabbid, « Experimental and theoretical investigation of the electronic, magnetic, and optical properties of a new oxyphosphate, Ni0.25Mn0.25TiO(PO4) », Journal of Physics and Chemistry of Solids, vol. 148, p. 109633, 2021.
    Résumé : The structural, magnetic, and optical properties of a new oxyphosphate, Ni0.25Mn0.25TiOPO4, have been investigated by X-ray diffraction (XRD) analysis, magnetic FC-ZFC measurements, and vibrational spectroscopy (Raman, IR, WDS, and UV/visible). XRD analysis showed that the compound crystallizes in a monoclinic structure, space group P21/c, with unit cell parameters of a = 7.3758(2) Å, b = 7.3255(2) Å, c = 7.3448(2) Å, and β = 120.25(2)°. Elemental analysis of the powder confirmed the presence of Ni, Mn, Ti, and P therein. Raman and IR spectra show strong bands at 749 and 787 cm−1, respectively, attributable to the vibration of –Ti–O–Ti–O– bonds in infinite chains. Magnetic studies have been performed in the temperature range from 2 to 300 K. The results revealed a weak antiferromagnetic coupling between spins in Ni0.25Mn0.25TiOPO4. The band-gap energy was estimated as Eg = 1.99 eV based on UV/Vis spectrophotometry. To better understand the experimental data, density functional theory (DFT) computations were performed within the generalized gradient approximation (GGA) and GGA + U. The partial density of states (PDOS) shows strong hybridization between O 2p, Mn 3d, and Ni 3d in the valence band and between Mn 3d, Ni 3d, and Ti 3d in the conduction band.
    Mots-clés : ERMMES, POLE 2.

  • J. - R. Jiménez, B. Xu, H. E. Said, Y. Li, J. von Bardeleben, L. - M. Chamoreau, R. Lescouëzec, S. Shova, D. Visinescu, M. - G. Alexandru, J. Cano, et M. Julve, « Field-induced single ion magnet behaviour of discrete and one-dimensional complexes containing [bis(1-methylimidazol-2-yl)ketone]-cobalt(II) building units », Dalton Transactions, vol. 50, nᵒ 44, p. 16353-16363, nov. 2021.
    Résumé : We describe herein the first examples of six-coordinate CoII single-ion magnets (SIMs) based on the β-diimine Mebik ligand [Mebik = bis(1-methylimidazol-2-yl)ketone]: two mononuclear [CoII(Rbik)2L2] complexes and one mixed-valence {CoIII2CoII}n chain of formulas [CoII(Mebik)(H2O)(dmso)(μ-NC)2CoIII2(μ-2,5-dpp)(CN)6]n·1.4nH2O (3) [L = NCS (1), NCSe (2) and 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine (3)]. Two bidentate Mebik molecules plus two monodentate N-coordinated pseudohalide groups in cis positions build somewhat distorted octahedral surroundings around the high-spin cobalt(II) ions in 1 and 2. The diamagnetic [CoIII2(μ-2,5-dpp)(CN)8]2− metalloligand coordinates the paramagnetic [CoII(Mebik)(H2O)(dmso)]2+ complex cations in a bis-monodentate fashion to afford neutral zigzag heterobimetallic chains in 3. Ab initio calculations, and cryomagnetic dc (2.0–300 K) and ac (2.0–12 K) measurements as well as EPR spectroscopy for 1–3 show the existence of magnetically isolated high-spin cobalt(II) ions with D values of 59.84–89.90 (1), 66.32–93.90 (2) and 70.40–127.20 cm−1 (3) and field-induced slow relaxation of the magnetization, being thus new examples of SIMs with transversal magnetic anisotropy. The analysis of their relaxation dynamics reveals that the relaxation of the magnetization occurs by the Raman (with values of the n parameter covering the range 6.0–6.8) and direct spin-phonon processes.
    Mots-clés : ERMMES, POLE 2.

  • A. Li, L. - M. Chamoreau, B. Baptiste, Y. Li, Y. Journaux, et L. Lisnard, « Solvothermal synthesis, structure and magnetic properties of heterometallic coordination polymers based on a phenolato-oxamato co-bidentate-tridentate ligand », Dalton Transactions, vol. 50, nᵒ 2, p. 681-688, janv. 2021.
    Résumé : The use of solvothermal conditions has succesfully led to the preparation of heterometallic 1D coordination polymers from a co-bidentate-tridentate phenolato-oxamato ligand. The reaction of the N-(2-hydoxyphenyl)oxamic acid (ohpma) with acetate salts of transition metal ions at 80 °C has yielded the heterobimetallic [Cu(ohpma)M(OAc)(DMF)2] (M = Co (1); Mn (2)) and the heterotrimetallic [Cu(ohpma)Co0.57Mn0.43(OAc)(DMF)2] (3) chain compounds. Single-crystal and powder diffraction studies show that the polymers are isostructural. Magnetic studies suggest the existence of an inter-chain two-dimensional antiferromagnetic interaction taking place in compounds 1–3.
    Mots-clés : ERMMES, POLE 2.

  • A. Li, J. Forté, Y. Li, Y. Journaux, et L. Lisnard, « Synthesis, structure and magnetic properties of an oxamate-based 1D coordination polymer built on pentametallic links », Inorganica Chimica Acta, vol. 521, p. 120320, juin 2021.
    Résumé : The solvothermal reaction of the hexadentate 2-(oxamato)benzoic acid ligand (oaba) with copper(II) and cobalt(II) ions has yielded the [Cu4Co3(oaba)4(OH)2(DMF)6]·2(DMF)·1H2O (1) 1D coordination polymer. The single-crystal X-ray diffraction study reveals the formation of a neutral chain built from pentametallic complexes where each multi-polydentate ligand bridges four metal centres. The atypical morphology observed here for an oxamate-based 1D polymer arises from the use of a ligand bearing extra coordination sites. Magnetometry indicates strong dominating antiferromagnetic interactions within the polymer resulting in a non-zero ferrimagnetic state at low temperature.
    Mots-clés : ERMMES, POLE 2.

