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The new microporous metal organic framework [La2(H2O)5(H2TPPE)]·3H2O (CAU‐54), is obtained in a hydrothermal reaction of the linker 1,1,2,2‐tetrakis(4′‐phosphonophenyl)ethylene (H8TPPE) and La3+ ions. The extensive characterization including temperature‐dependent crystal structures and spectroscopic properties allowed to understand the unique, multi‐responsive material properties. CAU‐54 exhibits rarely observed reversible photochromism as well as turn‐on photoluminescence by various external chemical or physical stimuli including change of pressure, solvent exchange, and temperature variation. These properties can be unequivocally assigned to the presence of tetraphenylethylene (TPE) moieties of the linker molecules within the MOF, i.e., the ordered spatial arrangement of the linker molecules, the presence of accessible pores as well as the coordination flexibility of the phosphonate groups and the rotational freedom of the linker. By temperature‐dependent steady‐state and time‐resolved luminescence studies, it is shown that this compound exhibits a) blue fluorescence that becomes effectively quenched at room temperature, b) green efficient luminescence with thermal stability up to 400 K, and c) red phosphorescence correlated to the observed photochromism. In addition, CAU‐54 shows unusual thermal expansion properties as shown by temperature‐dependent powder X‐ray diffraction measurements with identified transition points that correlate with the observed temperature‐dependent changes in the photoluminescence. [ABSTRACT FROM AUTHOR]

Cerium‐based Metal‐Organic frameworks (Ce‐MOFs) are attracting increasing interest due to their similar structural features to zirconium MOFs. The redox behavior of Ce(III/IV) adds a range of properties to the compounds. Recently, perfluorinated linkers have been used in the synthesis of MOFs to introduce new characteristic into the structure. We report the synthesis and structural characterization of Ce(IV)‐based MOFs constructed using two perfluorinated alkyl linkers. Their structure, based on hexanuclear Ce6O4(OH)412+ clusters linked to each other by the dicarboxylate ions, has been solved ab‐initio from X‐ray powder diffraction data and refined by the Rietveld method. The crystallization kinetics and the MOF formation mechanism was also invesitigated by Synchrotron radiation with XAS spectroscopies (EXAFS and XANES). The MOFs present the same fcu cubic topology as observed in MOF‐801 and UiO‐66, and they showed good stability in water at different pH conditions. The electronic structure of these MOFs has been studied by DFT calculations in order to obtain insights into the density of states structure of the reported compounds, resulting in band gaps in the range of 2.8–3.1 eV. Their catalytic properties were tested both thermally and under visible light irradiation for the degradation of methyl orange (MO) dye. [ABSTRACT FROM AUTHOR]

Herein, we report two new COOH‐functionalized metal‐organic frameworks (MOFs) of composition [M6O4(OH)6(PMA)2(H2PMA)]×H2O, M=Zr, Hf), denoted CAU‐61, synthesized by using pyromellitic acid (H4PMA), a tetracarboxylic acid, as the linker and acetic acid as the solvent. The structure was determined from powder X‐ray diffraction data and one‐dimensional inorganic building units are connected through tetracarboxylate as well as dicarboxylate linker molecules, resulting in highly stable microporous framework structures with limiting and maximum pore diameter of ∼3.6 and ∼5.0 Å, respectively, lined with −COOH groups. Thermal stabilities of up to 400 °C in air, chemical stability in water at pH 1 to 12 and water uptake of 17 mol/mol prompted us to study the proton exchange of the μ2‐OH, μ3‐OH of the IBU and −COOH groups of the linker by titration with LiOH. Comparison of the pKa values with three UiO‐66 derivatives confirms distinct pKa value ranges and trends for the different acidic protons. Furthermore, the preparation of Zr−CAU‐61 membranes and first results on permeation of dyes and ions in aqueous solutions are presented. [ABSTRACT FROM AUTHOR]

The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24(OH)56(CH3COO)12]X4, denoted CAU‐55‐X, with X=Cl−, Br−, I−, HSO4−. Three‐dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24(OH)56(CH3COO)12]Cl4 in water were established resulting in high yields (>95 %, 215 g per batch) within minutes. Specific surface areas and H2O capacities with maximum values of up to 930 m2 g−1 and 430 mg g−1 are observed. The particle size of CAU‐55‐X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly‐ and perfluoroalkyl substances (PFAS). [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A concept for obtaining isoreticular compounds with tri‐ instead of tetravalent metal cations using highly acidic reaction conditions was developed and successfully applied in a high throughput study using N,N′‐piperazinebis(methylenephosphonic acid) (H4PMP), that resulted in the discovery of a new porous aluminium phosphonate denoted CAU‐60⋅6 HCl. The high‐throughput study was subsequently extended to other trivalent metal ions. Al‐CAU‐60⋅6 HCl demonstrates reversible desorption of HCl (18.3 wt % loading) with three distinct compositions observed with zero, four or six HCl molecules per formula unit. Structural changes were followed in detail by powder X‐ray diffraction, EDX analysis as well as IR spectroscopy. Rapid desorption of HCl in water within minutes and subsequent adsorption from the gas phase and from aqueous solution are shown. Furthermore, it is possible to adsorb HBr into the guest free Al‐CAU‐60 framework, demonstrating the high stability of this compound. [ABSTRACT FROM AUTHOR]

The tetraphosphonic acid 1,1,2,2‐tetrakis(4‐phosphonophenyl)ethylene (H8L) was used as linker in the synthesis of eight new isostructural, phosphonate‐based metal‐organic frameworks of composition [M2(H2O)2(H2L)] ⋅ xH2O (M=Y3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; 1.5

The use of the linker molecule benzene‐1,3‐diphosphonic acid (H4L) and V4+‐ions in a hydrothermal synthesis without further additives led to the discovery of a new coordination polymer of composition [(VO)2(H2O)4(L)] ⋅ 2H2O. The structure of the compound was solved by direct methods from powder X‐ray diffraction data and refined using the Rietveld method. The compound was thoroughly characterized showing a reversible amorphization upon reduced pressure or high temperatures. A potential porosity was calculated, but could not be verified by H2O‐adsorption experiments. [ABSTRACT FROM AUTHOR]

