Flexible metal-organic frameworks (MOFs) can undergo fascinating structural transitions triggered by external stimuli, such as adsorption/desorption of specific guest molecules or temperature ...changes. In this detailed study we investigate the potentials and limitations of tuning framework flexibility systematically by exploiting the powerful concept of mixed-linker solid solutions. We chose the prototypical family of functionalized pillared-layer MOFs of the general type Zn2(fu(1)-bdc)2x(fu(2)-bdc)(2-2x)dabco (with x = 1.00, 0.75, 0.50, 0.25 and 0.00; fu-bdc = 2,5-dialkoxy-1,4-benzenedicarboxylate with varying alkoxy chain length, dabco = 1,4-diazabicyclo2.2.2octane) and examined their guest responsive, as well as intrinsic temperature dependent structural flexibility by X-ray diffraction, gas physisorption and calorimetric measurements. The ratio of the different fu-bdc linkers can be adjusted freely, offering opportunity for a targeted design of these functional materials by modulating their key features, such as magnitude of framework contraction upon guest removal, breathing behaviour upon CO2 adsorption/desorption, thermoresponsive phase behaviour, and their general thermal expansivity, by the careful choice of fu-bdc linkers and their combination.
In this article, the specification and application of the new double‐sided YAG laser‐heating system built on beamline I15 at Diamond Light Source are presented. This system, combined with diamond ...anvil cell and X‐ray diffraction techniques, allows in situ and ex situ characterization of material properties at extremes of pressure and temperature. In order to demonstrate the reliability and stability of this experimental setup over a wide range of pressure and temperature, a case study was performed and the phase diagram of lead was investigated up to 80 GPa and 3300 K. The obtained results agree with previously published experimental and theoretical data, underlining the quality and reliability of the installed setup.
A double‐sided, off‐axis laser‐heating system for monochromatic X‐ray diffraction experiments using a diamond anvil cell has been installed at beamline I15 at Diamond Light Source. Measurements of the pressure–temperature phase diagram of Pb demonstrate the reliability of the setup and the high quality of the data.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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.
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Double metal cyanides (DMCs) are well known, industrially applied catalysts for ring opening polymerization reactions. In recent years, they have been studied for a variety of catalytic reactions, as ...well as other applications, such as energy storage and Cs sorption. Herein, a new, layered DMC phase (L-DMC), Zn2Co(CN)6(CH3COO)·4H2O, was synthesized. The structure, which crystallizes in the monoclinic space group P21/m, consists of positively charged {Zn2Co(CN)6}+ DMC layers linked through acetate groups and presents a new layered structure to the family of double metal cyanides. L-DMC proved to be a reusable and stable catalyst that exhibited a higher activity than the benchmark DMC catalyst in two important applications: hydroamination of phenylacetylene with 4-isopropylaniline and polymerization of 1,2-epoxyhexane.
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This work presents the fabrication of 3D‐printed composite objects based on copper(II) 1D coordination polymer (CP1) decorated with thymine along its chains with potential utility as an environmental ...humidity sensor and as a water sensor in organic solvents. This new composite object has a remarkable sensitivity, ranging from 0.3% to 4% of water in organic solvents. The sensing capacity is related to the structural transformation due to the loss of water molecules that CP1 undergoes with temperature or by solvent molecules' competition, which induces significant change in color simultaneously. The CP1 and 3D printed materials are stable in air over 1 year and also at biological pHs (5–7), therefore suggesting potential applications as robust colorimetric sensors. These results open the door to generate a family of new 3D printed materials based on the integration of multifunctional coordination polymers with organic polymers.
This work opens the door to the generation of new 3D‐printed materials based on the integration of multifunctional coordination polymers with organic polymers. The fabrication of 3D‐printed composite objects based on Cu(II) coordination polymer, with utility as a water colorimetric sensor, is presented. The sensing capacity is related to the loss of water molecules with temperature or by the solvent molecules' competition.
