Reaction of cerium ammonium nitrate and tetrafluoroterephthalic acid in water afforded two new metal-organic frameworks with UiO-66 [F4_UiO-66(Ce)] and MIL-140 [F4_MIL-140A(Ce)] topologies. The two compounds can be obtained in the same experimental conditions, just by varying the amount of acetic acid used as crystallization modulator in the synthesis. Both F4_UiO-66(Ce) and F4_MIL-140A(Ce) feature pores with size < 8 Å, which classifies them as ultramicroporous. Combination of X-ray photoelectron spectroscopy and magnetic susceptibility measurements revealed that both compounds contain a small amount of Ce(III), which is preferentially accumulated near the surface of the crystallites. The CO2 sorption properties of F4_UiO-66(Ce) and F4_MIL-140A(Ce) were investigated, finding that they perform better than their Zr-based analogues. F4_MIL-140A(Ce) displays an unusual S-shaped isotherm with steep uptake increase at pressure < 0.2 bar at 298 K. This makes F4_MIL-140A(Ce) exceptionally selective for CO2 over N2: the calculated selectivity, according to the ideal adsorbed solution theory for a 0.15:0.85 mixture at 1 bar and 293 K, is higher than 1900, amongst the highest ever reported for metal-organic frameworks. The calculated isosteric heat of CO2 adsorption is in the range of 38-40 kJ mol-1 , indicating a strong physisorptive character. CeO(TFBDC)•H2O [F4_MIL-140A(Ce)] 548 mg (1mmol) of cerium ammonium nitrate [(NH4)2Ce(NO3)6), CAN] and 238 mg (1 mmol) of tetrafluoroterephthalic acid (H2TFBDC) were dissolved in 50 ml of deionized (DI) water in a round bottom flask. The solution was heated to 110 °C under stirring and refluxed for 24 h. The obtained yellow solid was collected and washed three times with DI water and once with acetone. The solid was then dried in oven at 80 °C for 24 h. Yield: 73% (calculated on the basis of Ce). Elemental analysis: C = 22.7% exp. (23.4% calc.), H = 0.76% exp. (0.49% calc.) CeO0.67(OH)0.67(TFBDC)•3H2O [F4_UiO-66(Ce)] 548 mg (1 mmol) of CAN, 238 mg (1 mmol) of H2TFBDC and 6 mL (100 mmol) of acetic acid were dissolved in 45 ml of DI water in a round bottom flask. The solution was heated to 110 °C under stirring and refluxed for 24 h. The obtained yellow solid was collected and washed three times with DI water and once with acetone. The solid was then dried in oven at 80 °C for 24 h. Yield: 66% (calculated on the basis of Ce). Elemental analysis: C = 23.5% exp. (22.6% calc.), H = 2.19% exp. (1.57% calc.) Analytical procedures Powder X-Ray Diffraction (PXRD). PXRD patterns were collected in reflection geometry with a 40 s step-1 counting time and with a step size of 0.016° 2θ on a PANalytical X'PERT PRO diffractometer, PW3050 goniometer, equipped with an X'Celerator detector by using the Cu Kα radiation. The long fine focus (LFF) ceramic tube operated at 40 kV and 40 mA. The pattern

Metal-organic frameworks (MOFs) have gained widespread attention due to their modular construction that allows the tuning of their properties. Within this vast class of compounds, metal carboxylates containing tri- and...

Mixed membrane matrices (MMMs) made up with Nafion and nanocrystals of zirconium metal-organic framework (MOF) UiO-66 or the analogous sulfonated SOH-UiO-66 were prepared by varying the filler loading and the size of the crystals. The combined effects of size and loading, together with the presence of sulfonic groups covalently linked to the MOFs, were studied with regard to the conductivity and mechanical properties of the obtained composite matrices. A large screening of membranes was preliminarily made and, on the most promising samples, an accurate conductivity study at different relative humidities and temperatures was also carried out. The results showed that membranes containing large crystals (200 nm average size) in low amounts (around 2%) displayed the best results in terms of proton conductivity values, reaching values by 30% higher than those of pure Nafion, while leaving the mechanical properties substantially unchanged. On the contrary, MMMs containing MOFs of small size (20 nm average size) did not show any conductivity improvements if compared to pure Nafion membranes. The effect of MOF sulfonation was negligible at low filler loading whereas it became important at loading values around 10%. Finally, membranes with a high filler loading (up to 60 wt %) of sulfonated UiO-66 showed a slight reduction of conductivity in comparison with membranes loaded at 20% of nonsulfonated ones.