The report is the first broader evaluation of the gas sorption properties of CAU‐23 for the adsorptives CO2, H2, CH4, and SO2. CAU‐23 is of intermediate porosity among Al‐MOFs with specific BET surface areas of the order of MIL‐100>MIL‐53>CAU‐23>MIL‐160>MIL‐53‐TDC>Alfum>CAU‐10‐H and total pore volumes of the order of MIL‐100>MIL‐53>CAU‐23>Alfum=MIL‐160>MIL‐53‐TDC>CAU‐10‐H. CO2 uptake (3.97 mmol g−1, 293 K) and H2 uptake (10.25 mmol g−1, 77 K) of CAU‐23 are second in the series and only slightly smaller than for MIL‐160. The CH4 uptake of CAU‐23 (0.89 mmol g−1, 293 K) is unremarkable in comparison with the other Al‐MOFs. The SO2 uptake (8.4 mmol g−1, 293 K) follows the porosity and higher SO2 uptakes were only observed for MIL‐53 and MIL‐100. CAU‐23 is one of the best Al‐MOFs for high‐pressure sorption of CO2, with an uptake of 33 wt.‐% at 20 bar, 293 K. Gas sorption measurements at two different temperatures gave near zero‐coverage enthalpy of adsorptions, ▵Hads0 for CO2 of −22 kJ mol−1 and of SO2 for −38 kJ mol−1 which is at the low end of the other Al‐MOFs (−22 to −39 kJ mol−1 for CO2; −41 to −51 kJ mol−1 for SO2), yet ▵Hads increases for CAU‐23 with CO2 and SO2 to −25 and −57 kJ mol−1, respectively. For CO2/CH4 and SO2/CO2 separation, ideal adsorbed solution theory (IAST) predicted gas selectivities of 5 and 27–50 (depending on molar ratio and model), respectively, in line with 4.5–6.3 and 17–50, respectively, with most of the other Al‐MOFs, where only MIL‐53‐TDC with 83 and MIL‐160 with 126 gave a higher SO2/CO2 selectivity at a molar ratio of 0.5. [ABSTRACT FROM AUTHOR]

Two different metal‐organic frameworks containing 2,5‐pyrazinedicarboxylate (PzDC2−) as linker molecule and hexanuclear {Hf6(μ3‐O)4(μ3‐OH)4} clusters were obtained under solvothermal reaction conditions at 120 °C. Formic acid as the solvent leads to the formation of Hf‐UiO‐66‐PzDC ([Hf6(μ3‐O)4(μ3‐OH)4(OH)4(H2O)4(PzDC)4]), while the reaction in a water/formic acid mixture resulted in the crystallisation of Hf‐CAU‐22‐PzDC ([Hf6(μ3‐O)4(μ3‐OH)4(μ‐OH)2(OH)4(H2O)4(PzDC)3]). The UiO‐66 compound is a new member of the large class of UiO‐66‐type MOFs. Hf‐CAU‐22 contains a chain of condensed {Hf6O4(OH)4(μ‐OH)4} clusters as the IBU, which is new to Hf‐MOF chemistry. For both MOFs, a detailed characterization, i. e. structure refinement from powder X‐ray diffraction data, 1H‐NMR‐spectroscopy, elemental and thermogravimetric analyses and N2 sorption measurements, was carried out. Hf‐UiO‐66‐PzDC undergoes a dehydration around 215 °C and framework decomposition starts at 315 °C. From N2 sorption measurements, a maximum BET surface area of 460 m2/g was determined. The dehydration of Hf‐CAU‐22‐PzDC starts at 200 °C and the framework decomposition at 325 °C. The BET surface area was determined to 170 m2/g. [ABSTRACT FROM AUTHOR]

The reaction of the V‐shaped linker molecule 5‐hydroxyisophthalic acid (H2L0), with Al or Ga nitrate under almost identical reaction conditions leads to the nitration of the linker and subsequent formation of metal–organic frameworks (MOFs) with CAU‐10 or MIL‐53 type structure of composition [Al(OH)(L)], denoted as Al‐CAU‐10‐L0, 2, 4, 6 or [Ga(OH)(L)], denoted as Ga‐MIL‐53‐L2. The Al‐MOF contains the original linker L0 as well as three different nitration products (L2, L4 and L4/6), whereas the Ga‐MOF mainly incorporates the linker L2. The compositions were deduced by 1H NMR spectroscopy and confirmed by Rietveld refinement. In situ and ex situ studies were carried out to follow the nitration and crystallization, as well as the composition of the MOFs. The crystal structures were refined against powder X‐ray diffraction (PXRD) data. As anticipated, the use of the V‐shaped linker results in the formation of the CAU‐10 type structure in the Al‐MOF. Unexpectedly, the Ga‐MOF crystallizes in a MIL‐53 type structure, which is usually observed with linear or slightly bent linker molecules. To study the structure directing effect of the in situ nitrated linker, pure 2‐nitrobenzene‐1,3‐dicarboxylic acid (m‐H2BDC‐NO2) was employed which exclusively led to the formation of [Ga(OH)(C8H3NO6)] (Ga‐MIL‐53‐m‐BDC‐NO2), which is isoreticular to Ga‐MIL‐53‐L2. Density Functional Theory (DFT) calculations confirmed the higher stability of Ga‐MIL‐53‐L2 compared to Ga‐CAU‐10‐L2 and grand canonical Monte Carlo simulations (GCMC) are in agreement with the observed water adsorption isotherms of Ga‐MIL‐53‐L2. [ABSTRACT FROM AUTHOR]