  • P. P. Mudoi, A. Choudhury, Y. Li, R. Lescouëzec, R. Marimuthu, et N. Gogoi, « Observation of Protonation-Induced Spin State Switching in a Cyanido-Bridged {Fe2Co2} Molecular Square », Inorganic Chemistry, vol. 60, nᵒ 23, p. 17705-17714, déc. 2021.
    Résumé : The self-assembly of [Co(MeTPyA)(CH3COO)]PF6 (1) and [Fe(bbp)(CN)3]2– affords a cyanido-bridged square-shaped {Fe2Co2} tetranuclear complex, [{Co(MeTPyA)(μ2-NC)2Fe(bbp)(CN)}2]·3H2O (2; MeTPyA = tris((3,5-dimethylpyrazol-1-yl)methyl)amine and H2bbp = bis(2-benzimidazolyl)pyridine). The possibility of inducing an intramolecular electron transfer coupled spin transition in 2 by employing protonation as an external stimulant is explored. UV–visible spectrophotometric measurements, electrochemical and 1H NMR studies establish that a reversible intramolecular electron transfer coupled spin transition can be triggered in 2 upon addition of either acid or base.
    Mots-clés : ERMMES, POLE 2.

  • Q. P. Xuan, J. Glatz, A. Benchohra, J. - R. Jiménez, R. Plamont, L. - M. Chamoreau, A. Flambard, Y. Li, L. Lisnard, D. Dambournet, O. J. Borkiewicz, M. - L. Boillot, L. Catala, A. Tissot, et R. Lescouëzec, « Building responsive materials by assembling {Fe4Co4} switchable molecular cubes », Journal of Materials Chemistry C, vol. 9, nᵒ 28, p. 8882-8890, juill. 2021.
    Résumé : Responsive materials that can answer to chemical or physical external stimuli offer numerous prospects in material science. Here, we have elaborated a two-step synthetic approach that allows incorporating molecular cubic switches into a polymeric material. Firstly, a preformed half-capped, Cs+-templated {Fe4Co4} cyanido-polymetallic cubic unit (“pro-cube”) is obtained and proven to be stable in solution, as demonstrated by paramagnetic NMR. Secondly, the reaction of the pro-cube with a ditopic scorpionate ligand enables the precipitation of a polymeric network containing the cubic unit. Furthermore, the adequately chosen ditopic ligand that coordinates the Co ions of the pro-cube allows us to preserve the switchable properties of the cubic unit. Indeed, the magnetic properties of the polymeric material compare well with those of the molecular cubic model that is obtained by reacting a non-bridging scorpionate ligand, and that was prepared as a reference. Both the polymeric material and the molecular model cube show a thermally-induced metal–metal electron transfer near room temperature. Interestingly, the magnetic state of the polymeric material is shown to depend on its hydration state, indicating its capability to act as a chemo-sensor.
    Mots-clés : ERMMES, POLE 2.

  • L. Zhang, M. - A. Arrio, S. Mazerat, L. Catala, W. Li, E. Otero, P. Ohresser, L. Lisnard, C. Cartier dit Moulin, T. Mallah, et P. Sainctavit, « Magnetic Hysteresis in a Monolayer of Oriented 6 nm CsNiCr Prussian Blue Analogue Nanocrystals », Inorganic Chemistry, vol. 60, nᵒ 21, p. 16388-16396, nov. 2021.
    Résumé : Prussian blue analogue nanocrystals of the CsINiII[CrIII(CN)6] cubic network with 6 nm size were assembled as a single monolayer on highly organized pyrolytic graphite (HOPG). X-ray magnetic circular dichroism (XMCD) studies, at the Ni and Cr L2,3 edges, reveal the presence of an easy plane of magnetization evidenced by an opening of the magnetic hysteresis loop (coercive field of ≈200 Oe) when the magnetic field, B, is at 60° relative to the normal to the substrate. The angular dependence of the X-ray natural linear dichroism (XNLD) reveals both an orientation of the nanocrystals on the substrate and an anisotropy of the electronic cloud of the NiII and CrIII coordination sphere species belonging to the nanocrystals’ surface. Ligand field multiplet (LFM) calculations that reproduce the experimental data are consistent with an elongated tetragonal distortion of surface NiII coordination sphere responsible for the magnetic behavior of monolayer.
    Mots-clés : ERMMES, POLE 2.


  • A. Benchohra, C. Méthivier, J. Landoulsi, D. Kreher, et R. Lescouëzec, « Electrospray ionization: an efficient approach to deposit polymetallic molecular switches onto gold surfaces », Chemical Communications, vol. 56, nᵒ 48, p. 6587-6589, 2020.
    Résumé : Electrospray ionization (EI) deposition is proven efficient in obtaining monolayers of a polymetallic charge transfer complex on gold surfaces. , Electrospray ionization (EI) deposition is proven efficient in obtaining monolayers of a polymetallic charge transfer complex on gold surfaces. The molecule's integrity is monitored by using PM-IRRAS and XPS. This approach broadens the perspective of molecular magnetic switch deposition, which is currently dominated by the thermal evaporation of monometallic spin crossover (SCO) complexes.
    Mots-clés : ERMMES, POLE 2.

  • J. Glatz, L. - M. Chamoreau, A. Flambard, J. - F. Meunier, A. Bousseksou, et R. Lescouëzec, « Thermo- and electro-switchable Cs⊂{Fe <sub>4</sub> –Fe <sub>4</sub> } cubic cage: spin-transition and electrochromism », Chemical Communications, vol. 56, nᵒ 74, p. 10950-10953, 2020.
    Résumé : The Cs⊂{Fe 4 –Fe 4 } cube is a dual redox and magnetic switch showing remarkable electrochromic properties and spin-transition in its neutral state. , A mixed valence Cs⊂{Fe 4 –Fe 4 } cyanido-cube was synthesized and structurally characterized. The molecule, which is robust in solution, shows remarkable electronic versatility. Electrochromic properties associated with nine different electronic states are observed in solution together with a thermo-induced spin-transition in the solid state.
    Mots-clés : ERMMES, POLE 2.

  • J. ‐R. Jiménez, J. Glatz, A. Benchohra, G. Gontard, L. ‐M. Chamoreau, J. ‐F. Meunier, A. Bousseksou, et R. Lescouëzec, « Electron Transfer in the Cs⊂{Mn <sub>4</sub> Fe <sub>4</sub> } Cubic Switch: A Soluble Molecular Model of the MnFe Prussian‐Blue Analogues », Angewandte Chemie International Edition, vol. 59, nᵒ 21, p. 8089-8093, mai 2020.

