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Considering the discharge of radioactive and non-radioactive effluents during the mining process, we report on a study that proposes to use optical sensing for the detection and monitoring of pollutants. This is realized by doping of Tb3+ ions in a metal–organic framework, namely UiO-66-(COOH)2, and taking advantage of the host–guest interactions which allow analyte molecules to be pre-concentrated within the pores of the material, thus influencing the light absorption and emission profile of Tb3+ ions. Concentration-dependent spectroscopy analysis shows that Tb@UiO-66-(COOH)2 has a luminescence turn-off behaviour which is more sensitive in the presence of Ni2+ and UO22+ ions as compared with monovalent (Ag+), bivalent (Co2+), trivalent (Fe3+), and tetravalent (Sn4+) cations. The relative luminescent intensity (I0/I) as a function of the concentrations of both Ni2+ and UO22+ shows a linear response in a broad concentration range (10−7–10−3 M). The limit of detection (LOD) for Ni2+ is 5.7 μg L−1, which is lower than the allowable concentration limit (0.02 mg L−1) defined by the national environmental quality standard of surface water GB 3838. The LOD for UO22+ is 0.02 μg L−1, far below the World Health Organization maximum standards for potable water (30 μg L−1). Therefore, Tb@UiO-66-(COOH)2 enables the detection of these ions with high sensitivity. Notably, the optical response measured at low concentrations of Ni2+ and UO22+ is not affected even in the presence of interfering metallic ions. These results demonstrate for the first time that Tb@UiO-66-(COOH)2 is a versatile multi-hazard sensor for the detection of non-radioactive and radioactive elements. It also opens opportunities for the selective adsorption and extraction of UO22+ due to the high-stability functionality of Tb@UiO-66-(COOH)2.

UiO-66 is a benchmark metal-organic framework that holds great promise for the design of new functional materials. In this work, we perform two-dimensional infrared measurements on polycrystalline membranes of UiO-66 grown on c-sapphire substrates. We study the symmetric and antisymmetric stretch vibrations of the carboxylate groups of the terephthalate linker ions and find that these vibrations show a rapid energy exchange and a collective vibrational relaxation with a time constant of 1.3 ps. We also find that the symmetric vibration of the carboxylate group is strongly coupled to a vibration of the aromatic ring of the terephthalate ion. We observe that the antisymmetric carboxylate vibrations of different terephthalate linkers show rapid resonant (Förster) energy transfer with a time constant of ∼1 ps.

The synthesis of chiral metal–organic frameworks (MOFs) is highly relevant for asymmetric heterogenous catalysis, yet very challenging. Chiral MOFs with MOF‐74 topology were synthesised by using post‐synthetic modification with proline. Vibrational circular dichroism studies demonstrate that proline is the source of chirality. The solvents used in the synthesis play a key role in tuning the loading of proline and its interaction with the MOF‐74 framework. In N,N′‐dimethylformamide, proline coordinates monodentate to the Zn2+ ions within the MOF‐74 framework, whereas it is only weakly bound to the framework when using methanol as solvent. Introducing chirality within the MOF‐74 framework also leads to the formation of defects, with both the organic linker and metal ions missing from the framework. The formation of defects combined with the coordination of DMF and proline within the framework leads to a pore blocking effect. This is confirmed by adsorption studies and testing of the chiral MOFs in the asymmetric aldol reaction between acetone and para‐nitrobenzaldehyde., Chemistry - A European Journal, 26 (61), ISSN:0947-6539, ISSN:1521-3765

Monitoring CO2 levels in the atmosphere as well as in work place environments is strictly regulated. Commercial sensors based on polymeric materials have low operating temperature, yet exhibit low selectivity. Molecular systems such as metal-organic frameworks (MOFs) are promising materials that can be used for CO2 sensing applications. They are formed through strong interactions between metal ions or clusters with easy-to-modify organic linkers and have exceptionally high surface areas and well-defined accessible pores. The host-guest interactions in MOFs and their responsiveness to physical and chemical stimuli can be exploited to address the critical issues in chemical sensing applications, such as fast response, sensitivity and specificity. This review provides an overview of the techniques that can be used to detect CO2 through the use of MOFs, highlighting the most promising MOF materials that exhibit CO2 sensing properties. The potential of MOFs in the development of CO2 sensors is also discussed.

Chiral induction is a simple and inexpensive approach to synthesise chiral metal–organic frameworks, even when using achiral building-blocks. The challenge lies in selecting the proper chiral inductor. This can only be achieved upon understanding the mechanism behind the chirality transfer from the chiral guest to the achiral MOF. In this work, the role of two types of chiral additives and different solvents was investigated in the crystallization of isoreticular MOF-74. We show that pyrrolidone-based solvents can interact with the framework walls and influence the thermal stability of the MOF. The role of the different chiral additives is related to the strength of their interaction with the MOF. Unlike cinchona alkaloids that have weak interactions with the framework, l- or d-trans-4-hydroxyproline (l- or d-Hyp) can strongly bind to the Zn2+ metal centres and cause the twisting of the organic linker. Moreover, l- and d-Hyp additives can affect the IRMOF-74 nucleation process depending on their concentration and handedness., Strongly interacting chiral additives play a complex role during the crystallisation of chiral isoreticular MOF-74. They can coordinate to the open sites of the metal ions and induce strain on the framework, leading to a local twisting of the organic linker.