A systematic study of the systems M2+/H4L/KOH/H2O, with M2+ =Mg2+, Ca2+, Sr2+, Ba2+ and H4L=N,N'-4,4'-bipiperidine-bis (methylenephosphonic acid) was carried out using highthroughput methods, including a temperature gradient oven. Overall, six new alkaline earth phosphonates were discovered and structurally characterised by single-crystal and powder Xray diffraction. At room temperature the compounds of composition [Mg2(H2O)8(L)] (1), [Ca2(H2O)6(L)] (2), [Sr2(H2O)4(L)] (3) and [Ba2(H2O)9(L)]·H2O (4) were discovered. They exhibit the same metal to linker ratio, but differ in their water content. Distinct structural changes are observed with an increase in dimensionality of the coordination polymer with increasing ionic radius of the metal ion. At elevated reaction temperatures the two new metal phosphonates [Mg2(H2O)5(L)] (5) and [Ba2(H2O)2(L)] ·2 H2O (6) were obtained either from the same reaction mixture as for 1 and 4, respectively, or by solid state transformation. The detailed characterisation of the all materials is also reported. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Two new isostructural porous coordination polymers (CPs) were obtained under solvothermal reaction conditions using 2,5‐dihydroxy‐p‐benzoquinone (H2DHBQ) or 1,2,4,5‐tetrahydroxybenzene (H4THB) as linker molecule and Zr4+ or Hf4+ salts. Highly crystalline compounds with composition [M2(μ‐OH)2(DHBQ)3]·xH2O (M = Zr4+ or Hf4+, x = 0–3.6/3.3) were found in a wide temperature range (120–200 °C) and a reaction time of 70 h. The crystal structures were determined ab initio from powder X‐ray diffraction data and the oxidation state of the linker was confirmed spectroscopically. The dinuclear inorganic building unit M2O14 is new for Zr‐ and Hf‐CPs. For both compounds a full characterization was carried out, i.e. crystal structure determination, spectroscopic measurements, elemental‐ and thermogravimetric analyses. [M2(OH)2(DHBQ)3] (M = Zr4+ or Hf4+) is stable up to 250 and 220 °C, respectively. Water sorption measurements proofed an uptake of 3.6 mol H2O per mol and 3.3 mol H2O per mol, respectively. [ABSTRACT FROM AUTHOR]

A new gallium based metal‐organic framework, denoted as Ga‐MIL‐53‐FcDC, with the chemical formula [Ga(OH)(FeC12H8O4)] was synthesized using the ferrocene containing linker molecule 1,1'‐ferrocenedicarboxylic acid (H2FcDC, FeC12H10O4). The porous nature of the compound could be confirmed by nitrogen sorption and a specific surface area of 270 m2/g was determined. The persistence of the ferrocene complex inside the structure was confirmed by Mössbauer‐, EPR and UV/VIS‐spectroscopy. Ga‐MIL‐53‐FcDC shows structural flexibility depending on which guest molecule is located in the pores of the compound. The mechanism of structural flexibility was analyzed by means of powder X‐ray diffraction adsorbing pyrazine or iodine. The flexibility of the crystal structure can be attributed to the torsion of the GaO6 octahedra in the IBU respective to each other and the torsion of the carboxylate groups of FcDC2− relative to the aromatic ring. [ABSTRACT FROM AUTHOR]

A Zr‐based metal‐organic framework has been synthesized and employed as a catalyst for photochemical carbon dioxide reduction coupled with water oxidation. The catalyst shows significant carbon dioxide reduction property with concomitant water oxidation. The catalyst has broad visible light as well as UV light absorption property, which is further confirmed from electronic absorption spectroscopy. Formic acid was the only reduced product from carbon dioxide with a turn‐over frequency (TOF) of 0.69 h−1 in addition to oxygen, which was produced with a TOF of 0.54 h−1. No external photosensitizer is used and the ligand itself acts as the light harvester. The efficient and selective photochemical carbon dioxide reduction to formic acid with concomitant water oxidation using Zr‐based MOF as catalyst is thus demonstrated here. [ABSTRACT FROM AUTHOR]

A new scandium naphthalenedicarboxylate with the framework composition [Sc2(1,4‐NDC)3] (H2‐1,4‐NDC = 1,4‐naphthalenedicarboxylic acid) was obtained under hydrothermal synthesis conditions. A structure model could be developed by a combination of 3D electron diffraction measurements and computationally assisted structure determination, which was further validated by a good agreement with the experimental powder X‐ray diffraction pattern. The structure consists of isolated ScO6 octahedra interconnected by the carboxylate groups of linker molecules to form chains. These chains are connected by the naphthalene‐moieties to form a three‐dimensional framework with square‐shaped pores and the organic group pointing into the pores. Although very similar synthesis conditions were chosen, [Sc2(1,4‐NDC)3] is not isostructural to aluminum naphthalenedicarboxylate [Al(OH)(1,4‐NDC)], which crystallizes in a MIL‐53 type structure. This can be traced back to the different inorganic building units that are observed. The compound was thoroughly characterized by elemental analysis, IR spectroscopy, sorption measurements, thermogravimetric analysis and luminescence measurements. [Sc2(1,4‐NDC)3] exhibits a high thermal stability and a ligand‐based blue luminescence in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

Energy‐efficient indoors temperature and humidity control can be realised by using the reversible adsorption and desorption of water in porous materials. Stable microporous aluminium‐based metal–organic frameworks (MOFs) present promising water sorption properties for this goal. The development of synthesis routes that make use of available and affordable building blocks and avoid the use of organic solvents is crucial to advance this field. In this work, two scalable synthesis routes under mild reaction conditions were developed for aluminium‐based MOFs: (1) in aqueous solutions using a continuous‐flow reactor and (2) through the vapour‐assisted conversion of solid precursors. Fumaric acid, its methylated analogue mesaconic acid, as well as mixtures of the two were used as linkers to obtain polymorph materials with tuneable water sorption properties. The synthesis conditions determine the crystal structure and either the MIL‐53 or MIL‐68 type structure with square‐grid or kagome‐grid topology, respectively, is formed. Fine‐tuning resulted in new MOF materials thus far inaccessible through conventional synthesis routes. Furthermore, by varying the linker ratio, the water sorption properties can be continuously adjusted while retaining the sigmoidal isotherm shape advantageous for heat transformation and room climatisation applications. [ABSTRACT FROM AUTHOR]

