In recent years the search for new open-framework materials with transition metal elements has become the focus of much interest due to the potential application of these materials as absorbents, ion exchangers, solid-state electrolytes, and catalysts in heterogeneous catalysis.[1] Such applications are not possible with main group systems of tetrahedral framework zeolites. The syntheses of these materials usually involve organic templates, for example organic diamines, for generating large cavities and are performed under mild hydrothermal conditions to avoid the formation of dense phases.Microporous behavior has been successfully extended to the phosphate and arsenate systems of at least 14 elements of the periodic table, but examples dealing with chromium have not been reported. [1b, 2] The pattern of behavior of these kinds of compounds is underpinned by the strength of the PÀO ZUSCHRIFTEN

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Compounds with the general formula [MM‘(C3H2O4)2(H2O)4] (M = Ba, Sr; M‘ = Cu, Mn; C3H2O4 = malonate) have been synthesized and characterized. Single-crystal X-ray diffraction study on the [SrCu(C3H2O4)2(H2O)4] compound indicates that it crystallizes in the orthorhombic space group, Pccn, Z = 4, with unit cell parameters a = 6.719(2), b = 18.513(7), and c = 9.266(4) Å. The structure consists of distorted octahedral copper(II) species which are extended along the ac plane forming a two-dimensional structure. The geometry of the alkaline-earth ions resembles a distorted antiprism. The other compounds are isostructural. The EPR spectra of the [MCu(C3H2O4)2(H2O)4] (M = Ba, Sr) compounds show an orthorhombic g tensor as consequence of a linear combination of the axial symmetry and the exchange interactions between magnetically different centers, but crystallographically equivalent. For the manganese compounds, the EPR spectra of polycrystalline samples show that the intensity of the signal increases with decreasing temperature down to 20 K, and at lower temperatures the intensity decreases, becoming silent below 7 K. Magnetic measurements show two-dimensional (2D) ferromagnetic and antiferromagnetic interactions for the copper and manganese phases, respectively. In all cases, the susceptibility data were fitted by the expression for a Heisenberg square-planar system. The obtained J/k values are 1.44 and 1.15 K, for the SrCu and BaCu compounds, respectively, and −0.65 and −0.59 K for the SrMn and BaMn compounds, respectively. For the manganese compounds, magnetic measurements show a magnetic ordering below 5 K which confirms the presence of a weak ferromagnetism. Thermal analyses of the phases show three different decomposition steps:  dehydration, ligand pyrolysis, and evolution of the inorganic residue for all compounds. Taking these results into account, we performed further thermal treatments to obtain mixed oxides. These were obtained at short reaction times and at temperatures lower than those of the conventional ceramic method.

Poly(vinylidene fluoride) (PVDF) and MOF-808-based separators for lithium-ion batteries (LIBs) have been prepared and fully characterized in terms of morphological and thermal properties, electrolyte uptake, and retention, and surface hydrophilic characteristics. The effect of PVDF/MOF-808 separators on the electrochemical performance of LIBs has been evaluated. The PVDF/MOF-808 membranes exhibit a well-defined porous structure with a uniform distribution of interconnected macro-to mesopores. The inclusion of the Zr-based MOF nanoparticles increases the porosity and surface area of the separator, enhancing the electrolyte uptake and the ionic conductivity. Finally, the presence of MOF-808 fillers improves the liquid electrolyte retention, which prevents the capacity fading at high C-rates cycling. Indeed, charge−discharge tests performed in Li/C-LiFePO 4 half-cells reveal a discharge capacity of 68 mAh•.g −1 at 2C-rate for PVDF/MOF-808 membranes, in comparison with the 0 mAh•g −1 obtained for pure PVDF. The PVDF/10 wt % MOF-808 sample shows a long-term stable cycling behavior with a Coulombic efficiency close to 100%. Thus, it is shown that the composite membranes represent an improvement with respect to conventional separators for lithium ion battery applications, since they coupled the polymer meso-and macroporous structure with the wellordered microporous system of the MOFs, which improve significantly the electrolyte affinity.