This study presents a straightforward approach for the in situ polymerization of poly(N-isopropylacrylamide) (PNIPAM) chains within the one-dimensional (1D) pores of the five-coordinated zinc-based metal–organic framework DMOF in order to obtain new MOF-based composites. The loading amount of PNIPAM within DMOF ⊃ PNIPAM composites can be tuned by changing the initial weight ratio between NIPAM, which is the monomer of PNIPAM, and DMOF. The guest PNIPAM chains in the composites block partially the 1D pores of DMOF, thus leading to a narrowed nanospace. The water adsorption studies reveal that the water uptake increased by increasing the loading of PNIPAM in the final DMOF ⊃ PNIPAM composites, indicating that the exposed amide groups of PNIPAM gradually alter the hydrophobicity of pristine DMOF and lead to hydrophilic DMOF ⊃ PNIPAM composites. The composite with the highest loading of PNIPAM displays a selective adsorption for water and methanol over ethanol when using equimolar mixtures of methanol–ethanol and water–ethanol. This is confirmed by the single-component adsorption measurements as well as ideal adsorbed solution theory molecular simulations. Additionally, the water stability of pristine DMOF has been greatly improved after the incorporation of PNIPAM in its pores. PNIPAM can undergo a phase transition between hydrophobic and hydrophilic phases in response to a low temperature change. This property is used in order to control the desorption of water and methanol molecules, thus enabling an efficient and cost-effective regeneration process.

A multiluminescent composite material, CDs@EuW–MOF, is synthesized by self‐assembling molecular building‐blocks in the presence of carbon dots (CDs). Using water soluble CDs within the growth media of a hydrophilic metal‐organic framework (MOF) enables the incorporation of the CDs within MOF pores through a one‐pot synthesis. The emission spectra obtained using a broad range of excitation wavelengths (295–400 nm) show multiple emissions including the Eu3+ red emission and the dual‐color (blue and green) emissions of the CDs. The red emission intensity of Eu3+ ions decreases in the presence of water molecules, leading to the ratiometric detection of water in methanol within a wide response range of 0–30 % (V/V). Due to the quenching effect on the CDs emission, this composite can also sense acetonitrile. The results demonstrate that using a molecular building‐block approach is an efficient route towards the design of multiluminescent functional materials.

This work reports a new approach for the synthesis of a zeolitic imidazolate framework (ZIF-8) composite. It employs the direct growth of the crystalline ZIF-8 on a mixed-metal oxide support TiO2 -SiO2(TSO), which mimics the porous structure of Populus nigra. Using the natural leaf as a template, the TSO support was prepared using a sol-gel method. The growth of the ZIF-8 layer on the TSO support was carried out by the seeds and second growth method. This method facilitates the homogeneous dispersion of ZIF-8 crystals at the surface of the TSO composite. The ZIF-8@TSO composite adsorbs methanol selectively, mainly due to the hierarchical porous structure of the mixed oxide support. As compared with the as-synthesized ZIF-8, a 50% methanol uptake is achieved in the ZIF-8@TSO composite, with only 25 wt % ZIF-8 loading. LAST simulations show that the ZIF-8@TSO composite has a preferential adsorption toward methanol when using an equimolar methanol-ethanol mixture. An opposite behavior is observed for the as-synthesized ZIF-8. The results show that combining MOFs and mixed-oxide supports with bioinspired structures opens opportunities for synthesizing new materials with unique and enhanced adsorption and separation properties.

Determining accurately CO2 levels is highly relevant when monitoring indoor air quality. Nondispersive infrared (NDIR) sensors are the most often used sensors for measuring carbon dioxide concentration. However, the complexity of the device, power consumption and scalability are the main drawbacks associated with the state-of-the-art devices. In this work, we discuss the application of metal–organic frameworks for sensing of CO2 molecules using electrochemical impedance spectroscopy. Impedance CO2 sensors were fabricated using two metal–organic frameworks known for their selective CO2 adsorption capability as well as their high proton conductivity, namely Zn-MOF-74 and NdMo-MOF. Both sensors showed a significant change in impedance when changing the CO2 concentration and the relative humidity. Notably, the Zn-MOF-74 impedance sensor showed fast response when changing the humidity and CO2 concentration.

This review gives an overview of the synthetic strategies used for designing metal-organic frameworks (MOFs) and MOFs-based composites studied for water-alcohol separation applications. It shows that various organic linkers, including flexible, hydrophobic and zwitterionic ligands have been used for the synthesis of MOFs with flexible frameworks, highly hydrophobic MOFs as well as MOFs with unique electronic distribution in the pores. Due to their specific structural properties, all these materials show different adsorption behavior in the presence of water and alcohols, being able to separate water-alcohol mixtures. Several studies focused on using microporous MOFs to separate water-alcohol mixtures based on the difference in the molecular size of water and alcohols. Combining MOFs with organic polymers into composites is viewed as a viable alternative to tackle some problems that powdered MOFs may cause in industrial applications. The research so far shows that MOFs embedded in polymer matrixes have led to improved efficiency and mixture permeability when comparing with the performance of pristine polymer membranes. Nevertheless, the design of membranes with high permeability, selectivity and stability is difficult due to the swelling of the polymer matrix as well as the difficulties in retaining the matrix integrity while increasing the MOF loading.

A new series of alkaline-earth-metal based coordination polymers were synthesized by using a pyrazine-2,5-dicarboxylic acid (2,5-H2pzdc) ligand under hydrothermal conditions. These compounds show a variety of structural topologies, reflecting the variable coordination geometries of the alkaline-earth ions as well as the key role of the metal precursor salts. Ca, Sr, and Ba give porous three-dimensional compounds, namely [Ca(2,5-pzdc)(H2O)2]·H2O (1), [Sr(2,5-pzdc)(H2O)4]·H2O (3), [Ba(2,5-pzdc)(H2O)4]·2H2O (4) and [Ba(2,5pzdc)(H2O)2] (5), that feature one-dimensional hydrophilic channels which are filled with water molecules. The Sr compound retains its structure when the lattice water molecules are removed, while the other compounds undergo a structural rearrangement. The hydrophilicity of the Sr compound combined with its high stability even in the absence of guest molecules are the key characteristics that determine its good water adsorption and proton conductivity properties

