Rare Earth Metal Salts Research Articles

One-pot synthesis of 1,5,3-oxathiazepanes via the three-component condensation of primary amines, formaldehyde and 2-mercaptoethanol

The three-component condensation reaction of primary amines, formaldehyde and 2-mercaptoethanol using salts of transition and rare earth metals as catalysts was developed to obtain a new 7-membered heterocyclic structural building block, 1,5,3-oxathiazepanes, in good to excellent yields. The structure of the heterocyclic fragment was confirmed by NMR spectroscopy.

ION SOLVATION IN SALTS OF BIOLOGICALLY IMPORTANT RARE EARTH METALS WITH AQUEOUS SUGAR ALCOHOL (SORBITOL) MIXED-SOLVENT SYSTEMS

Acoustic investigations have examined the salts of rare earth metals, such as lanthanum(III) chloride, in sorbitol-water mixed solvent systems of different concentrations at 303.15K temperature and 1 atmospheric pressure. Various parameters have been calculated from the measured values of ultrasonic velocity, density and viscosity data. These parameters help to characterize the ion-solvent interaction and are also supportive of the structure-promoting tendency in the present solute-mixed solvent system. The limiting solvation number, Sn0, of lanthanum(III) chloride is maximum in water, rather than in sorbitol-water mixed solvent systems, which is attributed to an interesting outcome regarding the behaviour of sorbitol and water in comparison to other saccharides.

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx3-, featured a size-sensitive aperture formed of its three η2-(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)]2 species. Differences in the equilibrium constants Kdimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation.

Sensitization of HoIII and SmIII luminescence by efficient energy transfer from antenna ligands: Magnetic, visible and NIR photoluminescence properties of GdIII, HoIII and SmIII coordination polymers

Hydrothermal reactions of lanthanide metal salts with 2-sulfoterephthalate (2-stp) and 4,4′-bipyridine (4,4′-bipy) led to three coordination polymers, {[Ln(2-stp)(4,4′-bipy)(H2O)]·(H2O)}, [Ln=Gd (1), Ho (2) and Sm (3)]. Their structures have been established by X-ray single crystal diffraction. Complexes 1–3 are isostructural with 2D framework in which all LnIII atoms are nine-coordinated. All these 2D layers are further interlinked via hydrogen bonds resulting in 3D architecture. The solid-state photoluminescence measurements display the characteristic luminescence of Ho (2) and Sm (3), which is due to efficient energy transfer from the ligands to the central LnIII ions via an “antenna effect”. Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field for 1–3 is studied which reveal mainly the presence of antiferromagnetic interactions and the thermal depopulation of Stark sublevels together with crystal field affects.

First radical cаtion salt of bis(ethylenedithio)tetrathiafulvalene with organic anion [С(NCN)2NH2]–: synthesis, structure, and conducting properties

The electrochemical oxidation of bis(ethylenedithio)tetrathiafulvalene (ET) in the presence of simple dicyanamide salts of rare-earth metals with the general formula M[N(CN)2]3 (M = Gd3+, Dy3+, and Ho3+) as electrolytes was studied for the first time. A novel radicalcаtion salt α-ЕТ2[С(NCN)2NH2] with the unexpected (2,1-dicyano)guanidine anion was synthesized. The crystal structure of the salt and its conducting properties were studied. The structure of the salt is layered with alternating conducting radical-cation and insulating anionic layers. The cationic layers of the α-type are formed by two crystallographically independent radical-cations of ET of various charges. The anionic layers are formed of [С(NCN)2NH2]– anions linked by hydrogen contacts into chains. The crystals of ЕТ2[С(NCN)2NH2] demonstrate a semiconducting character of conductivity in a temperature range of 300—100 K.

Specific features of determinations of the composition of high-purity lanthanide crystal hydrates

Problem of the determination of the composition of high-purity rare-earth metal salts is discussed. Prospects of the application of direct chemical methods to the determination of the water content of crystal hydrates of rare-earth metal salts used in the GET 173-2013 State Primary Standard of Mass Fraction and Mass (Molar) Concentration of Water in Solid and Liquid Substances and Materials are studied.

