Lanthanide Research Articles

Refined structural studies on the fluorite-related polymorphs of sol-gel undoped and Eu3+-doped yttrium tantalates.

Compounds with the general formula RE3MO7 (RE = rare earth ions; M = Ta, Nb, Sb, Ru, Ir, Os, Re, etc.), crystallize as a fluorite-related structure, forming polymorphs with different space groups. The space group strongly depends on the RE3+ and M5+ ionic radii and processing conditions. Structural characterization is well-established for the lanthanide series, but literature studies have divergent views about how to attribute yttrium tantalate (Y3TaO7) space groups-some authors have described the Y3TaO7 structure as orthorhombic and belonging to space group C2221 or Ccmm, whereas others have assigned a cubic Fm3̄m structure to it. Here, we have characterized the structure of undoped and Eu3+-doped Y3TaO7 (0.1 to 50 mol% of Eu3+) samples synthesized by the sol-gel method that crystallized as a cubic disordered fluorite-type structure, space group Fm3̄m. Their powder X-ray diffraction measurements, Rietveld analyzes and Raman spectra were used as a conclusive technique of the structural properties. We have also investigated whether a secondary phase (M'-YTaO4) emerged in the samples and compared the phase composition of each sample to their Raman spectra. Low-temperature photoluminescence measurements (∼15 K) using Eu3+ as a structural probe helped us analyze the inhomogeneous broadening observed in the emission spectra. These measurements can be used as an important tool to attribute the crystalline phases of rare earth tantalates and niobates.

Elucidating ultranarrow 2F7/2 to 2F5/2 absorption in ytterbium(iii) complexes.

Achieving ultranarrow absorption linewidths in the condensed phase enables optical state preparation of specific non-thermal states, a prerequisite for quantum-enabled technologies. The 4f orbitals of lanthanide(iii) complexes are often referred to as "atom-like," reflecting their isolated nature, and are promising substrates for the optical preparation of specific quantum states. To better understand the photophysical properties of 4f states and assess their potential for quantum applications, theoretical building blocks are required for rapid screening. In this study, an atomic-level perturbative calculation (i.e., spin-orbit crystal field, SOCF) is applied to various Yb(iii) complexes to investigate their linear absorption and emission through a fitting mechanism of their experimentally determined transition energies and oscillator strengths. In particular, the optical properties of (thiolfan)YbCl(THF) (thiolfan = 1,1'-bis(2,4-di-tert-butyl-6-thiomethylenephenoxy)ferrocene), a recently reported complex with an ultranarrow optical linewidth, are computed and compared to those of other Yb(iii) compounds. Through a transition energy sampling study, major contributors to the optical linewidth are identified. We observe particularly isolated f-f transitions and narrow linewidths, which we attribute to two distinct factors. Firstly, the ultra-high atomic similarity of the orbitals involved in the optical transition, along with the presence of an anisotropic crystal field, collectively contribute to the observed narrow transitions. Secondly, we note highly correlated excited-ground energy fluctuations that serve to greatly suppress inhomogeneous line-broadening. This article illustrates how SOCF can be used as a low-cost method to probe the influence of crystal field environment on the optical properties of Yb(iii) complexes to assist the development of novel lanthanide series quantum materials.

Формы переноса РЗЭ фторидно-карбонатно-хлоридными охлаждающимися гидротермальными флюидами в присутствии барита и целестина (термодинамическое моделирование)