  • S. Kamilya, S. Ghosh, Y. Li, P. Dechambenoit, M. Rouzières, R. Lescouëzec, S. Mehta, et A. Mondal, « Two-Step Thermoinduced Metal-to-Metal Electron Transfer and ON/OFF Photoswitching in a Molecular [Fe2Co2] Square Complex », Inorganic Chemistry, vol. 59, nᵒ 17, p. 11879-11888, nov. 2020.
    Mots-clés : ERMMES, POLE 2.
    Note Note
    <p>doi: 10.1021/acs.inorgchem.0c02053</p>

  • A. Li, Y. Li, L. - M. Chamoreau, C. Desmarets, L. Lisnard, et Y. Journaux, « A Bis-Polydentate Oxamate-Based Achiral Ligand That Can Stabilize a Macrocyclic Mixed Valence Compound or Induce a 1D Helical Chain », European Journal of Inorganic Chemistry, vol. 2020, nᵒ 34, p. 3311-3319, 2020.
    Résumé : The reaction of the N-(2-hydroxyphenyl)oxamate ligand (ohpma) has been investigated with cobalt(II) and copper(II) ions. It has led to two coordination compounds, (TMA)3[CoIII(ohpma)2CoII(MeOH)23]·10H2O·5MeOH (1) and (HNEt3)[Cu(ohpma)] (2). Both compounds have been characterized by single-crystal X-ray diffraction and magnetometry. The X-ray diffraction studies have revealed atypical structures that are not commonly observed in oxamate coordination chemistry with a macrocyclic arrangement for the mixed-valence cobalt-based complex 1, and a helical chiral chain for compound 2. In the latter, the bis-polydentate nature of the (ohpma)3– ligand with distinct tridentate and bidentate coordination sites creates a chirogenic center on the copper ion. The investigation of the magnetic properties shows for complex 1 a single-molecule magnet behavior detectable under static field, while antiferromagnetic interactions dominate the behavior of 2.
    Mots-clés : ARC, ERMMES, POLE 1, POLE 2.

  • Y. Li, A. Benchohra, B. Xu, B. Baptiste, K. Béneut, P. Parisiades, L. Delbes, A. Soyer, K. Boukheddaden, et R. Lescouëzec, « Pressure-Induced Conversion of a Paramagnetic FeCo Complex into a Molecular Magnetic Switch with Tuneable Hysteresis », Angewandte Chemie International Edition, vol. 59, nᵒ 39, p. 17272-17276, 2020.
    Résumé : A key challenge in the design of magnetic molecular switches is to obtain bistability at room temperature. Here, we show that application of moderate pressure makes it possible to convert a paramagnetic FeIII2CoII2 square complex into a molecular switch exhibiting a full dia- to paramagnetic transition: FeIICoIII ⇔ FeIIICoII. Moreover, the complex follows a rare behavior: the higher the pressure, the broader the magnetic hysteresis. Thus, the application of an adequate pressure allows inducing a magnetic bistability at room temperature with predictable hysteresis width. The structural studies at different pressures suggest that the pressure-enhanced bistability is due to the strengthening of intermolecular interactions upon pressure increase. An original microscopic Ising-like model including pressure effects is developed to simulate this unprecedented behavior. Overall, this study shows that FeCo complexes could be very sensitive piezo switches with potential use as sensors.
    Mots-clés : ERMMES, POLE 2.

  • Y. Shi, Y. Li, et T. Coradin, « Magnetically-oriented type I collagen-SiO2@Fe3O4 rods composite hydrogels tuning skin cell growth », Colloids and Surfaces B: Biointerfaces, vol. 185, p. 110597, 2020.


  • J. Besnardiere, B. Ma, A. Torres-Pardo, G. Wallez, H. Kabbour, J. M. González-Calbet, H. J. Von Bardeleben, B. Fleury, V. Buissette, C. Sanchez, T. Le Mercier, S. Cassaignon, et D. Portehault, « Structure and electrochromism of two-dimensional octahedral molecular sieve h’-WO3 », Nature Communications, vol. 10, nᵒ 1, p. 327, janv. 2019.
    Résumé : Octahedral molecular sieves (OMS) are built of transition metal-oxygen octahedra that delimit sub-nanoscale cavities. Compared to other microporous solids, OMS exhibit larger versatility in properties, provided by various redox states and magnetic behaviors of transition metals. Hence, OMS offer opportunities in electrochemical energy harnessing devices, including batteries, electrochemical capacitors and electrochromic systems, provided two conditions are met: fast exchange of ions in the micropores and stability upon exchange. Here we unveil a novel OMS hexagonal polymorph of tungsten oxide called h’-WO3, built of (WO6)6 tunnel cavities. h’-WO3 is prepared by a one-step soft chemistry aqueous route leading to the hydrogen bronze h’-H0.07WO3. Gentle heating results in h’-WO3 with framework retention. The material exhibits an unusual combination of 1-dimensional crystal structure and 2-dimensional nanostructure that enhances and fastens proton (de)insertion for stable electrochromic devices. This discovery paves the way to a new family of mixed valence functional materials with tunable behaviors.
    Mots-clés : ERMMES, POLE 2.

  • N. Daffé, J. - R. Jiménez, M. Studniarek, A. Benchohra, M. - A. Arrio, R. Lescouëzec, et J. Dreiser, « Direct Observation of Charge Transfer and Magnetism in Fe4Co4 Cyanide-Bridged Molecular Cubes », The Journal of Physical Chemistry Letters, vol. 10, nᵒ 8, p. 1799-1804, avr. 2019.
    Résumé : We have studied the zero-dimensional cubane molecular correspondent of a Prussian blue analogue Cs–Fe4Co4 at low temperature and high magnetic field by means of L-edge X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We probe the magnetic and electronic structures of Fe and Co separately upon light irradiation, which allows us to observe directly the electron transfer coupled to a spin transition phenomenon within the molecular cubes and to investigate the nature of the metastable photoexcited state. The magnetic moments in the photoexcited state are found to be M = 1.3μB (Mspin = 0.59μB with large orbital moment, Morbit = 0.74μB) for low-spin FeIII and M = 1.5μB (Mspin = 1.08μB with orbital moment, Morbit = 0.41μB) for high-spin CoII at 2 K and 6.8 T. From our results, we evidence that a strong antiferromagnetic coupling between the metal ions can be ruled out.
    Mots-clés : ERMMES, POLE 2.