Petrochemical refineries must separate hydrocarbon mixtures on a large scale for the production of fuels and chemicals. Typically, these hydrocarbons are separated by distillation, which is extremely energy intensive. This high energy cost can be mitigated by developing materials that can enable efficient adsorptive separation. In this critical review, the principles of adsorptive separation are outlined, and then the case for C4 separations by using zeolites and metal-organic frameworks (MOFs) is examined. By analyzing both experimental and theoretical studies, the challenges and opportunities in C4 separation are outlined, with a focus on the separation mechanisms and structure-selectivity correlations. Zeolites are commonly used as adsorbents and, in some cases, can separate C4 mixtures well. The pore sizes of eight-membered-ring zeolites, for example, are in the order of the kinetic diameters of C4 isomers. Although zeolites have the advantage of a rigid and highly stable structure, this is often difficult to functionalize. MOFs are attractive candidates for hydrocarbon separation because their pores can be tailored to optimize the adsorbate-adsorbent interactions. MOF-5 and ZIF-7 show promising results in separating all C4 isomers, but breakthrough experiments under industrial conditions are needed to confirm these results. Moreover, the flexibility of the MOF structures could hamper their application under industrial conditions. Adsorptive separation is a promising viable alternative and it is likely to play an increasingly important role in tomorrow's refineries.

Tendons and ligaments injuries have become more and more common due to the increase of the general populations interest in sports and physical activities. Beginning with the 1970s many researchers have tried to reconstruct the torn ligaments and tendons, at first using products such as Polyflex and Proplast ligaments, with poor results. In recent years the use LARS ligament has been researched. The Ligament Augmentation and Reconstruction System, now at its 3rd generation, is an artificial ligament made out of polyethylene terephthalate (PET) that over time allows tissue ingrowth, recreating the natural orientation of anatomical ligament and tendon fibers.

The lack of meniscal tissue increases the risk of early cartilage degeneration. Classic treatment includes suturing and partial menscectomies, total meniscectomies being abandoned. Modern treatments are based on the implantation of special scaffolds that replace some of the lost meniscal tissue. This paper reviews the basic principles of modern treatment of the menisci and it includes a retrospective study, in which a total of 10 patients (7 men and 3 women, mean age: 28.28 (21-38)) were enrolled. All patients had previous surgery and were subjected to arthroscopic treatment with a biodegradable scaffold (Actifit®). They received KOOS (Knee Injury and Ostheoarthritis Outcome Score), Lysholm and Tegner score. The Tegner score was not very useful in determining the success or failure of the surgery. The Lysholm and KOOS score results improved at the 1-year follow-up. The results of the scores that the patients filled out, showed an improvement in their preoperatively knee related problems. The Actifit® scaffold is safe and effective in treating meniscal defects.

Combined photoluminescence and impedance spectroscopy studies show that a europium-based metal–organic framework behaves as a highly effective and reliable humidity sensor, enabling dual-mode humidity detection.

Stefania Tanase and Anastasios J. Tasiopoulos introduce the Molecular Systems Design & Engineering themed collection on molecular systems for sensing.

Acidic γ-Al2O3 is an active catalyst for the dehydration of methanol to dimethyl ether (DME). However, the produced steam reduces the activity. In this work, the influence of the exposure of γ-Al2O3 to steam on the catalytic activity for methanol dehydration has been determined. At 250 °C and increasing stream partial pressure the conversion of γ-Al2O3 into γ-AlO(OH) is observed at a p(H2O) of 13–14 bar. As a consequence, the catalytic activity decreases, reducing the rate of methanol dehydration to around 25%. However, this conversion is reversible and under reaction conditions γ-AlO(OH) converts back to γ-Al2O3, recovering its catalytic activity.

Supramolecular isomerism of metal-organic frameworks (MOFs) is known for several MOF structures, having direct implications on the properties of these materials. Although the synthesis of MOF isomers is mainly serendipitous in nature, achieving controlled formation of a target framework is highly relevant for practical applications. This work discusses the influence of additives and synthesis conditions on the formation of porous isomers containing Zn2+ as nodes and 2,5-dihydroxy-1,4-benzenedicarboxylate (dobdc4-) as a linker. Using solvent mixtures containing strongly coordinated molecules, e.g. N,N'-dimethylformamide (DMF) and N-methylpyrrolidone (NMP), facilitates the formation of porous structures of type [Zn2(dobdc)(S)x]·yS (S = DMF, NMP) which are built from dinuclear Zn2(O)2(CO2)3 secondary building units (SBUs) consisting of two different edge-sharing polyhedra with the Zn2+ ions in a unsaturated coordinative environment. In the presence of water, the Zn2+ dimers are converted to one-dimensional infinite Zn2+ chains, in which the number of Zn2+-linker bonds increases, therefore giving a hydrolytically more stable coordination environment. The full characterization of the isomers as well as their conversion to the most stable isomer is presented., This work is part of the Research Priority Area Sustainable Chemistry of the University of Amsterdam, http://suschem.uva.nl, and was funded by a TOP-PUNT grant from the NWO. It was also supported by Spanish MINECO (projects PN RTI2018-095622-B-I00), the Catalan AGAUR (project 2014 SGR 80), the ERC under the EU-FP7 (ERC-Co 615954), and the CERCA Program/Generalitat de Catalunya. ICN2 was supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706).

Correction for ‘Role of additives and solvents in the synthesis of chiral isoreticular MOF-74 topologies’ by Andreea Gheorghe et al., Dalton Trans., 2021, DOI: 10.1039/D1DT01945G.

A new series of cyanide-bridged assemblies, {KH[Ln2(2,3-pzdc)2(CH3OH)(H2O)7][M(CN)8]}·5H2O (Ln3+ = Nd, Gd, Tb, and Dy; M4+ = Mo and W), were synthesised by self-assembling lanthanide ions and octacyanometallate ions in the presence of pyrazine-2,3-dicarboxylic acid (2,3-H2pzdc). These compounds have a 3D structure in which octagon-like Ln4M4(CN)8 rings are connected through a second Ln3+ center via the carboxylate groups of one 2,3-pzdc. The resulting 1D channels are filled with K+ ions and lattice water molecules. The temperature and field dependent magnetization studies as well as ab initio calculations indicate weak ferromagnetic interactions between the Gd3+ ions within the GdMo compound whilst no magnetic interactions exist in GdW analogues. The magnetic properties of Nd3+, Tb3+ and Dy3+ compounds are strongly dominated by the magnetic anisotropy of the lanthanide ions, irrespective of the octacyanometallate building-block used.