Mobile nanostructures (cybotactic groups) as a basis of generalised phenomenological model of aqueous electrolyte solutions

In this paper, we briefly review our researches into concentrated electrolyte solutions by means of a proposed phenomenological model. Electrolyte solutions are complex systems with a multitude of interactions. However, totality of interactions in solution is reflected in its constitution. The description of solution structure includes all parameters that define short-range ordering of particles, a full description of all possible coexistent vibrationally averaged structures (V-structures). We believe that information about the presence of the concentration ranges with different dominant structures and boundaries may be derived from the solubility polytherm (phase diagram) of the water-salt system. The boundary concentration corresponds to the eutectic composition (EC). In the range of pre-eutectic concentrations the dominant structure is the proper structure of water, and ion hydration is the major type of interaction between components. A crystalline hydrate or anhydrous salt crystallises at reduced temperatures from solutions with post-eutectic concentrations; hence, the dominant solute included V-structures are the structures of corresponding crystalline hydrate or quasi-crystalline fragments of anhydrous salt. For above-discussed spatial ordering of particles we used Stewart's term 'cybotactic group' (CG), which is a nanodimensional mobile V-structure that corresponds to the unit cell of a solid phase, which crystallises from solution under freezing. Analysis of concentration dependences of structural-sensitive properties (parameters) serve as information source about structural changes in solution, and 'special points' or singularities as the concentration boundaries of structural changes in solution correspond to eutectic and peritectics on solubility diagram. We proposed a new method of sounding to probe some peculiarities and differences in the solution structure. This method consists of monitoring of structural and dynamical features of new micro components introduced into the system under investigation. As such micro components one can use small additives of salts of transition and rare-earth metals. The structure of solution has a pronounced effect on the condition of complex-forming cations, which are presented as additives. If dominant structure (CG) has changed, there are alterations in structural and dynamical parameters of micro components, thus indicating that their behaviour 'obeys' the overall structural rearrangement in the solution. Such alterations of micro components can serve for probing some differences in the dominant structure of the supporting solution.

Synthesis, structure and adsorption properties of lanthanide-organic frameworks with pyridine-3,5-bis(phenyl-4-carboxylate).

Under solvothermal conditions, reactions of pyridine-3,5-bis(phenyl-4-carboxylic acid) (H2L) with lanthanide metal salts give rise to three new metal-organic frameworks (MOFs) with the formula {[Ln4(L)3(μ3-OH)4(H2O)4]·(NO3)2·solvent}n [Ln = Er (1), Yb (2) and Lu (3)]. The complexes were characterized by single crystal and powder X-ray diffraction, IR and thermogravimetric analyses. They have the same two-fold interpenetrating three-dimensional (3D) framework structures with [Ln4(COO)6(μ3-OH)4(H2O)4] clusters as secondary building units (SBUs) and a rare 6-connected lcy topology with the point (Schläfli) symbol of {3(3)·5(9)·6(3)}. Interestingly, 1-3 show selective and hysteretic sorption of CO2 over N2, and the photoluminescence properties of the complexes were also investigated.

Lanthanide-tricarboxylate frameworks: Synthesis, structure and photoluminescence property

Reactions of tricarboxylate ligands biphenyl-3,4′,5-tricarboxylic acid (H3L1) and [1,1′:3′,1″-terphenyl]-4,4″,5′-tricarboxylic acid (H3L2) with the lanthanide metal salts under solvothermal conditions give rise to five new lanthanide-organic frameworks. Complexes {[Ln(L1)(H2O)(DMF)]·DMF·H2O}n [Ln = La (1), Ce (2) and Sm (3)] with (L1)3− have the same framework structures, while the frameworks based on the ligand (L2)3− with formula {[Ln(L2)(H2O)2]·2DMF·14H2O}n [Ln = Sm (4) and Gd (5)] are also isostructural. All the complexes have binuclear paddlewheel [Ln2(CO2)4] clusters as the secondary building units, which are further linked together by the organic ligands to form three-dimensional (3,6)-connected frameworks. In addition, thermal stability and photoluminescence properties of 1–5 were investigated.

Solvation Mechanism of Task-Specific Ionic Liquids in Water: A Combined Investigation Using Classical Molecular Dynamics and Density Functional Theory.

The solvation behavior of task-specific ionic liquids (TSILs) containing a common, L-histidine derived imidazolium cation [C20H28N3O3](+) and different anions, bromide-[Br](-) and bis(trifluoromethylsulfonyl)amide-[NTF2](-), in water is examined, computationally. These amino acid functionalized ionic liquids (ILs) are taken into account because of their ability to react with rare earth metal salts. It has been noted that the TSIL with [Br](-) is more soluble than its counterpart TSIL with [NTF2](-), experimentally. In this theoretical work, the combined classical molecular dynamics (CMD) and density functional theory (DFT) calculations are performed to study the behavior of the bulk phase of these two TSILs in the vicinity of water (H2O) molecules with different concentrations. Initially, all the constructed systems are equilibrated using the CMD method. The final structures of the equilibrated systems are extracted for DFT calculations. Under CMD operation, the radial distribution function (RDF) plots and viscosity of TSILs are analyzed to understand the effect of water on TSILs. In the DFT regime, binding energy per H2O, charge transfer, charge density mapping, and electronic density of states (EDOS) analyses are done. The CMD results along with the DFT results are consolidated to support the hydrophilic and hydrophobic nature of the TSILs. Interestingly, we have found a strong correlation between the viscosity and the EDOS results that leads to an understanding of the hydration properties of the TSILs.