  • S. De, A. Flambard, D. Garnier, P. Herson, F. H. Köhler, A. Mondal, K. Costuas, B. Gillon, R. Lescouëzec, B. Le Guennic, et F. Gendron, « Probing the Local Magnetic Structure of the [FeIII(Tp)(CN)3]− Building Block Via Solid-State NMR Spectroscopy, Polarized Neutron Diffraction, and First-Principle Calculations », Chemistry – A European Journal, vol. 25, nᵒ 52, p. 12120-12136, 2019.
    Résumé : Abstract The local magnetic structure in the [FeIII(Tp)(CN)3]− building block was investigated by combining paramagnetic Nuclear Magnetic Resonance (pNMR) spectroscopy and polarized neutron diffraction (PND) with first-principle calculations. The use of the pNMR and PND experimental techniques revealed the extension of spin-density from the metal to the ligands, as well as the different spin mechanisms that take place in the cyanido ligands: Spin-polarization on the carbon atoms and spin-delocalization on the nitrogen atoms. The results of our combined density functional theory (DFT) and multireference calculations were found in good agreement with the PND results and the experimental NMR chemical shifts. Moreover, the ab-initio calculations allowed us to connect the experimental spin-density map characterized by PND and the suggested distribution of the spin-density on the ligands observed by NMR spectroscopy. Interestingly, significant differences were observed between the pseudo-contact contributions of the chemical shifts obtained by theoretical calculations and the values derived from NMR spectroscopy using a simple point-dipole model. These discrepancies underline the limitation of the point-dipole model and the need for more elaborate approaches to break down the experimental pNMR chemical shifts into contact and pseudo-contact contributions.
    Mots-clés : ERMMES, POLE 2.

  • D. Garnier, A. Mondal, Y. Li, P. Herson, L. - M. Chamoreau, L. Toupet, M. Buron Le Cointe, E. M. B. Moos, F. Breher, et R. Lescouëzec, « Tetranuclear [FeII2FeIII2]2+ molecular switches: [FeII(bik)2(N–)2] spin-crossover complexes containing [FeIII(Tp)(CN)3]– metalloligands as N-donor », Comptes Rendus Chimie, mai 2019.
    Résumé : Three novel mixed valence cyanide-bridged {FeIII2FeII2} square complexes were obtained through the self-assembling of [FeIII(Tp)(CN)3]- or [FeIII(Tp*)(CN)3]− cyanido building blocks with the in situ formed [FeII(bik)2(S)2] complex (Tp = hydrotris (pyrazol-1-yl)borate, Tp* = hydrotris (3,5-dimethyl-pyrazol-1-yl)borate, bik = bis(1-methylimidazol-2-yl)ketone, S = solvent). The structures of these three complexes (2, 3 and 4) are reminiscent of that of our previously published square complex {[FeIII(Tp)(CN)3]2 [FeII(bik)2]2}·[FeIII(Tp)(CN)3]2·18H2O·4CH3OH (1). They consist of cyanide-bridged square dicationic complexes, ClO4− (2 and 3) or BF4− (4) counterions and solvate molecules. The FT-IR cyanide stretching vibrations observed at νCN ≈ 2145–60 cm−1 are typical of {FeIII–CN–FeII} moieties. The investigation of the magnetic properties of 2 reveals the occurrence of spin-crossover centered at T1/2 = 227 K. The χMT variation, ca. 7 cm3 mol−1 K, reflects the complete spin-state change occurring on both {FeII(bik)(–NC)2} moieties (–NC represents the cyanido building blocks). The Slichter–Drickamer model leads to a weak cooperativity factor, Γ = 1.6 kJ mol−1 (with Γ < 2RT1/2), which reflects the gradual spin-state change. This is in agreement with the molecular structure of 2, which does not present significant intermolecular interactions. The calculated enthalpy and entropy variations associated with the spin-state equilibrium are ΔH = 24 kJ mol−1 and ΔS = 105 J K−1 mol−1. In contrast, 3 and 4 show only partial spin-crossover in the accessible temperature range (2–400 K) as the T1/2 are shifted toward higher temperatures (ca. T1/2 > 400 K). Although no photomagnetic effect is observed for 3, compound 4 shows a moderate increase in the magnetization upon irradiation at low temperature. This phenomenon is ascribed to the light-induced excited spin-state trapping (LIESST) effect. Interestingly, the complex 2 also shows a remarkable LIESST effect, which is observed with different laser lights covering the visible and near-infrared range. The resulting χMT value obtained in the photoinduced state suggests the occurrence of a ferromagnetic interaction inside the {FeIII–CN–FeII} units. Résumé Trois nouveaux complexes carrés {FeIII2FeII2} à pont cyanure et à valence mixte ont été obtenus par auto-assemblage des précurseurs cyanurés [FeIII(Tp)(CN)3]− ou [FeIII(Tp*)(CN)3]− et du complexe cationique [FeII(bik)2(S)2] formé in situ (Tp = hydrotris (pyrazol-1-yl)borate, Tp* = hydrotris (3,5-dimethyl-pyrazol-1-yl)borate, bik = bis(1-methylimidazol-2-yl)cétone, S = solvant). Les structures de ces trois complexes (2, 3 et 4) sont similaires à celle du complexe {[FeIII(Tp)(CN)3]2[FeII(bik)2]2}[FeIII(Tp)(CN)3]2·18H2O·4CH3OH (1) préalablement publié. Elles sont constituées de complexes carrés dicationiques à pont cyanure, de contre-ions ClO4− (2 and 3) ou BF4− (4) et de molécules de solvant. Les vibrations d’élongation des cyanures, observée en spectroscopie IR à νCN ≈ 2145–60 cm−1, sont caractéristiques d'unités {FeIII–CN–FeII}. L’étude des propriétés magnétiques de 2 révèle un équilibre de spin centré à T1/2 = 227 K. La variation du produit χMT, ca. 7 cm3 mol−1 K, traduit une conversion de spin complète sur chacune des unités {FeII(bik)(–NC)2} du carré (–NC représente le complexe précurseur cyanuré). L'analyse des données par le modèle de Slichter–Drickamer conduit à un faible facteur de coopérativité, Γ = 1.6 kJ mol−1 K (with Γ < 2RT1/2), en accord avec un changement d’état de spin graduel. Ces données sont en accord avec la structure de 2 qui ne montre pas d'interactions intermoléculaires notables. Les valeurs des variations d'enthalpie et d'entropie associées à la conversion de spin sont ΔH = 24 kJ mol−1 et ΔS = 105 J K−1 mol−1. Au contraire de 2, les composés 3 and 4 présentent seulement une conversion de spin partielle dans le domaine de température exploré (2–400 K), avec des valeurs T1/2 déplacées vers les hautes températures (ca. T1/2 > 400 K). Tandis qu'on n'observe pas d'effet photomagnétique pour 3 et seulement un faible effet dans 4, le composé 2 présente une forte augmentation de son aimantation sous irradiation à basse température. Cet effet est dû au piégeage photo-induit d'un état excité de spin (effet « LIESST », Light-Induced Excited Spin-State Trapping). Il est observé avec différentes sources laser couvrant le spectre visible et le proche infrarouge. Les valeurs de χMT obtenues dans l’état photo-induit suggèrent la présence d'une interaction ferromagnétique au sein de la paire {FeIII–CN–FeII}.
    Mots-clés : ERMMES, POLE 2.