Homochiral metal–organic frameworks (HMOFs) are attractive materials for asymmetric catalysis because they possess high surface area and uniform active sites. A variety of catalytic applications reported so far indicate that HMOFs catalyse a range of transformations, including cyanosilylation, aldol condensation and hydrogenation reactions. Besides contribution to fundamental knowledge, it is also important to evaluate the relevance of organic transformations catalysed by HMOFs and how existing achievements compare with already established enantioselective catalysts. This mini-review gives an overview of the structural design and the catalytic performance of HMOFs and it focuses on the relevance of the chemical reactions tested. It aims at combining the existing demand for heterogeneous asymmetric catalysts with the current knowledge on HMOFs. This is important for the MOF community since it highlights relevant broad scope asymmetric catalytic transformations performed in industry and the insight gained from the catalytic reactions carried out using HMOFs as catalysts. We hope that this work will motivate researchers to rationally design HMOFs with a goal to unveil reaction mechanisms and the interactions between the HMOFs and the reaction molecules for industrially relevant catalytic reactions.

We investigate and discuss the proton conductivity properties of the cyanide-bridged metal–organic framework (MOF) [Nd(mpca)2Nd(H2O)6Mo(CN)8]·nH2O (where mpca is 5-methyl-2-pyrazinecarboxylate). This MOF is one of an exciting class of cyanide-bridged materials that can combine porosity with magnetism, luminescence, and proton conductivity. Specifically, we show that this material features highly hydrophilic open channels filled with water molecules. They enable a high proton conductivity, as much as 10−3 S cm−1. A rich hydrogen-bonding network, formed by the ligands' carboxylate groups with both coordinated and lattice water molecules, facilitates this high proton conductivity. Combined thermogravimetric studies, FTIR spectroscopy and PXRD analysis show that upon heating at 80 °C, the lattice water molecules are removed without any change in the framework. Further heating at 130 °C results in a partial removal of the coordinated water molecules, while still retaining the original framework. These activated MOFs shows an increasing conductivity from ∼10−9 S cm−1 to ∼10−3 S cm−1 when the relative humidity increases from 0% to 98%. Our studies show that the increase in proton conductivity is correlated with the re-hydration of the framework with lattice water molecules. The Arrhenius activation energy for the proton conductivity process is low (Ea = 37 kJ mol−1), indicating that the protons “hop” through the channels following the Grotthuss mechanism. The fact that this MOF is remarkably stable both under high humidity conditions and at relatively high temperatures (up to 130 °C) makes it a good candidate for real-life applications.

We present a simple method for solubilising lignin using liquid ammonia. Unlike water, which requires harsh conditions, ammonia can solubilise technical lignins, in particular kraft lignin. A commercial pine wood Kraft lignin (Indulin AT) was solubilized instantaneously at room temperature and 7–11 bars autogeneous pressure, while a commercial mixed wheat straw/Sarkanda grass soda lignin (Protobind™ 1000) was solubilized within 3 h at ambient temperature, and 30 min at. 85 °C. Hydroxide salts were not required. Wheat straw, poplar and spruce organosolv lignins, as well as elephant grass native lignin (MWL) were also solubilized, albeit at lower values. Different sequences of solubilisation and extraction were tested on the Protobind™ 1000 lignin. The remaining lignin residues were characterized by FTIR, size exclusion chromatography (SEC), elemental analysis (ICP), 2D-NMR and 31P NMR. Liquid ammonia is not an innocent solvent, as some nitrogen was incorporated in the residual lignin which then rearranged to higher molecular weight fractions. Nevertheless, the mild solubilisation conditions make liquid ammonia an attractive candidate as a solvent for lignin in future biorefinery processes.

Light upconversion by triplet-triplet annihilation (TTA-UC) in nanoparticles has received considerable attention for bioimaging and light activation of prodrugs. However, the mechanism of TTA-UC is inherently sensitive for quenching by molecular oxygen. A potential oxygen protection strategy is the coating of TTA-UC nanoparticles with a layer of oxygen-impermeable material. In this work, we explore if (organo)silica can fulfill this protecting role. Three synthesis routes are described for preparing water-dispersible (organo)silica-coated red-to-blue upconverting liposomes. Their upconversion properties are investigated in solution and in A549 lung carcinoma cells. Although it was found that the silica offered no protection from oxygen in solution and after uptake in A549 cancer cells, upon drying of the silica-coated liposome dispersion in an excess of (organo)silica precursor, interesting liposome-silica nanocomposite materials were obtained that were capable of generating blue light upon red light excitation in air.

We present a new metal-organic framework (MOF) built from lanthanum and pyrazine-2,5-dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)(1.5)(H2O)(2)]center dot 2H(2)O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration cycles. Unusually for a MOF, it also features a high hydrothermal stability. This makes it an ideal candidate for air drying as well as for separating water/alcohol mixtures. The ability of the activated MOF to adsorb water selectively was evaluated by means of thermogravimetric analysis, powder and single-crystal X-ray diffraction and adsorption studies, indicating a maximum uptake of 1.2 mmol g(-1) MOF. These results are in agreement with the microporous structure, which permits only water molecules to enter the channels (alcohols, including methanol, are simply too large). Transient breakthrough simulations using water/methanol mixtures confirm that such mixtures can be separated cleanly using this new MOF.