Rare earth and transitional metal colloidal supercapacitors

The search of electrode materials with high electrochemical activity is one of key solutions to actualize both high energy density and high power density in a supercapacitor. Recently, we have developed one novel kind of rare earth and transitional metal colloidal supercapacitors, which can deliver higher specific capacitance than electrical double-layer capacitors (EDLC) and traditional pseudocapacitors. The electrode materials in colloidal supercapacitors arin colloidal supercapacitors aree in-situ formed electroactive colloids, which were transformed from commercial rare earth and transitional metal salts in alkaline electrolyte by chemical and electrochemical assisted coprecipitation. In these colloidal supercapacitors, multiple-electron Faradaic redox reactions can be utilized, which can deliver ultrahigh specific capacitance often larger than one-electron capacitance. Multiple-valence metal cations used in our designed colloidal supercapacitors mainly include Ce3+, Yb3+, Er3+, Fe3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Sn2+ and Sn4+. The colloidal supercapacitors can be served as the promising next-generation high performance supercapacitors.

Extraction of rare earth metals, uranium, and thorium from nitrate solutions by binary extractants

The interphase distribution of the salts of rare earth metals (REMs) that coexist in systems containing dialkyl phosphinate and dialkyl dithiophosphinate of quaternary ammonium base (QAB) was studied. It is shown that, in principle, binary extractants based on derivatives of phosphinic acids and QAB can be used to separate REMs from the associated metals (uranium and thorium), as well as to separate uranium and thorium. A numerical investigation of the application prospects of the binary extractants for extracting and separating REMs and uranium using liquid pseudomembranes has been performed; the prospects of developing these processes have been demonstrated.

A Catalyst Platform for Unique Cationic (Co)Polymerization in Aqueous Emulsion.

Sodium dodecyl benzene sulfonate (DBSNa) surfactants, with a polydisperse and hyperbranched structure, combined with different rare earth metal salts generate highly water-dispersible Lewis acid surfactant combined catalysts (LASCs). This platform of new complexes promotes fast, efficient cationic polymerization of industrially relevant monomers in direct emulsion at moderate temperature. The process described here does not require high shearing, long polymerization time, or large catalyst content. It allows the reproducible generation of high-molar-mass homopolymers of pMOS, styrene, and isoprene, as well as random or multiblock copolymers of the latter two, in a simple and straightforward one-pot reaction.

A Catalyst Platform for Unique Cationic (Co)Polymerization in Aqueous Emulsion

AbstractSodium dodecyl benzene sulfonate (DBSNa) surfactants, with a polydisperse and hyperbranched structure, combined with different rare earth metal salts generate highly water‐dispersible Lewis acid surfactant combined catalysts (LASCs). This platform of new complexes promotes fast, efficient cationic polymerization of industrially relevant monomers in direct emulsion at moderate temperature. The process described here does not require high shearing, long polymerization time, or large catalyst content. It allows the reproducible generation of high‐molar‐mass homopolymers of pMOS, styrene, and isoprene, as well as random or multiblock copolymers of the latter two, in a simple and straightforward one‐pot reaction.

An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359.

Highly efficient stabilisation of meta-ethynylpyridine polymers with amide side chains in water by coordination of rare-earth metals.

An amphiphilic meta-ethynylpyridine polymer with chiral amide side chains was developed. The polymer was prepared by sequential Sonogashira reactions, and the product was soluble in polar and apolar solvents. The additive effects of metal salts on the polymer were examined in water and aqueous EtOH on the basis of UV-vis and CD spectra. The enhancement of the positive Cotton effect and hypochromism around 360 nm occurred by the addition of various metal salts, indicating the coordination of the cations to the amide side chains of the polymer to stabilise the helical structure. Among them, rare-earth metal salts, especially Sc(OTf)3 showed more efficient additive effects probably because of its strong coordination ability even in water. Positive cooperativity was observed for the coordination of Sc(OTf)3 to the polymer in aqueous EtOH.