Two new scandium‐containing coordination polymers, with the formulae {(CH3)2NH2}[Sc(BPDC)2] (1) and [Sc(OH) (BPyDC)] (2) were solvothermally synthesized by using the linear linker molecules biphenyl‐4,4'‐dicarboxylic acid (H2BPDC) and 2,2'‐bipyridine‐5,5'‐dicarboxylic acid (H2BPyDC). Crystal structures were determined from single‐crystal and powder X‐ray diffraction data, respectively. The crystal structures of 1 and 2 contain isolated ScO6 or chains of trans corner‐sharing ScO6 octahedra as the inorganic building unit (IBU), which are connected by the linker molecules to a 3D framework or a layered structure, respectively. The compounds were characterized by IR‐spectroscopy, elemental analysis, thermogravimetric analysis and photoluminescence spectroscopy. 1 shows blue emission at 400 nm, while 2 exhibits intense green emission at 550 nm with a high quantum yield (QY) of 69 %. [ABSTRACT FROM AUTHOR]

A new scandium metal‐organic framework (MOF) with the composition [Sc(OH)(SDBA)], denoted Sc‐CAU‐11, was synthesized under solvothermal reaction conditions using 4,4‐sulfonyldibenzoic acid (H2SDBA), as a V‐shaped linker molecule. The crystal structure was refined from powder X‐ray diffraction (PXRD) data employing the Rietveld method and using the structural model of the isostructural aluminium compound. Sc‐CAU‐11 crystallizes in the orthorhombic space group Pnma and is composed of chains of trans corner‐sharing ScO6 octahedra. The chains are connected by the linker molecules to form layers with intralayer porosity and an ABAB stacking sequence. Detailed characterization was carried out by elemental analysis, IR‐spectroscopy, thermogravimetric analysis, gas sorption and luminescence measurements. Sc‐CAU‐11 shows a high thermal stability up to 500 °C in air, which is confirmed by temperature‐depended PXRD measurements. The optical properties were tuned by substituting Sc3+ ions in Sc‐CAU‐11 with trivalent europium and terbium ions and strong temperature as well as excitation dependent optical emission is observed. [ABSTRACT FROM AUTHOR]

Herein is reported the utilization of acetonitrile as a new solvent for the synthesis of the three significantly different benchmark metal–organic frameworks (MOFs) CAU‐10, Ce‐UiO‐66, and Al‐MIL‐53 of idealized composition [Al(OH)(ISO)], [Ce6O4(OH)4(BDC)6], and [Al(OH)(BDC)], respectively (ISO2−: isophthalate, BDC2−: terephthalate). Its use allowed the synthesis of Ce‐UiO‐66 on a gram scale. While CAU‐10 and Ce‐UiO‐66 exhibit properties similar to those reported elsewhere for these two materials, the obtained Al‐MIL‐53 shows no structural flexibility upon adsorption of hydrophilic or hydrophobic guest molecules such as water and xenon and is stabilized in its large‐pore form over a broad temperature range (130–450 K). The stabilization of the large‐pore form of Al‐MIL‐53 was attributed to a high percentage of noncoordinating −COOH groups as determined by solid‐state NMR spectroscopy. The defective material shows an unusually high water uptake of 310 mg g−1 within the range of 0.45 to 0.65 p/p°. In spite of showing no breathing effect upon water adsorption it exhibits distinct mechanical properties. Thus, mercury intrusion porosimetry studies revealed that the solid can be reversibly forced to breathe by applying moderate pressures (≈60 MPa). [ABSTRACT FROM AUTHOR]

Two new zirconium‐based metal–organic frameworks with the composition [Zr6O4(OH)4(OAc)6(BDC)3] (CAU‐26) and [Zr5O4(OH)4(OAc)4(BDC)2] (CAU‐27) are reported, which were synthesized from acetic acid, a rarely utilized but green and sustainable solvent (BDC2−: 1,4‐benzenedicarboxylate). Structure determination aided by automated electron diffraction tomography revealed that CAU‐26 is composed of layers of well‐known {Zr6O8} clusters interconnected by terephthalate ions. In contrast CAU‐27 exhibits a three‐dimensional structure with a so far unknown type of one‐dimensional inorganic building unit (IBU), which can be rationalized as condensed polyhedron‐sharing chains of {Zr6O8} clusters. CAU‐26 occurs as an intermediate of the CAU‐27 synthesis and can be isolated easily, when reaction temperature and time are decreased. We were also able to synthesize two isoreticular derivatives of CAU‐27 with extended linker molecules by implementing 4,4′‐biphenyldicarboxylic acid (H2BPDC) and 5,5′‐dicarboxy‐2,2′‐bipyridine (H2BIPY). All materials show high thermal and chemical stability as well as permanent microporosity. The excellent stability of CAU‐27‐BIPY was exploited to synthesize a performant iridium‐supported heterogeneous MOF‐based catalyst for the direct C−H borylation of arenes. [ABSTRACT FROM AUTHOR]