Metal-organic frameworks (MOFs) form a new class of materials with well-defined yet tunable properties. These are crystalline, highly porous and exhibit strong metal-ligand interactions. Importantly, their physical and chemical properties, including pore size, pore structure, acidity, and magnetic and optical characteristics, can be tailored by choosing the appropriate ligands and metal precursors. Here we review the key aspects of synthesis and characterization of MOFs, focusing on lanthanide-based and vanadium-based materials. We also outline some of their applications in catalysis and materials science.

This short critical review outlines possible scenarios for using lignin as a feedstock in a biorefinery environment. We first explain the position of biomass with respect to fossil carbon sources and the possibilities of substituting these in tomorrow's transportation fuels, energy, and chemicals sectors. Of these, the conversion of biomass to chemicals is, in our opinion, the most worthy. Focusing on lignin, we describe the four main processes for its industrial separation (the Sulfite, Soda, Kraft, and Organosolv processes). Then, we detail several short- and long-term perspectives for its valorisation to aromatics, polymers and materials, as well as new products and in-the-pipeline processes. Finally, we examine the limitations in current lignin valorisation and suggest possible ways forward. Combining the chemical aspects with up-to-date data from economic analyses gives a pragmatic and realistic overview of the commercial applications and possibilities for lignin in the coming decades, where biomass will join shale gas and crude oil as a valid and economical carbon source.

The fabrication of nanoporous poly(vinylidene fluoride) (PVDF) and PVDF/nickel nanocomposites from semicrystalline block copolymer precursors is reported. Polystyrene-block-poly(vinylidene fluoride)-block-polystyrene (PS-b-PVDF-b-PS) is prepared through functional benzoyl peroxide initiated polymerization of VDF, followed by atom transfer radical polymerization (ATRP) of styrene. The crystallization of PVDF plays a dominant role in the formation of the block copolymer structure, resulting in a spherulitic superstructure with an internal crystalline-amorphous lamellar nanostructure. The block copolymer promotes the formation of the ferroelectric beta-polymorph of PVDF. Selective etching of the amorphous regions with nitric acid leads to nanoporous PVDF, which functions as a template for the generation of PVDF/Ni nanocomposites. The lamellar nanostructure and the beta-crystalline phase are conserved during the etching procedure and electroless nickel deposition.

This short critical review outlines the main synthetic strategies used in the designed synthesis of lanthanide-based metal organic frameworks (Ln-MOFs). It explains the impact of the choice of organic linker on the final network topology, and it highlights the applications of Ln-MOFs in the catalysis of organic reactions.

The shoulder is the most complex joint in the human body. The use of arthroscopy has been employed in diagnosis and treatment of diseases that affect this joint. Depending on the surgeon’s preference and the disease treated, either beach chair or lateral decubitus can be used. Before undergoing surgery, even if it is minimally invasive, a complete diagnosis should be made. To achieve this, a complete history and physical examination must be undertaken combined with imaging techniques such as X-ray, ultrasound, CT, and MRI.

SSCI-VIDE+ING+CPG; International audience; This short critical review outlines the main synthetic strategies used in the designed synthesis of lanthanide-based metal organic frameworks (Ln-MOFs). It explains the impact of the choice of organic linker on the final network topology, and it highlights the applications of Ln-MOFs in the catalysis of organic reactions.

New manganese compounds [Mn(HphpzMe)(2)(H(2)phpzMe)(HCO(2))] (1), [Mn(2)(phpzMe)(2)(HphpzMe)(2)(OCH(3))]·2CH(3)OH (2), Na{[Mn(HphpzPh)(phpzPh)(MeOH)(2)](2)}(HCO(2)) (3), [Mn(HphpzPh)(2)(EtOH)(2)]ClO(4)·2EtOH (4) and [Mn(HphpzPh)(2)N(3)] (5) were synthesized and characterized with various techniques. 1, 4 and 5 are mononuclear manganese(III) compounds, 2 is a mixed-valence dinuclear manganese(III/IV) compound, and 3 is a trinuclear compound containing two manganese(III) ions and a sodium(I) ion. A remarkable feature is the spontaneous formation of the formate ion as a result of the methanol or methoxide oxidation in compounds 1 and 3. Using ethanol precludes the formation of the formate and compound 4 is obtained. The molecular structure of all compounds is stabilized by supramolecular interactions, including strong hydrogen bonding and π-π interactions.

Magnetic properties of new d-f cyanido-bridged 1D assemblies [RE(pzam)(3)(H(2)O)W(CN)(8)]·H(2)O (RE(III) = Gd, 1, Tb, 2, Dy, 3; pzam = pyrazine-2-carboxamide) were studied by temperature- and field-dependent magnetization measurements. No evidence for 3D interchain magnetic ordering is found above 2 K. Multiconfiguration ab initio calculations and subsequent modeling afforded simulation of the weak zero-field splitting effect in 1 and discussion of magnetic anisotropy in the f units of compounds 2 and 3. A semiquantitative corroboration with the experimental magnetic measurements is presented, performing the simulation of magnetic susceptibility vs temperature and magnetization vs field variation. The association into molecular and supramolecular architectures is analyzed by means of energy decomposition subsequent to the DFT calculations on idealized molecular models extracted from the experimental chain structure.

We present and develop alternative catalysts for biomass conversion and specifically lignin conversion into aromatics. Unlike the conventional CoMo and NiMo formulations, our catalysts can convert low-sulfur feedstocks. A set of five magnesia–alumina mixed oxides were screened in the hydrodealkylation of alkyl phenyl ethers as lignin model compounds. The typical selectivity to phenol is 30–75 %. Interestingly, we saw that the more basic the catalyst, the higher the selectivity for phenol. The results concur with the formation of phenoxide (PhO–) and RH3+ fragments on the catalyst surface. These can then react with H+ and H– species formed by the hydrogen dissociation on the MgO surface, giving phenol and hydrocarbons. We conclude that magnesia–alumina mixed oxides are attractive candidates for catalyzing lignin breakdown. These catalysts are highly stable, inexpensive, and readily available.