  • A. Harbi, H. Moutaabbid, Y. Li, C. Renero-Lecuna, M. Fialin, Y. Le Godec, S. Benmokhtar, et M. Moutaabbid, « The effect of cation disorder on magnetic properties of new double perovskites La2NixCo1-xMnO6 (x = 0.2–0.8) », Journal of Alloys and Compounds, vol. 778, p. 105-114, mars 2019.
    Résumé : Solid solutions of new double perovskite oxides La2NixCo1-xMnO6 (x = 0.2, 0.25, 0.5, 0.75, 0.8) were synthesized by solid-state reaction method. The X-ray powder diffraction data show that all the compounds crystallize in the monoclinic structure with space group P21/n at room temperature. The elementary composition of the powders was determined by the electron Probe Microanalysis. Raman and IR spectra show strong bands at (520, 650 cm−1) and (426, 600 cm−1) respectively, attributed to the stretching vibration of Ni/Co-O and Mn-O bonds in the structure. The magnetic studies for all the compounds have been performed in both DC and AC magnetic fields in the temperature range from 2 to 300 K. All samples exhibit a main paramagnetic to ferromagnetic (PM-FM) transition between 232 K and 260 K, and their Curie temperature increases rapidly with increasing x values. Three samples with x = 0.2, 0.25 and 0.5 respectively display also a secondary PM-FM transition between 200 K and 208 K. The thermal variation of out of phase component of AC susceptibility presents also frequency-dependent transitions between 65 K and 110 K unfolding the existence of super-paramagnetic mono-domains in all samples. The band gap energy has been calculated and revealing semiconductor behavior for all samples.
    Mots-clés : ERMMES, POLE 2.

  • M. Okubo, J. Long, D. R. Talham, et R. Lescouëzec, « Solid-state electrochemistry of metal cyanides », Comptes Rendus Chimie, vol. 22, nᵒ 6, p. 483 - 489, 2019.
    Résumé : Efficient energy storage in the form of batteries contribute

    s to building sustainable society. As advanced batteries need positive electrode materials capable of larger capacity, higher voltage, and lower cost, it is important to search for novel electrode materials. Among various inorganic/organic materials, cyanido-bridged coordination compounds are promising candidates for battery electrodes due to their ability to undergo solid-state redox reaction associated with ion (de)intercalation. In this review, recent results about the thermodynamic and kinetic aspects of the solid-state electrochemistry of cyanido-bridged coordination compounds are summarized, providing a fundamental basis toward developing cyanide electrodes for advanced batteries. Résumé Le stockage de l’énergie dans des batteries performantes est un élément clé pour le développement des énergies renouvelables et d'un modèle de société durable. Un des défis pour construire de nouvelles batteries plus performantes est le développement de matériaux d'intercalation pour cathode présentant de plus grandes capacités, de plus grands voltages et des coûts réduits. Parmi les divers matériaux organiques et inorganiques explorés, les polymères de coordination à pont cyanure sont des candidats prometteurs. Ceux ci peuvent s'oxyder et se réduire à l’état solide en (dés)intercalant des ions. Dans cette revue, quelques résultats récents sur les aspects thermodynamiques et cinétiques des propriétés électrochimiques des polymères de coordination à pont cyanure sont résumés, démontrant leur potentiel intérêt comme életcrodes dans de nouvelles batteries.
    Mots-clés : ERMMES, POLE 2.
    Note Note
    <p>Forty years of exchange interactions on the occasion of the 75th birthday of Michel Verdaguer</p>