The bifunctional linker molecule [5‐(phosphonomethyl)‐2,4‐bis(sulfonomethyl)phenyl]methanesulfonic acid (HO3S‐CH2)3‐C6H2‐CH2PO3H2 (abbreviated as H5L4) was employed in systematic high‐throughput investigations in order to discover new coordination polymers (CPs). Employing 27 metal salts of 17 different metals in this investigation, five new compounds [Mg2(HL4)(H2O)6] (1), [Pb4(L4)(OH)3] (2), [Ba2(H2L4)(OH)(H2O)] (3), [Ba2(HL4)(H2O)4] (4), and [Cd2,5(L4)(H2O)7] (5) were discovered and their crystal structures were determined. In all compounds, the sulfonate and phosphonate groups could not be resolved since the P and S atoms are statistically occupying the atom site with a ratio of 0.25 to 0.75. This is reflected in the P–O and S–O bond lengths. Four of the structures were determined from single‐crystal X‐ray diffraction data, whereas the structure of 4 was solved ab initio from powder data using real‐space methods and refined using Rietveld methods. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reactions of three isomeric pyridinedicarboxylic acid linkers – 2,4‐, 2,6‐, and 3,5‐pyridinedicarboxylic acid – with various aluminum salts were investigated by high‐throughput solvothermal synthesis. Two coordination compounds were obtained from the symmetrical linkers (2,6‐ and 3,5‐pyridinedicarboxylic acid). The former is based on molecular Al–O dimers, similar to those reported in the coordination polymer CAU‐16. The latter forms a porous extended framework and is a member of the CAU‐10 family of compounds. Full characterization of both compounds is reported. Crystal structures were determined from high‐resolution synchrotron powder diffraction data. The number of guest water molecules determined crystallographically is in excellent agreement with the number found by thermogravimetric and elemental analyses. It was found that the CAU‐10 analogue undergoes a reversible, displacive phase transition from a non‐centrosymmetric to a centrosymmetric space group on loss of guest water molecules, due to guest‐framework interactions. [ABSTRACT FROM AUTHOR]

The reaction of HfCl4 with fumaric acid (C4H4O4, H2Fum) in a DMF/HCOOH solvent mixture at 120 °C for 24 h results in the formation of a defect‐free sample of Hf‐UiO‐66‐Fum with UiO‐66 structure type. Treatment of the (as)‐synthesized sample in boiling ethanol followed by a thermal treatment at 70 °C leads to a sample of composition [Hf6(μ3‐O)4(μ3‐OH)4(Fum)6]·18H2O·2EtOH. In the crystal structure the hexanuclear clusters {Hf6(μ3‐O)4(μ3‐OH)4} are twelve‐fold connected by C4H2O42– ions to form the framework with the fcu topology. This cluster connectivity was confirmed by a combination of characterization techniques methods, i.e. CHN analyses, N2 sorption as well as 1H‐NMR spectroscopic and thermogravimetric measurements. The MOF shows a thermal stability of T = 390 °C, a specific BET surface area of 389 m2·g–1 and a water uptake of 204 mg·g–1. The crystal structure was determined from powder X‐ray diffraction (PXRD) data, employing the Rietveld method. The compound crystallizes in the cubic space group Pn3 and is isostructural to Zr‐UiO‐66‐Fum. Only a small increase of the lattice parameter a from 17.8309(4) to 17.87978(14) Å is observed. [ABSTRACT FROM AUTHOR]

Single‐crystal electron diffraction has shown to be powerful for structure determination of nano‐ and submicron‐sized crystals that are too small to be studied by single‐crystal X‐ray diffraction. However, it has been very challenging to obtain high quality electron diffraction data from beam sensitive crystals such as metal–organic frameworks (MOFs). It is even more difficult to locate guest species in the pores of MOF crystals. Here, we present synthesis of a novel porous cobalt MOF with 1D channels, [Co2(Ni‐H4TPPP)]⋅2 DABCO⋅6 H2O, (denoted Co‐CAU‐36; DABCO=1,4‐diazabicyclo[2.2.2]octane), and its structure determination using continuous rotation electron diffraction (cRED) data. By combining a fast hybrid electron detector with low sample temperature (96 K), high resolution (0.83–1.00 Å) cRED data could be obtained from eight Co‐CAU‐36 crystals. Independent structure determinations were conducted using each of the eight cRED datasets. We show that all atoms in the MOF framework could be located. More importantly, we demonstrate for the first time that organic molecules in the pores, which were previously difficult to find, could be located using the cRED data. A comparison of eight independent structure determinations using different datasets shows that structural models differ only on average by 0.03(2) Å for the framework atoms and 0.10(6) and 0.16(12) Å for DABCO and water molecules, respectively. Continuous‐rotation electron diffraction (cRED) was used as a stand‐alone method for both structure solution and refinement of submicron‐sized crystals of a novel cobalt metal–organic framework. We show that the method is robust; not only the framework structure, but also solvent molecules in the pores could be precisely located. [ABSTRACT FROM AUTHOR]

The porous metal‐organic framework (MOF) MIL‐160 [Al(OH)(O2C‐C4H2O‐CO2)] was investigated by means of high‐resolution powder X‐ray diffraction experiments using synchrotron radiation. The structures of the dehydrated, hydrated and nitrogen loaded forms of MIL‐160 are refined by the Rietveld method. The structure of the hydrated form, as postulated from solid state NMR and DFT calculations, is confirmed. The host–guest and thermal responses of this compound are also investigated. Adsorption of water is found to induce a phase transition from I41/amd (the dehydrated structure) to I41md (the hydrated structure), mediated by flexibility of the MOF framework. Water molecules were observed to arrange themselves with an ice‐like geometry. Conversely, adsorption of more weakly interacting N2 into the structure or thermal treatment (cooling the sample from 400 to 80 K) leads to no phase transition, indicating that the phase transition is induced by the strong interactions of H2O with the framework. The accuracy of the refined structures is investigated by DFT calculations, which show very small deviations in optimised atomic positions and lattice parameters. [ABSTRACT FROM AUTHOR]