Open Access article., Two new d-f cyanido-bridged 1D assemblies [RE(pzam)3(H 2O)Mo(CN)8]·H2O (RE = Sm(iii), Er(iii)) were synthesized and their magneto-structural properties have been studied by field-dependent magnetization and specific heat measurements at low temperatures (≥0.3 K). Below ≈ 10 K the ground state of both the Sm(iii) and Er(iii) ions is found to be a Kramers doublet with effective spin S = 1/2. From analyses of the low-temperature magnetic specific heat and magnetization the exchange coupling between these RE(iii) effective spins and the Mo(v) spins S = 1/2 along the structural chains has been determined. It is found to be antiferromagnetic, with J∥/kB = -2.6 K and Ising-Heisenberg symmetry of the interaction (J∥/J = 0.3) for RE = Sm(iii), whereas the compound with RE = Er(iii) behaves as a pure XY chain, with J/kB = -1.0 K. For the compound [Sm(pzam)3(H2O)Mo(CN) 8]·H2O a small λ-type anomaly in the specific heat is observed at about 0.6 K, which is ascribed to a transition to long-range magnetic ordering induced by weak interchain interactions of dipolar origin. No evidence for 3D interchain magnetic ordering is found in the Er(iii) analogue. © The Royal Society of Chemistry 2011., This research was supported by a Veni grant fromthe Netherlands Organization for Scientific Research (NWO) to S. T. One of the authors (M. E.) thanks the Spanish MICINN for grants MAT2009-13977-C03 and CSD 2007-00010.

Rare-earth(III) complexes of the general formula [RE{(Hsal) 3 -tren} 2 ](CF 3 SO 3 )3·nCH 3 CN, where RE is Eu (1), Gd (2), and Tb (3), and (Hsal) 3 tren is tris[2-(salicylideneimino)ethyl]amine, have been synthesized and structurally characterized. X-ray crystallographic studies show that the rare-earth(III) center is coordinated by six oxygen atoms that belong to the phenolato groups of two (Hsal) 3 tren ligand molecules to give an unusual hexacoordinate geometry. The molecular structure is stabilized by strong intramolecular interactions established between the hydrogen atoms located on the three imino nitrogen atoms and the deprotonated phenol oxygen atoms of each ligand. Luminescence studies have indicated the presence of efficient nonradiative deactivation pathways in 1-3, and only a weak ligand emission was observed (λ exc = 275 nm, λ em = 545 nm) in all cases. Temperature-dependent magnetic susceptibility studies have shown that crystal field effects are dominant for complex 3, whilst small antiferromagnetic interactions have been observed in 2.

The synthesis of transition-metal and rare-earth clusters has become a very active research field, mainly because these compounds can behave as molecule-based magnets. The formation of such compounds strongly depends on the choice of the bridging ligand. This review covers the progress made by pyrazole-based ligands in the formation of new transition-metal and rare-earth clusters. Synthetic approaches, structural diversity and magnetic properties are described. The formation of other interesting supramolecular structures, such as metallocycles or metallohelicates is also described to emphasize the richness of this type of ligands.

A combination of density functional theory (DFT) calculations and Mössbauer spectroscopy has been used to determine that the magnetic easy-axis is coincident with its crystallographic c-axis in [Fe(pca)(2)(py)(2)] x py, where pac is the 2-pyrazinecarboxylate ligand. This easy-axis bisects the approximately axial O-Fe-O coordination axes of molecules adjacent to each other along the b-axis. In {[Fe(pca)(2)(H(2)O)] x H(2)O}(n) the easy magnetic axis is not coincident with any of its crystallographic axes nor with the Fe-O(water) coordination axis, but is coincident with one of the Fe...Fe axes in the crystal structure. The DFT calculations, which use the B3LYP functional and the 6-311++G(d,p) basis set, yield s-electron probability densities and electric field gradient tensors for the iron(II) ion that are in excellent agreement with the observed iron-57 Mössbauer spectral isomer shifts and quadrupole interactions. The gas phase results are very similar for calculations based either on the X-ray structures of the two complexes or on their optimized structures; the optimized structures indicate that the iron to ligand bond distances increase in the absence of any solid-state lattice interactions. The results of a normal coordinate vibrational mode analysis of the two optimized structures are compared with the observed infrared spectra.

New mononuclear compounds of the ligand 1-(2-hydroxyphenyl)-3-phenylpropane-1,3-dione (H2L) with Cu(II) and several lanthanoid(III) ions, where Ln(III) = Pr, Nd, Eu, Gd, have been synthesized and characterized by spectroscopic methods and X-ray crystal structure determinations. In all compounds, the ligand coordinates in a bidentate chelating manner, using the diketone function. In the [Cu(HL)2], the coordination geometry of Cu(II) ion is slightly distorted square-planar; two strong intramolecular (OH⋯O) hydrogen-bonding interactions are established between the phenolate group and the neighboring ketone function. The lanthanoid(III) compounds have the general formula [Ln(HL)3(CH3OH)2] · CH3OH · 2H2O; the lanthanoid(III) ion (Ln) is eight-coordinated and the coordination geometry is based on a distorted square-antiprism. In addition to the intramolecular hydrogen bonding (OH⋯O), intermolecular hydrogen-bonding interactions are also present between the coordinated methanol molecule and the non-coordinated methanol molecule giving rise to a three-dimensional network.