  • W. X. C. Oliveira, W. D. do Pim, C. B. Pinheiro, Y. Journaux, M. Julve, et C. L. M. Pereira, « Monitoring the hydrogen bond net configuration and the dimensionality of aniline and phenyloxamate by adding 1H-pyrazole and isoxazole as substituents for molecular self-recognition », CrystEngComm, vol. 21, nᵒ 17, p. 2818-2833, avr. 2019.
    Résumé : This work describes the synthesis and characterization of a new class of oxamic acid derivatives containing pyrazole and isoxazole as substituents to investigate their ability to form hydrogen bonds aiming at applying them in crystal engineering and molecular self-recognition. In this respect, we report a new synthesis of 2-(4-nitrophenyl)-1,3-propanedial (1) in high yield using SOCl2 as a chlorinating agent. The new oxamic esters 4-(1H-pyrazol-4-yl)phenylene-N-(ethyloxamate) (2d) and 4-(1,2-oxazol-4-yl)phenylene-N-(ethyloxamate) (3d) were prepared from 1. The synthetic route consists of the cyclisation of 1 either with hydrazine to afford 4-(-aminophenyl)-1H-pyrazole (2a) or with hydroxylamine to obtain the isoxazole-based molecule 4-(4-nitrophenyl)-1,2-oxazole (3a). The reduction of 2a and 3a was carried out in an acidic/tin solution to yield 4-(4-ammoniophenyl)-1H-pyrazol-2-ium trichlorostannate(II) chloride monohydrate (2b) and 4-(4-ammoniophenyl)-1,2-oxazole hexachlorostannate(IV) (3b). Basic extraction of 3b provided 4-(4-aminophenyl)-1,2-oxazole (3c). The reduction of 2a to 4-(4-aminophenyl)-1H-pyrazole (2c) was achieved by means of hydrazine associated with supported palladium on carbon. The condensation of 2c and 3c with ethyl chlorooxoacetate delivers oxamic esters 2d and 3d. In n-tetrabutylammonium hydroxide solution 2d is fully hydrolyzed, obtaining the n-tetrabutylammonium salt of 4-(1H-pyrazole-4-yl)phenylene-N-oxamate as a hemihydrate (2e). The low stability of isoxazole molecules in basic solutions was proved by crystallizing the n-tetrabutylammonium salt of 1-cyano-1-(4-nitrophenyl)-2-oxoethanide (3f) (obtained by cleavage of 3d with n-Bu4NOH) and preparing its conjugated acid 2-(4-nitrophenyl-3-oxopropanenitrile (3e). The structures of 2b, 3b, 3d and 2e were solved by single crystal X-ray diffraction techniques. The analysis of their crystal packing reveals hydrogen bond features compatible for all compounds as well as some differences depending on the pH of the crystallization solution and the presence or absence of the oxamate group due to the increase of hydrogen bond donors and acceptors.
    Mots-clés : ERMMES, POLE 2.
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  • O. Stetsiuk, V. Synytsia, S. R. Petrusenko, V. N. Kokozay, A. El-Ghayoury, J. Cano, F. Lloret, M. Julve, B. Fleury, et N. Avarvari, « Co-existence of ferro- and antiferromagnetic interactions in a hexanuclear mixed-valence CoIII2MnII2MnIV2 cluster sustained by a multidentate Schiff base ligand », Dalton Transactions, vol. 48, nᵒ 31, p. 11862-11871, 2019.
    Résumé : The successful utilization of the “direct synthesis” approach yielded the unprecedented hexanuclear complex of formula [Co2MnII2MnIV2(L1)4Cl2(μ3-O)2(dmf)4]·2dmf (1) (H3L is the Schiff base derived from the condensation of salicylaldehyde and 3-aminopropane-1,2-diol). Single crystal X-ray analysis revealed that 1 crystallizes in the monoclinic system P21/c and it contains a rare mixed-valence CoIII2MnII2MnIV2(μ2-O)8(μ3-O)2 core where all metal ions are linked through the phenolato and alkoxo groups of the L3− ligand. Besides the charge balance resulting from the X-ray structure, the oxidation state of the metal ions has been confirmed by XPS spectroscopy. Cryomagnetic studies indicate the coexistence of ferro- (MnIV–MnII, J2 = +1.10(3) cm−1, J3 = +2.19(3) cm−1; MnII–MnII, j = +0.283(3) cm−1) and antiferromagnetic interactions (MnIV–MnIV, J1 = −17.31(4) cm−1), with the six-coordinate CoIII ions being diamagnetic. DFT type calculations were carried out to substantiate these values. The energy diagram for the different spin states using the best-fit parameters shows the occurrence of six low-lying spin states (S = 0–5) which are close in energy but clearly separated from the remaining ones, with the ground spin state being S = 5. Complex 1 is found to be the first example where weak ferromagnetic exchange between MnII ions through the long –O–MnIV–O– pathway takes place.
    Mots-clés : ERMMES, POLE 2.


  • T. F. C. Cruz, C. A. Figueira, J. C. Waerenborgh, L. C. J. Pereira, Y. Li, R. Lescouëzec, et P. T. Gomes, « Synthesis, characterization and magnetism of homoleptic bis(5-aryl-2-iminopyrrolyl) complexes of iron(II) and cobalt(II) », Polyhedron, vol. 152, p. 179-187, 2018.

  • S. De, L. - M. Chamoreau, H. El Said, Y. Li, A. Flambard, M. - L. Boillot, S. Tewary, G. Rajaraman, et R. Lescouëzec, « Thermally-Induced Spin Crossover and LIESST Effect in the Neutral [FeII(Mebik)2(NCX)2] Complexes: Variable-Temperature Structural, Magnetic, and Optical Studies (X = S, Se; Mebik = bis(1-methylimidazol-2-yl)ketone) », Frontiers in Chemistry, vol. 6, août 2018.

  • S. De, S. Tewary, D. Garnier, Y. Li, G. Gontard, L. Lisnard, A. Flambard, F. Breher, M. - L. Boillot, G. Rajaraman, et R. Lescouëzec, « Solution and Solid-State Study of the Spin-Crossover [FeII(R-bik)3](BF4)2 Complexes (R = Me, Et, Vinyl) », European Journal of Inorganic Chemistry, vol. 2018, nᵒ 3-4, p. 414-428, janv. 2018.
    Résumé : The magnetic properties of three spin-crossover complexes, [FeII(R-bik)3](BF4)2·nH2O (1–3), based on bis(imidazolyl)ketone ligands, were investigated in solution and the solid state. Their properties were compared with those of the ketone-free analogue, [FeII(bim)3](OTf)2 (4). The alkyl and vinyl R groups have weak influence on the transition temperature, T1/2, in solution, while stronger differences are observed in the solid state, because different intermolecular interactions occur in 1–3. The spin-state equilibria in solution were followed by SQUID magnetometry and the Evans NMR spectroscopy method. Interestingly, the equilibria can also be simply and efficiently probed by following the temperature dependence of an adequately chosen 1H chemical shift. Overall, these experiments give coherent results, with T1/2 located between 320 and 335 K, a narrow range, in comparison with the solid state. DFT calculations have allowed the rationalization of the magnetic differences. The molecular-orbital and spin-density calculations reveal that the presence of the C=O group between the imidazolyl units in the ligands of 1–3 leads to an extended aromatic system, an effective π-acceptor effect, stabilizing the LS state and reducing the LS–HS gap, in comparison with 4.
    Mots-clés : Density functional calculations, ERMMES, Iron, Paramagnetic NMR spectroscopy, POLE 2, Spin crossover.
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  • J. - R. Jiménez, A. Sugahara, M. Okubo, A. Yamada, L. - M. Chamoreau, L. Lisnard, et R. Lescouëzec, « A [FeIII(Tp)(CN)3]− scorpionate-based complex as a building block for designing ion storage hosts (Tp: hydrotrispyrazolylborate) », Chemical Communications, avr. 2018.
    Résumé : Using a scorpionate-based complex, [FeIII(Tp)(CN)3]−, as a building block, a new cyanide-based molecular material [{FeIII(Tp)(CN)3}2NiII(H2O)2]·4H2O (1), which can be viewed as a lower dimensional model of Prussian blue analogues, was investigated as a lithium-ion storage host.
    Mots-clés : ERMMES, POLE 2.
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  • Y. Journaux, J. Ferrando-Soria, E. Pardo, R. Ruiz-Garcia, M. Julve, F. Lloret, J. Cano, Y. Li, L. Lisnard, P. Yu, H. Stumpf, et C. L. M. Pereira, « Design of Magnetic Coordination Polymers Built from Polyoxalamide Ligands: A Thirty Year Story », European Journal of Inorganic Chemistry, vol. 2018, nᵒ 3-4, p. 228-247, janv. 2018.
    Résumé : The aim of this review is to pay tribute to the legacy of O. Kahn. Kahn's credo was to synthesize magnetic compounds with predictable structure and magnetic properties. This is illustrated herein with results obtained by Kahn's group during his Orsay period thirty years ago, but also on the basis of our recent results on the synthesis of coordination polymers with oxamate ligands. The first part of this review is devoted to a short description of the necessary knowledge in physics and theoretical chemistry that Kahn and his group have used to select oxamate ligands, the complex-as-ligand strategy and the synthesis of heterobimetallic systems. Then, we describe the strategies we have later used to obtain the desired target compounds. The use of complexes as building-blocks, associated to a control of the metal ions chirality and stoichiometry, allowed us to obtain coordination polymers with predictable dimensionality. For the synthesis of single-chain magnets (SCMs) we show that the ligand chemical flexibility makes the isolation of the chains in the solid and the occurence of slow magnetic relaxation possible. For 1D and 2D molecule-based magnets (MBMs), the magnetic ordering strongly depends on the interchain or interplane interactions, which are difficult to control. Again the flexibility of the oxamate ligands allowed their strengthening in the solid sate, yielding MBMs with critical temperatures up to 30 K. We will also present our results on 3D coordination polymers, particularly on the porous magnets displaying large octagonal channels. This family of porous MBMs possess outstanding chemical properties, such as post-synthetic transformation in the solid state. Finally, we will also show that oxamate ligands allows the design of multifunctional materials, as in the case of the first chiral SCM. Overall, the results presented in this review show the impressive potential the oxamate ligands have for the design of coordination polymers.
    Mots-clés : Bridging ligands, Coordination Polymer, ERMMES, Heterometallic complexes, Ligand design, Magnetic properties, Metal-Organic Frameworks, Metallacycles, N, O ligands, POLE 2.
    Pièce jointe Full Text PDF 8.5 Mo (source)