Very few microporous bismuth metal‐organic frameworks have been discovered to date. Of these, no detailed experimental characterization of the synthesis and properties have been reported until now for the only one which can be prepared from inexpensive starting materials: CAU‐17 [Bi(BTC)(H2O)], with H3BTC = trimesic acid. In‐situ powder X‐ray diffraction during solvothermal synthesis of CAU‐17 revealed that it crystallizes rapidly within 2 minutes, and if the reaction is not stopped, the MOF transforms into a nonporous dense purely inorganic material within one hour, revealing that CAU‐17 is a crystalline intermediate phase. Synthesis scale‐up employing more concentrated reaction mixtures resulted in another Bi trimesate of composition [Bi(HBTC)(NO3)(MeOH)]·MeOH, which structurally decomposes upon storage under ambient conditions. Sorption experiments showed that CAU‐17 is microporous with a BET surface area of 530 m2/g. As a potential greenhouse gas sorbent, CAU‐17 showed high SF6/N2 and CO2/N2 selectivity > 31 and 29, respectively. Furthermore, the catalytic activity of CAU‐17 was studied in the regioselective ring‐opening of styrene oxide by methanol to obtain 2‐methoxy‐2‐phenylethanol, thus demonstrating the existence of coordinatively unsaturated sites in the crystal structure of CAU‐17. [ABSTRACT FROM AUTHOR]

Four new coordination polymers (CPs) were obtained under hydrothermal reaction conditions using 2,4,6‐pyridinetricarboxylic acid (H3PTC) and Bi(NO3)3·5H2O. The systematic high‐throughput investigation of the system Bi3+/H3PTC/NaOH/HNO3/H2O led to the compounds [Bi(PTC)(H2O)2] (1), (H3O)[Bi2(PTC)(HPTC)2(H2O)2] (2), α‐[Bi(PTC)] (3) and β‐[Bi(PTC)] (4), which were structurally characterised by single‐crystal X‐ray diffraction. Compounds 1 and 2 crystallise in 2D layered structures, whereas 3 and 4 form 3D coordination networks. Employing the nomenclature proposed by Cheetham et al. 1 and 2 are classified as I1O1 (mixed inorganic–organic layers), 3 as I0O3 (3D coordination polymers) and 4 as I1O2 (mixed inorganic–organic 3D framework). In all cases the nitrogen atom of the linker is coordinated to the Bi3+ ion, which therefore acts as a tridentate pincer‐type ligand. All title compounds were obtained as phase‐pure products employing conventional or microwave‐assisted heating, but the reproducibility of the synthesis depends on reactor size and material. In addition, the luminescence properties of 1 and 2 were studied resulting in a yellow and blue–green luminescence under UV light with emission maxima at 570 nm (λex = 343 nm) and 483 nm (λex = 347 nm) for 1 and 2, respectively. The differences in the spectroscopic properties could be assigned to the distinct coordination and chemical environments of the Bi3+ ions within these compounds. [ABSTRACT FROM AUTHOR]

Abstract: A new aluminium metal‐organic framework (MOF), based on the short aliphatic linker molecule mesaconic acid (H2Mes; methylfumaric acid) is reported. Al‐MIL‐68‐Mes with composition [Al(OH)(O2C‐C3H4‐CO2)]⋅n H2O is obtained after short reaction times of 45 minutes under mild, aqueous synthesis conditions (95 °C). It exhibits a kagome‐like framework structure with large hexagonal, and small trigonal channels (diameters of ≈6 and ≈2 Å, respectively) and a specific surface area of SBET ≈1040 m2 g−1 (VMIC=0.42 cm3 g−1). A sigmoidal vapour sorption isotherm for water, and uptakes of water and methanol above 30 wt. % were observed. Al‐MIL‐68‐Mes is stable against water ad‐/desorption and its thermal stability is 350 °C in air. The proton conductivity for the hydrated MOF showed values up to 1.1×10−5 S cm at 130 °C and 100 % relative humidity, which exceeds the values observed for the non‐hydrated compound by up to four orders of magnitude. Using synchrotron radiation the crystallisation of the MOF by in situ PXRD was also studied at temperatures from 80 to 100 °C. Kinetic evaluation revealed that the induction periods and crystallization times vary depending on the synthesis batch, but the rate limiting steps are consistently observed. [ABSTRACT FROM AUTHOR]

In our contribution to the development of new proton conductive coordination polymers (CPs) we focus on the impact of a partial replacement of Ga3+ by Mg2+. This approach should come along with the introduction of additional protons due to charge balances. In a first step we have synthesized an isostructural compound to the literature known compound AlH3P3N [H6P3N = nitrilotris(methylene)triphosphonic acid], where Al3+ is replaced by Ga3+, since all attempts to incorporate Mg2+ ions directly into AlH3P3N were not successful. The relative amount of Mg2+ and Ga3+ was established by EDX analysis. Rietveld refinement of the synchrotron data located the Ga3+ and Mg2+ ions on a split position, proving the disordered incorporation of the Mg2+ ions. Solid-state NMR spectroscopy confirms a disordered protonation of the phosphonate groups as well and shows that all amine groups are protonated. In order to investigate the effect on the proton conductivity the compounds Ga[H3(O3PCH2)3N], denoted GaH3P3N as well as Ga0.80Mg0.20[H3.20(O3PCH2)3N], denoted GaMgH3.20P3N, were characterized by electrochemical impedance spectroscopy (EIS). Arrhenius behavior in the investigated temperature range (70-130 °C) was found for both compounds (activation energies of Ea = 0.15 eV for GaH3P3N and 0.17 eV for GaMgH3.20P3N). The GaMgH3.20P3N sample shows a reduced proton mobility (σ = 1.2x10-4 S·cm-1) of about one order of magnitude in comparison to GaH3P3N (σ = 1.0x10-3 S·cm-1). [ABSTRACT FROM AUTHOR]