The synthesis, crystal structure, and magnetic properties of three new manganese(III) clusters are reported, [Mn 3(mu 3-O)(phpzH) 3(MeOH) 3(OAc)] (1), [Mn 3(mu 3-O)(phpzMe) 3(MeOH) 3(OAc)].1.5MeOH (2), and [Mn 3(mu 3-O)(phpzH) 3(MeOH) 4(N 3)].MeOH (3) (H 2phpzH = 3(5)-(2-hydroxyphenyl)-pyrazole and H 2phpzMe = 3(5)-(2-hydroxyphenyl)-5(3)-methylpyrazole). Complexes 1- 3 consist of a triangle of manganese(III) ions with an oxido-center bridge and three ligands, phpzR (2-) (R = H, Me) that form a plane with the metal ions. All the complexes contain the same core with the general formula [Mn 3(mu 3-O)(phpzR) 3] (+). Methanol molecules and additional bridging ligands, that is, acetate (complexes 1 and 2) and azide (complex 3), are at the terminal positions. Temperature dependent magnetic susceptibility studies indicate the presence of predominant antiferromagnetic intramolecular interactions between manganese(III) ions in 1 and 3, while both antiferromagnetic and ferromagnetic intramolecular interactions are operative in 2.

The reaction of the ligand 1,4-bis(pyridine-2-carboxamido)butane (L) with RECl3 afforded complexes of general formula [RE(L)1.5Cl2(CH3OH)]Cl·nS (RE = Pr, Nd, Eu, Tb; n = 4, S = H2O; n = 5, S = CH3OH). The structural determination reveals that complexes [RE(L)1.5Cl2(CH3OH)]Cl·5CH3OH (RE = Nd 2b, Eu 3b) are isomorphous, crystallizing in the monoclinic system, space group P21/n; they possess a 2D architecture with the rare-earth ion in an eight-coordination geometry. By exposure to air, the lattice methanol molecules are easily replaced by water molecules to form the analogues [RE(L)1.5Cl2(CH3OH)]Cl·4H2O (RE = Pr 1, Nd 2a, Eu 3a, Tb 4) as indicated by elemental analysis, IR, and thermogravimetric analysis. Photophysical studies on the EuIII and TbIII complexes showed that excitation into the ligand-centered π→π* transition results in the characteristic visible luminescence from EuIII at 614 nm and TbIII at 545 nm. The magnetic properties were also investigated and show that crystal field effects are dominant. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A novel linear bis(chlorido)-bridged Cu(II) compound with the ligand 7-azaindole (abbreviated as Haza) have been synthesized and fully characterized by spectroscopy, EPR and X-ray structure analysis. The geometry around the Cu(II) ion in the compound [Cu–μ-Cl2(Haza)2]n, is distorted octahedral with the basal plane formed by two chloride anions with a Cu–Cl distance of 2.286(1) A and two nitrogen atoms of two trans-chelating Haza ligands with a Cu–N distance of 2.042(4) A. The apical positions is formed by two chloride anions of a neighbouring unit at a distance of 3.143(2) A. The Cu–Cl–Cu angle is 90.09(5)°, while the Cu–Cu distance is 3.8890(8) A. The EPR powder spectrum appears as rhombic, displaying some extra features which were assigned to the differences in orientation of chains in the lattice, as their intensity appears to decrease on powdering. The magnetic susceptibility measurements, recorded from 5 to 300 K, agree with a very weak antiferromagnetic interaction in a chain with J = −2.6 cm−1.

New complexes with 5(3)-(2-hydroxyphenyl)-3(5)-methylpyrazole (H(2)phpz), [Co-2(H(2)phpz)(Hphpz)(2)(phpz)(2)](.)3CH(3)CN (1), [Ni(Hphpz)(2)] (2) and [Cu(HphpZ)(2)] (3), were synthesized and structurally characterized. The ligand coordinates in the form of 3-(2-hydroxyphenyl)-5-methylpyrazole in all cases, except for one ligand in the Co-III complex, where it coordinates in the 5-(2-hydroxyphenyl)-3-methylpyrazole mode. Crystallographic analysis revealed that 1 contains two chemically and crystallographically distinct cobalt(III) ions triply bridged by one phenoxide and two pyrazolate groups, giving rise to a [Co-2(N-N)(2)O] core with a (CoCo)-Co-... distance of 3.154 angstrom. Additionally, the H(2)phpz ligand shows four different coordination modes with the metal ions, demonstrating its versatility. The dinuclear unit of 1 is stabilized by strong intramolecular N-(HO)-O-... hydrogen-bonding interactions involving the phenol oxygen atom of the H(2)phpz ligand and the N-H functionality of the pyrazole ring. The crystal structure of the isomorphous complexes 2 and 3 reveals the presence of centrosymmetric mononuclear units with the MN2O2 [M = Ni-II (2), Cu-II (3)] chromophore displaying a slightly distorted square-planar geometry. The mononuclear structures of 2 and 3 are further stabilized by intramolecular hydrogen bonds established between the acid N-H group as donor and the phenoxide group of the H(2)phpz ligand as acceptor. Spectroscopic studies, ESI-MS and cyclic voltammetry were performed, supporting the crystallographic analysis. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).

Iron complexes of two ligands, HphoxCOOH and HphoxiPr, have been synthesized and characterized by crystal structure analyses. The complexes (HNEt3)2[Fe(phoxCOO)2](ClO4) and [Fe(phoxiPr)3] are reported. Reactions of the ligands rac-HphoxCOOH and rac-HphoxiPr with iron(II) or iron(III) perchlorate result in the formation of iron(III) complexes with pseudo-octahedral geometry around the metal center. The iron complex obtained from rac-HphoxCOOH crystallized in the centrosymmetric space group Cmca. The two ligands are bound in a tridentate manner generating a meridional coordination with both dianionic ligands on a metal center having the same chirality; due to the center of symmetry the complex with opposite chirality is also present. The complex (HNEt3)2[Fe(phoxCOO)2](ClO4) is the first accurate structural model of the iron complex of a siderophore analog commonly observed in mycobactins. The three didentate ligands in the complex [Fe(phoxiPr)3] are bound with like atoms in a meridional manner to the metal center. The metal ion is surrounded by two ligands of the same chirality and one ligand of opposite chirality (ie. RRS or SSR); due to the presence of a center of symmetry both isomers are present in the crystal structure. The complex (HNEt3)2[Fe(phoxCOO)2](ClO4) shows promising activity in the oxidation of alkanes, such as toluene, ethylbenzene and cumene, while the complex [Fe(phoxiPr)3] does not show any catalytic activity in alkane oxidations under the conditions tested. The complex (HNEt3)2[Fe(phoxCOO)2](ClO4) is reasonably efficient in the conversion of H2O2 to oxidation products.