  • R. Plamont, J. Tami, J. - R. Jimenez, A. Benchohra, O. Khaled, G. Gontard, Y. Li, et R. Lescouëzec, « A soluble cyanide-bridged {Fe <sub>4</sub> Ni <sub>4</sub> } box encapsulating a Cs <sup>+</sup> ion: synthesis, structure and electronic properties », Journal of Coordination Chemistry, vol. 71, nᵒ 5, p. 601-614, mars 2018.

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


  • S. P. Babailov, E. V. Peresypkina, Y. Journaux, et K. E. Vostrikova, « Nickel(II) complex of a biradical: Structure, magnetic properties, high NMR temperature sensitivity and moderately fast molecular dynamics », Sensors and Actuators B: Chemical, vol. 239, p. 405-412, 2017.

  • A. Conte-Daban, V. Borghesani, S. Sayen, E. Guillon, Y. Journaux, G. Gontard, L. Lisnard, et C. Hureau, « Link between Affinity and Cu(II) Binding Sites to Amyloid-β Peptides Evaluated by a New Water-Soluble UV–Visible Ratiometric Dye with a Moderate Cu(II) Affinity », Analytical Chemistry, vol. 89, nᵒ 3, p. 2155-2162, févr. 2017.
    Résumé : Being able to easily determine the Cu(II) affinity for biomolecules of moderate affinity is important. Such biomolecules include amyloidogenic peptides, such as the well-known amyloid-β peptide involved in Alzheimer’s disease. Here, we report the synthesis of a new water-soluble ratiometric Cu(II) dye with a moderate affinity (109 M–1 at pH 7.1) and the characterizations of the Cu(II) corresponding complex by X-ray crystallography, EPR, and XAS spectroscopic methods. UV–vis competition was performed on the Aβ peptide as well as on a wide series of modified peptides, leading to an affinity value of 1.6 × 109 M–1 at pH 7.1 for the Aβ peptide and to a coordination model for the Cu(II) site within the Aβ peptide that agrees with the one mostly accepted currently.
    Mots-clés : ERMMES, POLE 2.

  • A. Flambard, A. Sugahara, S. De, M. Okubo, A. Yamada, et R. Lescouëzec, « Probing the local structure of Prussian blue electrodes by 113Cd NMR spectroscopy », Dalton Transactions, vol. 46, nᵒ 19, p. 6159-6162, mai 2017.
    Résumé : We demonstrate that 113Cd NMR is a potent technique to monitor the local electronic and structural states of the Prussian blue electrode during Li+ intercalation, providing an atomic-scale insight into the reaction mechanism.
    Mots-clés : ERMMES, POLE 2.
    Pièce jointe Full Text PDF 354.8 ko (source)

  • J. - R. Jiménez, M. Tricoire, D. Garnier, L. - M. Chamoreau, J. von Bardeleben, Y. Journaux, Y. Li, et R. Lescouëzec, « A new {Fe4Co4} soluble switchable nanomagnet encapsulating Cs+: enhancing the stability and redox flexibility and tuning the photomagnetic effect. », Dalton Transactions, vol. 46, nᵒ 44, p. 15549–15557, nov. 2017.
    Résumé : We report a new cyanide-bridged Cs⊂{Fe4Co4} box, a soluble model of photomagnetic Prussian blue analogues (PBAs). The Cs+ ion has a high affinity for the box and can replace the K+ ion in the preformed K-cube. This exchange is kinetically impeded at room temperature but is accelerated by heating and using the 18-crown-6 ether. The inserted Cs+ ion confers a high robustness to the cube, which withstands boiling, as shown by variable-temperature NMR studies. The stability of this model complex in solution allows the probing of the electronic interaction between the alkali ion and the cyanide cage by using various techniques. These interactions are known to play a role in the photomagnetic behaviour of PBAs. Firstly, the 133Cs NMR spectroscopy proves that there is an electronic communication between the encapsulated alkali ion and the cyanide cage. The measured up-field signal, observed at ca. −200 ppm at 300 K, reveals that a certain amount of spin density is transferred through the bonds from the paramagnetic Co(II) ion to the encapsulated cation. Secondly, cyclovoltammetric studies show that the nature of the inserted ions affects the redox properties of the cage and influences the electronic communication between the metal ions. However, the differences in the electrochemical properties of the K-cube and the Cs-cube remain moderate. As the switching properties are influenced by the redox potential of the Fe and Co centers, similar photomagnetic behaviour is observed, with both of them being highly photomagnetic. This result contrasts strikingly with previous studies on the 3D polymeric PBAs, where the PBAs with a high amount of Cs+ show poor photomagnetic behaviour. In that case, cooperative behaviour likely influences the switching properties. Finally, EPR spectroscopy shows that the K-cube is more anisotropic than the Cs-cube. This difference is reflected in the changes occurring in the slow magnetic relaxation (single molecule magnet behaviour) observed in the two cubes.
    Mots-clés : ERMMES, POLE 2.