A new rigid metal-organic framework (MOF) with MIL-53 topology built of 2,5-thiophenedicarboxylate (TDC) and Al, Ga, or In is reported. Its structure contains chains of trans corner sharing MO6 octahedra, connected by the linker molecules to form microporous square shaped 1D channels. A combination of powder X-ray diffraction (PXRD), density functional theory (DFT) calculations, and 1H, 13C, and 27Al solid-state NMR spectroscopy (ssNMR) was used to analyse the structures in detail. The synthesis is easily scaled-up using microwave assisted solvothermal conditions. All materials possess a high thermal stability up to 420 °C in air and permanent porosity towards N2, H2, CO2, and CH4. Al-MIL-53-TDC shows a high specific surface area of as,BET = 1150 m2 ·g-1 with a micropore volume of Vmic = 0.48 cm3 ·g-1 as well as water uptake of 5.5H2O molecules per sum formula (469 mg ·g-1) with an a sigmoidal shape, advantageous for heat-transformation processes. Noteworthy, this material adsorbs 2.1 wt % H2 at -196 °C and 1 bar, which surpasses other Al-MIL-53 compounds based on linear functionalized terephthalates. [ABSTRACT FROM AUTHOR]

Biomass-derived lactic acid (LA) is an important platform chemical towards the sustainable production of numerous materials. However, the fermentation process currently in use is limited by the difficult recovery of the LA product from the fermentation broth and results in the generation of stoichiometric amounts of gypsum waste. Herein, we show that metal-organic frameworks (MOFs) of the UiO-66(Zr) type are effective adsorbents for the separation of LA from aqueous (buffer) solutions. These frameworks based on zirconium clusters and terephthalic acid derivatives display a tremendous uptake (up to 42 wt %) and a high affinity for LA. The latter can further be tuned by changing the hydrogen-bonding properties of the functional groups present on the organic ligand. A Rietveld refinement disclosed the specific interaction of LA with the clusters of UiO-66(Zr) and a preferential adsorption on open zirconium sites. Taking advantage of the catalytic activity of UiO-66(Zr), desorption of LA was performed in alcohols to recover up to 73 % as ester. Applied to the recovery of LA, adsorption and reactive desorption offer a direct and gypsum-free strategy as an alternative for the current multi-step process. [ABSTRACT FROM AUTHOR]

The structure of one of the first permanently porous metal phosphonates, MIL-91(Al) was re-determined using high resolution synchrotron powder X-ray diffraction data. The new model is in a lower symmetry space group, with no disordered ligands in the structure, whilst remaining otherwise consistent with the reported compound. New milder synthetic conditions were also developed. [ABSTRACT FROM AUTHOR]

Two new squarate complexes based on aluminum and gallium, [Al2(OH)2(C4O4)2(H2O)4] ·2H2O ( 1) and [Ga2(OH)2(C4O4)2(H2O)4] ·2H2O ( 2) were hydrothermally synthesized and characterized by infrared spectroscopy and thermogravimetric measurements. The structure of 1 was determined by single-crystal X-ray diffraction and the structure of 2 was refined from PXRD data. The dinuclear squarate complexes consist of two MO6 polyhedra ( M = Al or Ga) interconnected by two squarate ions in axial and two hydroxyl groups in equatorial position. Two water molecules are coordinating to each central metal atom in equatorial position to complete the coordination spheres. Furthermore, a non-coordinating water molecule is located between the dinuclear units. Hydrogen bonding leads to the interconnection of the molecular complexes to a three-dimensional network. [ABSTRACT FROM AUTHOR]

Considering the requirements for the commercial production of metal-organic frameworks (MOFs), we investigated the aqueous synthesis of zirconium MOFs. A highly versatile route was identified employing ZrOCl2 ·8H2O, H2O, acetic acid and the respective linker molecule as starting materials. These synthesis conditions are suitable to obtain zirconium MOFs with different topologies like UiO-66-(OH)2, zirconium fumarate, zirconium mesaconate, DUT-67 or MOF-808 with synthesis times of 1 to 5 h under microwave irradiation. The scalability of the synthesis of zirconium fumarate was demonstrated at multigram scale under reflux conditions using conventional dielectric heating. To ease the recovery of this MOF which bypasses filter paper as a pure product, we identified sodium polyacrylate as a suitable additive to induce aggregation of the particles. Moreover, a custom-made prototype flow reactor was developed which allows for the continuous synthesis of zirconium fumarate and UiO-66-NH2 starting from a slurry of the starting materials. The commonly employed toxic organic solvents needed for activation/purification of the MOFs could be successfully replaced by a basic aqueous solution. [ABSTRACT FROM AUTHOR]

An extended series of MIL-53(M)_X metal-organic frameworks (MIL = Materials of Institute Lavoisier; M = Al, Cr, Fe, Sc; X = Cl, CH3, NO2) have been systematically investiaged to explore the impact of the nature of both the metal centre and the functions grafted on to the organic linker on the mechanical behaviour of this family of highly flexible hybrid porous frameworks under the application of an external pressure of up to 3 GPa. The high-pressure X-ray diffraction measurements allowed the characterization of the pressure-induced phase transitions of the hydrated structures, the associated volume changes/pressure transitions, and their mechanical resilience through the determination of their bulk moduli. [ABSTRACT FROM AUTHOR]

The isoreticular analogue of the metal-organic framework UiO-66(Zr), synthesized with the flexible trans-1,4-cyclohexanedicarboxylic acid as linker, shows a peculiar breathing behavior by reversibly losing long-range crystalline order upon evacuation. The underlying flexibility is attributed to a concerted conformational contraction of up to two thirds of the linkers, which breaks the local lattice symmetry. X-ray scattering data are described well by a nanodomain model in which differently oriented tetragonal-type distortions propagate over about 7-10 unit cells. [ABSTRACT FROM AUTHOR]

Only rare earth ions with an effective ionic radius of 92-98 pm lead to the formation of CAU-34. Keywords: Electron diffraction; Metal phosphonate; MOF; Rare earth; Rietveld EN Electron diffraction Metal phosphonate MOF Rare earth Rietveld 1 1 1 12/13/22 20221208 NES 221208 B The Front Cover b shows the diffraction of a focused beam on micro-sized crystallites of Y-CAU-34 located on a carbon grid and the detection of the Rigaku HyPix-ED detector, which is part of a dedicated electron diffractometer. Electron diffraction, Metal phosphonate, MOF, Rare earth, Rietveld. [Extracted from the article]