Electrochemical analysis of diffusion behavior and nucleation mechanism for Dy(II) and Dy(III) in phosphonium-based ionic liquids

Abstract In this study, the solubility, diffusion coefficient, and nucleation behavior of rare-earth metal complexes in a phosphonium-based ionic liquid (IL) were investigated in order to analyze the electrodeposition mechanism of the Dy metal. For the solubility of Dy(TFSA) 3 and Nd(TFSA) 3 in an IL, the temperature dependence was also evaluated from 340 to 470 K using ultraviolet–visible spectroscopy. The solubility curves obtained for Dy(III) and Nd(III) have similar tendencies and show a relatively good fit with the modified Apelblat equation. A series of thermodynamic parameters (Δ sol G ∞ , Δ sol H ∞ , and Δ sol S ∞ ) were also estimated, and the results reveal that the dissolution process of rare-earth metal salts in polar ILs is controlled by enthalpy. For electrochemical analyses, cyclic voltammetric measurements reveal that the reduction process of Dy(III) proceeds in two steps by way of Dy(II) [Dy(III) + e − → Dy(II), Dy(II) + 2e − → Dy(0)], when the IL contains a small amount of water ( −1 , respectively. In addition, the nucleation and growth processes of Dy(0) were evaluated from chronoamperometry. These results indicate that the nucleation mechanism of Dy(0) changes from instantaneous nucleation to progressive nucleation when the applied overpotential becomes more negative than the deposition peak potential of Dy(0), as estimated from a voltammogram. Furthermore, electrowinning of the Dy metal from 0.1 mol dm −3 Dy(III) in an IL was carried out using a three-electrode system. The surface morphology of the electrodeposits showed accumulated round particles with 0.8–0.9 μm diameter, as observed by a scanning electron microscope. Most of the Dy electrodeposits were in the metallic state, while a part of their top surface was in the oxidation state, as evaluated from the EDX, XPS, and XRD analyses.

An Efficient Catalyst System at Mild Reaction Conditions Containing Rare Earth Metal Complexes

AbstractAn efficient rare earth metal complex‐catalyzed cycloaddition reaction of CO2 with propylene oxide using Hdpza (di(2‐pyrazyl)amine) as a N‐donor ligand has been accomplished in good to excellent yields with high selectivity. The effects of different rare earth metal salts, ligands and reaction conditions were examined. Catalytic reaction tests demonstrated that the incorporation of ErCl3 and Hdpza can significantly enhance the catalytic reactivity of the TBAB (nBu4NBr, tetra‐n‐butyl ammonium bromide) towards cycloaddition reaction of CO2 and propylene oxide that produce cyclic carbonates under mild conditions without any co‐solvent.

Crystal structure of nonaaqua[bis(μ2-pyridine-2,4,6-tricarboxylato- κ3O,N,O:(O')dilutetium(III)]trihydrate, Lu2(H2O)9(ptc)2·3H2O, C16H28Lu2N2O24

Abstract C16H28Lu2N2O24, triclinic, P1̄ (no. 2), a = 7.602(2) Å, b = 10.417(2) Å, c = 17.374(4) Å, α = 92.32(3)°, β = 92.08(3)°, γ = 95.74(3)°, V = 1366.7 Å3, Z = 2, Rgt(F) = 0.0489, wRref(F2) = 0.1229, T = 293 K.

Using metal-ligand interactions to access biomimetic supramolecular polymers with adaptive and superb mechanical properties.

The development of polymer materials that exhibit excellent mechanical properties and can respond to environmental stimuli is of great scientific and commercial interest. In this work, we report a series of biomimetic supramolecular polymers using a ligand macromolecule carrying multiple tridentate ligand 2,6-bis(1,2,3-triazol-4-yl)pyridine (BTP) units synthesized via CuAAC in the polymer backbone together with transition and/or lanthanide metal salts. The metal-ligand complexes phase separate from soft linker segments, acting as physical crosslinking points in the materials. The metallo-supramolecular films exhibit superb mechanical properties, i.e., high tensile strength (up to 18 MPa), large strain at break (>1000%) and exceptionally high toughness (up to 70 MPa), which are much higher than those of the ligand macromolecule and are tunable by adjusting the stoichiometric ratio of Zn2+ to Eu3+ and the stoichiometry of metal ion to ligand. The metal-ligand hard phase domains are demonstrated to be thermally stable but mechanically labile, similar to the behaviors of covalent mechanophores. The thermal stability and mechanical responsiveness are also dependent on the compositions of metal ions. The disruption of the hard phase domains and the dissociation of metal-ligand complexes under stretching are similar to the unfolding of modular domains in modular biomacromolecules and are responsible for the superb mechanical properties. In addition, the biomimetic metallo-supramolecular materials display promising responsive properties to UV irradiation and chemicals. These well designed, created and characterized robust structures will inspire further accurate tailoring of biomimetic responsive materials at the molecular level and/or nanoscale.