  • S. B. Moussa, H. Bachouâ, M. Gruselle, P. Beaunier, A. Flambard, et B. Badraoui, « Hybrid organic-inorganic materials based on hydroxyapatite structure », Journal of Solid State Chemistry, vol. 248, p. 171-177, avr. 2017.
    Résumé : The present article details the formation of calcium hydroxyapatite synthesized by the

    hydrothermal way, in presence of glycine or sarcosine. The presence of these amino-acids during the synthetic processes reduces the crystalline growthing through the formation of hybrid organic-inorganic species The crystallite sizes are decreasing and the morphology is modified with the increase of the amino-acid concentration.
    Mots-clés : ARC, ERMMES, Glycine, Hydrothermal synthesis, Hydroxyapatite, POLE 1, POLE 2, Sarcosine.

  • K. Shankar, A. Mondal, Y. Li, Y. Journaux, et J. B. Baruah, « Hydroxide-Bridged Mixed-Valence Tetranuclear Cobalt 4-Nitrophenol Inclusion Complex Showing Single Molecule Magnet Property », ChemistrySelect, vol. 2, nᵒ 26, p. 7792-7798, 2017.
    Résumé : Two tetranuclear hydroxide-bridged mixed-valence cobalt complexes, one having 4-nitrophenolate anions and other having 4-nitrophenol as guest, namely [(μ2-dea)2(phen)2Co2(μ3-OH)2Co2(phen)2](np)4•H2O (1), [(μ2-dea)2(phen)2Co2(μ3-OH)2 Co2(phen)2]Cl4•2Hnp•9H2O (2) (Hnp=4-nitrophenol, phen=1,10-phenanthroline, dea=di-deprotonated diethanolamine) were synthesized and structurally characterized. Complex cation of these two complexes are based on Co4O4(OH)2 units where two cobalt ions are in Co2+ and other two are in Co3+ oxidation states. Reaction of same set of reactants namely phen, Hnp and diethanolamine with cobalt nitrate in presence or absence of hydrochloric acid resulted complex 1 and 2 respectively. The two triply-bridging hydroxides of complex 1 are in identical environment, but the complex 2 has two triply-bridging hydroxides in slightly different environments having differences in Co-O(hydroxide) bond distances around them. Complex 2 is ferromagnetic and shows field induced Single Molecule Magnets (SMM) behavior.
    Mots-clés : ERMMES, Hydroxide-bridged complex, Magnetic properties, POLE 2, Single molecule magnet, Tetranuclear cobalt complex.
    Pièce jointe Full Text PDF 5.4 Mo (source)



  • 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, nov. 2015.
    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.
    Note Note
    <p>Castellano, Maria Ruiz-Garcia, Rafael Cano, Joan Ferrando-Soria, Jesus Pardo, Emilio Fortea-Perez, Francisco R. Stiriba, Salah-Eddine Barros, Wdeson P. Stumpf, Humberto O. Canadillas-Delgado, Laura Pasan, Jorge Ruiz-Perez, Catalina de Munno, Giovanni Armentano, Donatella Journaux, Yves Lloret, Francesc Julve, Miguel<br />Fortea-Perez, Francisco/B-7848-2014;<br />Pardo, Emilio/0000-0002-1394-2553; Armentano, Donatella/0000-0002-8502-8074</p>

  • 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, sept. 2015.
    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.
    Note Note
    <p>de Bellefeuille, David Orio, Maylis Barra, Anne-Laure Aukauloo, Ally Journaux, Yves Philouze, Christian Ottenwaelder, Xavier Thomas, Fabrice<br />Orio, Maylis/J-6355-2015; Ottenwaelder, Xavier/J-1801-2012<br />Orio, Maylis/0000-0002-9317-8005; Ottenwaelder, Xavier/0000-0003-4775-0303</p>
    Note Note
    <p>de Bellefeuille, David Orio, Maylis Barra, Anne-Laure Aukauloo, Ally Journaux, Yves Philouze, Christian Ottenwaelder, Xavier Thomas, Fabrice<br />Orio, Maylis/J-6355-2015; Ottenwaelder, Xavier/J-1801-2012<br />Orio, Maylis/0000-0002-9317-8005; Ottenwaelder, Xavier/0000-0003-4775-0303</p>

  • 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, sept. 2015.
    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.
    Note Note
    <p>Grancha, Thais Mon, Marta Lloret, Francesc Ferrando-Soria, Jesus Journaux, Yves Pasan, Jorge Pardo, Emilio<br />Pardo, Emilio/C-9519-2013;<br />Pardo, Emilio/0000-0002-1394-2553</p>

  • A. Paquirissamy, A. R. Ruyack, A. Mondal, Y. Li, R. Lescouëzec, C. Chanéac, 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, 2015.

  • Y. Prado, N. Daffé, A. Michel, T. Georgelin, N. Yaacoub, J. M. Grenèche, 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, déc. 2015.
    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.
    Note Note
    <p>Prado, Yoann Daffe, Nieli Michel, Aude Georgelin, Thomas Yaacoub, Nader Greneche, Jean-Marc Choueikani, Fadi Otero, Edwige Ohresser, Philippe Arrio, Marie-Anne Cartier-dit-Moulin, Christophe Sainctavit, Philippe Fleury, Benoit Dupuis, Vincent Lisnard, Laurent Fresnais, Jerome</p>

  • 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, 2015.
    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, cluster compounds, E-POM, ERMMES, Heterocycles, MACO, Metallacycles, 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, avr. 2015.
    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.


  • 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, oct. 2014.
    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, nov. 2014.
    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 : ERMMES, POLE 2.
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