Ten mixed-linker metal-organic frameworks [Al(OH)( m-BDC-X)1− y( m-BDC-SO3H) y] (H2BDC=1,3-benzenedicarboxylic acid; X=H, NO2, OH) exhibiting the CAU-10-type structure were synthesized. The compounds can be grouped into three series according to the combination of ligands employed. The three series of compounds were obtained by employing different ratios of m-H2BDC-X and m-H2BDC-SO3Li. The resulting compounds, which are denoted CAU-10-H/S x, -N/S x and -O/S x, show exceptionally high thermal stability for sulfonated materials of up to 350 °C. Detailed characterization with special focus on polarity and acidity was performed, and the impact of the additional SO3H groups is clearly demonstrated by changes in the sorption affinities/capacities towards several gases and water vapor. In addition, selected samples were evaluated for proton conductivity and as catalysts for the gas-phase dehydration of ethanol to ethylene. While only very low proton conductivities were observed, a pronounced increase in catalytic activity was achieved. Although reactions were performed at temperatures of 250 and 300 °C for more than 40 h, no desulfonation and no loss of crystallinity were observed, and stable ethanol conversion resulted. This demonstrates the high stability of this material. [ABSTRACT FROM AUTHOR]

The resistance of metal-organic frameworks towards water is a very critical issue concerning their practical use. Recently, it was shown for microporous MOFs that the water stability could be increased by introducing hydrophobic pendant groups. Here, we demonstrate a remarkable stabilisation of the mesoporous MOF Al-MIL-101-NH2 by postsynthetic modification with phenyl isocyanate. In this process 86% of the amino groups were converted into phenylurea units. As a consequence, the long-term stability of Al- MIL-101-URPh in liquid water could be extended beyond a week. In water saturated atmospheres Al-MIL-101-URPh decomposed at least 12-times slower than the unfunctionalised analogue. To study the underlying processes both materials were characterised by Ar, N2 and H2O sorption measurements powder X-ray diffraction, thermogravimetric and chemical analysis as well as solid-state NMR and IR spectroscopy. Postsynthetic modification decreased the BET equivalent surface area from 3363 to 1555 m2g-1 for Al-MIL-101- URPh and reduced the mean diameters of the mesopores by 0.6 nm without degrading the structure significantly and reducing thermal stability. In spite of similar water uptake capacities, the relative humidity-dependent uptake of Al-MIL- 101-URPh is slowed and occurs at higher relative humidity values. In combination with 1H-27Al D-HMQC NMR spectroscopy experiments this favours a shielding mechanism of the Al clusters by the pendant phenyl groups and rules out pore blocking. [ABSTRACT FROM AUTHOR]

The local, deterministic optimisation algorithm BOBYQA (bound optimisation by quadratic approximation) was applied for the computer-assisted optimisation of inorganic-organic hybrid compounds. Four proof-of-concept studies were performed: 1) increasing the crystallinity and 2) inhibiting the crystallisation of [Ca(H2O)2(H2PMBC)2] (H2PMBC−=−HO3P-CH2-C4H6-COOH), 3) increasing the crystal size of [Bi(H2O)(BTC)] (BTC3−=benzene-1,3,5-tricarboxylate) and 4) tuning the particle sizes of [Al(OH)(CDC)]⋅ x H2O (CDC2−= trans-1,4-cyclohexane dicarboxylate) to a desired value. The measurable quantities of crystallinity, crystal size and hydrodynamic diameter were used as the quality criteria for the optimisation, and the parameters of reaction time and temperature, molar ratios and overall concentration of the starting materials as well as the stirring rate were varied. The crystallinity of [Ca(H2O)2(H2PMBC)2] was increased in three optimisation steps by approximately 14 %, which was accompanied by an increase in crystal size by a factor of approximately 40. These crystals were suitable for structure determination from single-crystal X-ray diffraction data. The crystallisation of the same compound could be completely inhibited and clear solutions were obtained. The average crystal size of [Bi(H2O)(BTC)] was increased from (22.2±4.5) to (34.8±9.5) μm and the upper limit increased from 30.0 to 57.7 μm over the course of the optimisation. For the application in Bragg stacks, the variation of particle sizes of [Al(OH)(CDC)]⋅ x H2O was studied. Although we aimed at a decrease to 100 nm, a lower limit of 460 nm and polydispersity index of 0.03 were accomplished. The convergence of the algorithm indicates that the optimisation progress is close to completion and the found value for the particle size is close to the lower limit in the system of the chosen parameters. These proofs-of-concept studies demonstrate the potential of optimisation algorithms like BOBYQA in synthesis optimisation experiments. At the same time, the convergence behaviour of the algorithm gives an indication of the progress of an optimisation. [ABSTRACT FROM AUTHOR]

The new aminomethylphosphonic acid H2O3P-CH2-NC5H10N-CH2-PO3H2 (H4 L2) was synthesized and characterized in detail. Its reaction with Cu(NO3)2 ·3H2O under hydrothermal conditions led to the formation of the copper phosphonate [Cu(H2 L2)], which was structurally characterized by single-crystal X-ray diffraction [space group P21/ n, a = 8.4754(17), b = 16.903(3), c = 9.0787(18) Å, β = 106.58(3)°, R1 = 0.0296, wR2 = 0.0728]. In the crystal structure each Cu2+-ion is chelated by one ligand molecule forming tetragonal planar CuO2N2 polyhedra. Coordination by an oxygen atom from an adjacent second ligand molecule leads to [Cu(H2 L2)]2 dimers, which contain tetragonal pyramidal CuO3N2 polyhedra. These dimers are linked by hydrogen bonds to one-dimensional chains, which are further connected by van der Waals interactions. The compound was further characterized by powder X-ray diffraction (PXRD), elemental analysis, IR spectroscopy, Raman spectroscopy, and magnetic measurements. [ABSTRACT FROM AUTHOR]