Robust ionic liquid@MOF composite as a versatile superprotonic conductor.

A highly performing proton conducting composite was prepared through the impregnation of EMIMCl ionic liquid in the mesoporous MIL-101(Cr)-SO3H MOF. The resulting EMIMCl@MIL-101(Cr)-SO3H composite displays high thermal and chemical stability, alongside retention of a high amount of EMIMCl even at temperatures as high as 500 K, as well as under moisture conditions. Remarkably, this composite exhibits outstanding proton conductivity not only at the anhydrous state (σ473 K = 1.5 × 10-3 S cm-S) but also under humidity (σ(343 K/60%-80%RH) ≥ 0.10 S cm-1) conditions. This makes EMIMCl@MIL-101(Cr)-SO3H a unique candidate to act as a solid state proton conductor for PEMFC applications under versatile conditions.

Fluorescent Zr(IV) Metal-Organic Frameworks Based on an Excited-State Intramolecular Proton Transfer-Type Ligand.

We report here the preparation of a series of Zr(IV) metal-organic frameworks (MOFs) of the MIL-140 structure type incorporating a ligand exhibiting an intense excited-state intramolecular proton transfer (ESIPT) fluorescence. These solids were obtained by systematically varying the substitution rate of 4,4'-biphenyldicarboxylate by 2,2'-bipyridine-3,3'-diol-5,5'-dicarboxylate, and they were thoroughly characterized by complementary techniques, including high-resolution powder X-ray diffraction, solid-state NMR spectroscopy, nitrogen sorption experiments, and time-resolved fluorescence. We show that the incorporation of the ESIPT-type ligand induces an increase of the hydrophilicity, leading ultimately to a higher sensitivity toward hydrolysis, a phenomenon rarely observed in this structure type, which is considered as one of the most stable among the Zr carboxylate MOFs. Eventually, optimization of the amount of fluorescent ligand within the structure allowed combining a decent microposity ( SBET > 750 m2·g-1) and a high stability even in boiling water, together with a high fluorescence quantum yield (>30%).

Reinvestigation of the M(II) (M = Ni, Co)/tetrathiafulvalenetetracarboxylate system using high-throughput methods: isolation of a molecular complex and its single-crystal-to-single-crystal transformation to a two-dimensional coordination polymer.

A high-throughput methodology combined with X-ray powder diffraction measurements was used to investigate the reactivity of the TetraThiaFulvalene TetraCarboxylic acid ((TTF-TC)H(4)) with divalent metals (M = Ni, Co) under various reaction conditions (stoichiometry, pH, temperature). Two new crystalline phases were identified and then studied by single crystal X-ray diffraction. Whereas the first one appears to be a simple salt, the second one, formulated {[M(H(2)O)(4)](2)(TTF-TC)}·4H(2)O, is built of 2:1 M:TTF-TC molecular complexes and labeled MIL-136(Ni, Co) (MIL stands for Materials Institute Lavoisier). The combination of thermogravimetric analysis and thermodiffraction studies reveals that MIL-136(Ni) exhibits a complex dehydration behavior. Indeed, a partial dehydration/rehydration process led to the single-crystal-to-single-crystal transformation of the molecular compound in a two-dimensional coordination polymer formulated {[Ni(2)(H(2)O)(5)(TTF-TC)]}·H(2)O (MIL-136'(Ni)). Magnetic and redox properties of MIL-136(Ni, Co) were investigated. Magnetic measurements indicate that all the magnetic coupling, intra- and intermolecular, are very weak; thus, the magnetic data of MIL-136(Ni, Co) have been interpreted in term of single-ion spin orbit coupling. Solid state cyclic voltammetry of MIL-136(Ni, Co) presents three reversible waves which were assigned to the redox activity of the TTF core and the metallic cations. In contrast to solids based on TTF linkers and alkaline ions, the MIL-136(Ni, Co) complexes do not act as excellent positive electrode materials for Li batteries, but present two reversible electron oxidation of the TTF core. These observations were tentatively related to the strength of the metal-carboxylate bond.

Bulk homochirality of a 3-D inorganic framework: ligand control of inorganic network chirality.

Enantioselective synthesis of a 3-D inorganic net has been achieved leading to metal-organic frameworks built from cobalt-oxide helices in which handedness is controlled by the chirality of the linked ligand.

The role of temperature in the synthesis of hybrid inorganic-organic materials: the example of cobalt succinates.

Five different cobalt succinate materials synthesized from an identical starting mixture using temperature as the only independent variable show increasing condensation and density at higher synthesis temperatures.

The first 3-D ferrimagnetic nickel fumarate with an open framework: [Ni3(OH)2(O2C-C2H2-CO2)(H2O)4].2H2O.

A three-dimensional nickel fumarate has been isolated by hydrothermal reaction and its structure solved from powder X-ray diffraction; its organisation reveals an unusual topology not previously seen in nickel chemistry and provided a scarce ferrimagnetic behaviour below 20 K.