Item does not contain fulltext The reactions of pyridine-2,6-dicarboxamide with europium(III) and terbium(III) triflates led to the formation of mononuclear complexes of formula [Ln(pcam)(3)](CF3SO3)(3) (Ln = Eu 1, Tb 2; pcam stands for pyridine-2,6-dicarboxamide). From single-crystal X-ray diffraction analysis, the complexes were found to be isomorphous and isostructural. The [Ln(pcam)(3)](3+) cations and triflate counterions are connected by intermolecular hydrogen bonds, resulting in a 3D network structure. Both the europium(III) and terbium(III) complexes exhibit efficient ligand sensitized luminescence in the visible region with lifetimes of 1.9 ms and 2.2 ms, respectively, in the solid state. (c) 2006 Elsevier B.V. All rights reserved.

We present a new coordination polymer, {[VO(pzdc)(H2O)(2)] H2O}(n), built from vanadyl and pyrazine-2,5-dicarboxylate (pzdc) ions. It consists of a one-dimensional chain of vanadyl ions linked by pzdc ions. The carboxylate groups show monodentate coordination, while the pyrazine ring is present both in non-coordinated and coordinated modes. This novel structure is stabilized by an intricate network of hydrogen bonds. The material is highly robust, and thermally stable up to 400 K. It is also antiferromagnetic, with a maximum magnetic susceptibility at ca. 50 K. The orbital shape and population analysis by means of DFT analysis confirm the pi-acceptor role of the aromatic nitrogen function of the ligand, while the oxygen-based moieties (carboxylates from pzdc, the aqua ligands and oxo from V=O group) behave as normal donors. Charting the density flow related with significant transitions computed by time-dependent DFT, we determined the ligand-to-metal charge transfer processes. The topology of the chain complex implies two different types of connecting bridges. Using Broken Symmetry DFT modelling gives evidence for two different exchange coupling mechanisms between the vanadyl ions along each of these two molecular bridges. One is strongly antiferromagnetic, practically reducing the chain to 'vanadyl dimers'. The other is almost uncoupled, due to the large distance between the vanadyl ions.

A ratiometric thermometer based on a mixed-metal Ln(III) metal-organic framework is reported that has good sensitivity in a wide temperature range from 4 to 290 K and a quantum yield of 22% at room temperature. The sensing mechanism in the europium-doped compound Tb0.95Eu0.05HL (H4L = 5-hydroxy-1,2,4-benzenetricarboxylic acid) is based not only on phonon-assisted energy transfer from Tb(III) to Eu(III) centers, but also on phonon-assisted energy migration between neighboring Tb(III) ions. It shows good performance in a wide temperature range, especially in the range 4-50 K, reaching a sensitivity up to 31% K(-1) at 4 K.

Design and synthesis of cyanido-bridged d–f molecular assemblies, often accessible via self-assembly of anionic building-block [M(CN)6]3− and lanthanide ions in the presence of blocking ligands, is of significant utility in the preparation of molecule-based magnets. The ability of the cyanido ligand to link various metal ions leads to a wide diversity of structural architectures ranging from discrete polynuclear complexes to fascinating three-dimensional networks. In this review, examples of cyanido-bridged d–f polynuclear complexes are discussed in terms of their structures, and their magnetic properties. It is shown that the efforts to synthesize d–f cyanido-bridged assemblies have lead to a great variety of supramolecular architectures created by the interplay of coordinative, hydrogen bonding, and π–π stacking interactions. Furthermore, the magnetic properties of these assemblies will be discussed in terms of the magnetic exchange coupling between lanthanide(III) and transition metal ions.

The synthesis and characterization is reported of four new iron(III) complexes, [Fe(L1)](ClO4) (1), [Fe(L1)](BF4) (2), [Fe(L2)](ClO4) (3), [Fe(L2)](BF4) (4) with the N4O2-donor hexadentate Schiff-base ligands (L1 = N,N′,N″,N‴-1,5,8,12-tetraazadodecane-bis(salicylaldiminato), L2 = N,N′,N″,N‴-1,5,8,12-tetraazadodecane-bis(3-methoxysalicylaldiminato)) obtained from salicylaldehyde, or a 3-methoxysalicylaldehyde. The iron(III) complexes have been prepared with different counter ions, i.e., ClO 4 - and BF 4 - , and characterized by different experimental techniques: X-ray crystallography, IR, ligand field spectroscopy, EPR, cyclic voltammetry, and magnetic susceptibility measurements. The molecular structure of the complexes is built up by complex cations [Fe(L1)]+ or [Fe(L2)]+ and counter anions ClO 4 - or BF 4 - , and has been proven by X-ray diffraction on single crystals for 1, 3 and 4. In all cases, the coordination geometry around the iron(III) ion is distorted octahedral with the iron to phenoxo oxygen bonds being trans to each other. In the crystal lattice, the mononuclear entities are organized into infinite 1D chains due to the hydrogen-bonding interactions involving the secondary amine functions and one oxygen/fluorine atom of a counter anion. In acetonitrile, all complexes exhibit a quasi-reversible one-electron reduction process Fe(III) → Fe(II), with half-wave potential E1/2 = −0.5 V. The EPR spectra of 1–4 clearly indicate a low-spin d5 (S = 1/2) electronic configuration with a rhombic symmetry. In all cases, the temperature dependent magnetic properties (5–300 K) agree with the presence of one unpaired electron (S = 1/2) and with moderate orbital contribution due to the orbitally degenerate electronic ground state (2T2g) of the octahedral iron(III) complexes.