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Self‐assembly of iron oxide nanoparticles (IONPs) into 1D chains is appealing, because of their biocompatibility and higher mobility compared to 2D/3D assemblies while traversing the circulatory ...passages and blood vessels for in vivo biomedical applications. In this work, parameters such as size, concentration, composition, and magnetic field, responsible for chain formation of IONPs in a dispersion as opposed to spatially confining substrates, are examined. In particular, the monodisperse 27 nm IONPs synthesized by an extended LaMer mechanism are shown to form chains at 4 mT, which are lengthened with applied field reaching 270 nm at 2.2 T. The chain lengths are completely reversible in field. Using a combination of scattering methods and reverse Monte Carlo simulations the formation of chains is directly visualized. The visualization of real‐space IONPs assemblies formed in dispersions presents a novel tool for biomedical researchers. This allows for rapid exploration of the behavior of IONPs in solution in a broad parameter space and unambiguous extraction of the parameters of the equilibrium structures. Additionally, it can be extended to study novel assemblies formed by more complex geometries of IONPs.
Biocompatible iron oxide nanoparticles in dispersion can be controlled to form flexible and reversible chains in the presence of a magnetic field, which is useful for biomedical applications. The role of control parameters is determined and these novel assemblies formed in dispersions are visualized using advanced scattering methods and reverse Monte Carlo simulations.
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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.
Camouflaged from diffraction: The aliphatic isoreticular analogue of the well‐known MOF UiO‐66(Zr) undergoes a unique and reversible phase change upon guest removal. This change involves a topology‐dictated loss of long‐range order through the correlated formation of short‐range ordered nanodomains.
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The mechanical properties of calcium fumarate trihydrate, a 1D coordination polymer considered for use as a calcium source for food and beverage enrichment, have been determined via nanoindentation ...and high-pressure X-ray diffraction with single crystals. The nanoindentation studies reveal that the elastic modulus (16.7–33.4 GPa, depending on crystallographic orientation), hardness (1.05–1.36 GPa), yield stress (0.70–0.90 GPa), and creep behavior (0.8–5.8 nm/s) can be rationalized in view of the anisotropic crystal structure; factors include the directionality of the inorganic Ca–O–Ca chain and hydrogen bonding, as well as the orientation of the fumarate ligands. High-pressure single-crystal X-ray diffraction studies show a bulk modulus of ∼20 GPa, which is indicative of elastic recovery intermediate between small molecule drug crystals and inorganic pharmaceutical ingredients. The combined use of nanoindentation and high-pressure X-ray diffraction techniques provides a complementary experimental approach for probing the critical mechanical properties related to tableting of these dietary supplements.
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Systematic investigation of the reactions of the system AlCl3·6H2O/pyridine-2,4,6-tricarboxylic acid (H3 PTC)/pyridine in water yielded two new compounds, both containing the dimeric ...{AlPTC(μ-OH)(H2O)}2 2– unit. With long reaction times, the framework compound Al(μ-OH){AlPTC(μ-OH)(H2O)}2·2H2O (CAU-16, compound 1) is obtained, the first example of a framework compound with a metal–organic cluster linker, and bearing the MIL-53 network. Although the compound does not breathe, as other MIL-53 compounds do, it has a maximum uptake of CO2 of 1.76(2) mmol g–1 at 196 K. With shorter reaction times, the molecular compound {Al(HPTC)(μ-OH)(H2O)}2 (2) was prepared, leading to the proposal of a crystallization scheme for the Al3+-pyridine-2,4,6,-tricarboxylic acid system. To determine whether further framework compounds bearing hybrid metal cluster linkers could be prepared, systematic high-throughput investigations of pyridine-2,4,6-tricarboxylic acid in water with Ga3+ and In3+ were undertaken. These yielded two chain-type compounds, GaPTC(H2O)2 (3) and InPTC(H2O)2 (4), with different coordination chemistries. Optimized syntheses for compounds 1, 2, and 4 are reported.
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