A near solvent-free synthetic route for Ce-UiO-66 metal-organic frameworks (MOFs) is presented. The MOFs are obtained by simply grinding the reagents, cerium ammonium nitrate (CAN) and the carboxylic linkers, in a mortar for few minutes with the addition of a small amount of acetic acid (AcOH) as modulator (8.75 eq, o.5 mL). The slurry is then transferred into a 2 mL vial and heated at 120 °C for 1 day. The MOFs have been characterized for their composition, crystallinity and porosity and employed as heterogeneous catalysts for the photo-oxidation reaction of substituted benzylic alcohols to benzaldaldehydes under near ultraviolet light irradiation. The catalytic performances, such as selectivity, conversion and kinetics, exceed those of similar systems studied by chemical oxidation using similar Ce-MOFs as catalyst. Moreover, the MOFs were found to be reusable up to three cycles without loss of activity. Density functional theory (DFT) calculations were used in order to fully describe the electronic structure of the best performing MOFs and to provide useful information on the catalytic activity experimentally observed. 8 ASSOCIATED CONTENT Supporting Information available. Synthetic and analytical procedures, experimental and instrumental details, TGA curves, UV-Vis, FT-IR and 1 H-NMR spectra, additional catalytic data, additional XRPD patterns, theoretical calculations details. This material is available free of charge via the Internet at http://pubs.acs.org.

The development of efficient water oxidation catalysts (WOCs) is of key importance in order to drive sustainable reductive processes aimed at producing renewable fuels. Herein, two novel dinuclear complexes, [(Cp*Ir)2(μκ 3 -O,N,O-H4-EDTMP)] (Ir-H4-EDTMP, H4-EDTMP 4− = ethylenediamine tetra(methylene phosphonate)) and [(Cp*Ir)2(μ-κ 3 -O,N,O-EDTA)] (Ir-EDTA, EDTA 4− = ethylenediaminetetraacetate), were synthesized and completely characterized in solution, by multinuclear and multidimensional NMR

We report on the results of an in situ synchrotron powder X‐ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated CeIV‐based metal–organic frameworks (MOFs), analogues of the already well investigated ZrIV‐based UiO‐66 and MIL‐140A, namely, F4_UiO‐66(Ce) and F4_MIL‐140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as reagents, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds, varying parameters such as temperature, amount of the protonation modulator nitric acid and amount of the coordination modulator acetic acid. When only HNO3 is present in the reaction environment, only F4_MIL‐140A(Ce) is obtained. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C. Upon addition of AcOH to the system, alongside HNO3, mixed‐phased products are obtained. F4_UiO‐66(Ce) is always formed faster, and no interconversion between the two phases occurs. In the case of F4_UiO‐66(Ce), crystal growth is always the rate‐determining step. A higher amount of HNO3 favours the formation of F4_MIL‐140A(Ce), whereas increasing the amount of AcOH favours the formation of F4_UiO‐66(Ce). Based on the in situ results, a new optimised route to achieving a pure, high‐quality F4_MIL‐140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

We report a novel synthetic procedure for the high-yield synthesis of metal–organic frameworks (MOFs) with fcu topology with a UiO-66-like structure starting from a range of commercial Zr IV precursors and various substituted dicarboxylic linkers. The syntheses are carried out by grinding in a ball mill the starting reagents, namely, Zr salts and the dicarboxylic linkers, in the presence of a small amount of acetic acid and water (1 mL total volume for 1 mmol of each reagent), followed by incubation at either room temperature or 120 °C. Such a simple “shake ‘n bake” procedure, inspired by the solid-state reaction of inorganic materials, such as oxides, avoids the use of large amounts of solvents generally used for the syntheses of Zr-MOF. Acidity of the linkers and the amount of water are found to be crucial factors in affording materials of quality comparable to that of products obtained under solvo- or hydrothermal conditions.

Single phase mixed zirconium phosphate phenylphosphonates, ZrP(PP)x, were prepared by two different synthetic approaches: reaction of gels of nanosized α-zirconium phosphate in propanol with solutions of phenylphosphonic acid (H2PP), leading to the topotactic exchange of monohydrogen phosphate groups with phenylphosphonate groups, and precipitation from propanol solutions of H2PP, phosphoric acid, and zirconyl propionate. In both cases, propanol intercalated compounds were obtained. The x values of the ZrP(PP)x materials prepared by topotactic anion exchange ranged from 0.37 to 0.56 for (H2PP/Zr) molar ratios in the range 0.52-4.16 and [H2PP] = 0.1 M, while a maximum x value of 0.73 was only reached at 60 °C, with (H2PP/Zr) = 4.16 and [H2PP] = 0.31 M. Direct precipitation of ZrP(PP)x provided samples with 0.13 ≤ x ≤ 1.54, for H2PP molar fractions in the range 0.05-0.5 and (P/Zr) molar ratio = 6. At 90% relative humidity, the (H2O/Zr) molar ratio for the precipitated ZrP(PP)x powder samples increased in the range 1.3-3.0 with increasing x and resulted in being higher than that of nanosized ZrP (0.8). The analysis of the X-ray diffraction patterns of the gel and powder samples, together with the hydration data of the powder samples, suggested a structural model in which the random distribution of the phosphate and phenylphosphonate groups creates cavities which can accommodate propanol molecules in the gel samples and water molecules in the hydrated powder samples.