[Cd(O2C(CH2)2CO2)]: An unprecedented 3D hybrid organic–inorganic topology

International audienc

The first 3D malonate bridged copper [Cu(O2C-CH2-CO2H)(2) center dot 2H(2)O]: Structure, properties and electronic structure

International audienceA new inorganic-organic compound [Cu(O2C-CH2-CO2H)2*2H2O] ([Cumal]) was hydrothermally synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffraction. [Cumal] is the first three-dimensional compound existing in the system Cu(II)-malonic acid-H2O. Its framework is built up through carboxyl bridged copper where CuO6 octahedra are elongated with an almost D4h symmetry (4+2) due to the Jahn-Teller effect. The magnetic properties were studied by measuring its magnetic susceptibility in the temperature range of 2-300 K indicating the existence of weak ferromagnetic interactions. The electronic structure of [Cumal] was calculated within the density functional theory (DFT) framework. Structural features are well reproduced using DFT structural optimizations and the optical spectra, calculated within the dielectric formalism, explain very well the light blue colour of the compound. It is shown that a GGA+U approach with a Ueff value of about 6 eV is necessary for a better correlation with the experiment

Elaboration of nickel nanoparticles by modified polyol process and their spark plasma sintering, characterization and magnetic properties of the nanoparticles and the dense nano-structured material

International audienceWell crystallized nickel nanoparticles with various diameters were prepared by modified polyol process in the presence of sodium hypophosphite as reducing agent. Dense nano-structured (DNS) samples of these nanopowders were obtained using the spark plasma sintering technique. Magnetic characteristics of the powders and the dense samples were studied through the zero-field-cooling (ZFC)/field-cooling (FC) and the hysteresis measurements. Irreversibility in the (ZFC/FC) curves was observed for all samples and could be interpreted in terms of the unblocking of magnetization for the nanoparticles with diameter below 50nm and domain wall depinning for the nanoparticles with diameter above 50nm and for the DNS samples. Compared with bulk nickel, the nanoparticles and the DNS samples exhibited an enhanced coercivity and a decreased saturation magnetization; the relatively elevated value of the coercivity especially for the Ni nanoparticles could be due to their anisotropic morphology and their small size. The low values of the saturation magnetization could result from the inevitable surface oxidation of the powder

Age modulates Fe3O4 nanoparticles liver toxicity: dose-dependent decrease in mitochondrial respiratory chain complexes activities and coupling in middle-aged as compared to young rats.

International audienc

Biomed Res Int

We examined the effects of iron oxide nanoparticles (IONPs) on mitochondrial respiratory chain complexes activities and mitochondrial coupling in young (3 months) and middle-aged (18 months) rat liver, organ largely involved in body iron detoxification. Isolated liver mitochondria were extracted using differential centrifugations. Maximal oxidative capacities (V(max), complexes I, III, and IV activities), V(succ) (complexes II, III, and IV activities), and V tmpd, (complex IV activity), together with mitochondrial coupling (V(max)/V0) were determined in controls conditions and after exposure to 250, 300, and 350 mu g/ml Fe3O4 in young and middle-aged rats. In young liver mitochondria, exposure to IONPs did not alter mitochondrial function. In contrast, IONPs dose-dependently impaired all complexes of the mitochondrial respiratory chain in middle-aged rat liver: V(max) (from 30 +/- 1.6 to 17.9 +/- 1.5; P < 0.001), V(succ) (from 33.9 +/- 1.7 to 24.3 +/- 1.0; P < 0.01), V(tmpd) (from 43.0 +/- 1.6 to 26.3 +/- 2.2 micromol O2/min/g protein; P < 0.001) using Fe3O4 350 microg/ml. Mitochondrial coupling also decreased. Interestingly, 350 mu g/ml Fe3O4 in the form of Fe(3+) solution did not impair liver mitochondrial function in middle-aged rats. Thus, IONPs showed a specific toxicity in middle-aged rats suggesting caution when using it in old age