A thermodynamic study was carried out in order to determine the forms of transport for the entire series of lanthanides and their ratio with changing parameters of a hydrothermal fluid of moderate concentrations of chloride, carbonate and fluoride components. Hydrothermal solution, cooling from 500 to 100 ∘C, affected barite and celestine, which are used as a source of sulfate sulfur, monazite as a source of rare earth elements (REE) and phosphorus, and calcite as a source of calcium. It has been established that, under weakly acidic (pH about 4.1) conditions, the equilibrium mineral association is represented by rare earth fluorite, monazite, rare earth fluorapatite, and strontiobarite. In the high-temperature region for light and medium REE, the leading is the first chlorocomplex LnCl+2. For heavy REE, the second fluorine complex LnF+2 takes the first place, except for terbium and dysprosium, for which a sharp predominance of the sulfate complex is revealed. A special picture is observed at 100 ∘C: the leading position is occupied by Ln+3 for both light and heavy REE. In the case of a near neutral weakly alkaline fluid (pH about 7.1), the equilibrium mineral association is represented by calcite, monazite, REE-fluorite, REE-fluorapatite, strontiobarite, and strontianite. The appearance of the latter in natural associations may serve as an indication of the increased alkalinity of the ore-forming environment. In an equilibrium weakly alkaline fluid up to 200 ∘C, hydroxocomplexes are prevalent for all REEs with the ratio Ln(OH)03> Ln(OH)+2. The first chloro complex for light REE at 500–400 ∘C, and the second fluoro complex for medium and heavy REEs follow them. At 100 ∘C, the concentration of hydroxocomplexes sharply decreases, and fluorine and carbonate complexes come to the fore. In general, there is an increased stability of the first chlorocomplex in the high-temperature region, and with decreasing temperature, the role of REE fluorocomplexes increases. Two variants of acidity-alkalinity calculations presumably correspond to modeling of two types of fluids: greisenizing – weakly acidic and carbonatite-forming – weakly alkaline.

Active Diatomic Pairs Induced Interlayer Spacing Engineering in 2D Materials for Highly Efficient Energy Conversion Device

Ammonia, the second largest commercialized synthetic chemical in the world, is widely used for fertilizer and all nitrogen-atom-containing chemicals production. Energy conversion devices by electrochemical nitrate reduction reaction (eNO3RR) offer a green and appealing approach for sustainable ammonia synthesis but hindering by the multi-step chemical reaction and competitive hydrogen generation. To this end, exploring efficient nitrate-to-ammonia conversion devices play a critical role in developing ammonia electrosynthesis. Two-dimensional (2D) materials, like MoS2 and SnS2, have been considered promising energy electrocatalytic materials owing to the advantages of large specific areas that not only provide much more active sites but act as appropriate support to combine other materials. Recently, interlayer engineering on 2D materials has attracted intense interest from scientists because it could tune the chemical affinity of absorbates, which determines the energy barriers during multi-step electrocatalysis device. Therefore, it is valuable to investigate the effect of interlayer spacing in 2D materials on eNO3RR. Active diatomic A-B pairs, such as diatomic Pt-Ce and Pd-Ce pairs, have strong interactions that can be introduced into 2D materials to trigger the interlayer spacing change. For example, the lanthanide series rare earth element (Ce) can be a potential candidate to achieve interlayer expansion since it has a relatively higher atomic radius than most of the atoms, while intercalating Pt or Pd can close the interlayer spacing through solid interaction. In this work, by introducing active diatomic Pt-Ce and Pd-Ce pairs into SnS nanosheets through doping and intercalating, the interlayer spacing of 2D SnS nanosheets achieves both expansion (~6.5 %) and compression (~8.0%). More importantly, the samples with various interlayer spacing show distinguishing nitrate reduction efficiency. The SnS nanosheet with compressed interlayer spacing can reach high ammonia Faradaic efficiencies (surpassing 90%) and yield rate (~0.31 mmol cm− 2 h− 1). Different characterize tools are applied to investigate the mechanism, including in-situ Raman spectra and DFT calculations. The results attribute to the variational delocalized electron density of localized p-orbital in Sn, which contribute to the faster conversion of the rate-determining step (*NO3→*NO2) and the higher chemical affinity of NO3 - and NO2 - in eNO3RR, and the suppressed hydrogen evolution reaction in the meantime. Taken together, our work verifies the feasibility of tailoring the interlayer spacing of 2D materials by active diatomic pairs and further implicates interlayer engineering in promoting efficient electrochemical nitrate conversion devices.

Shedding Light on Eu(III) β‐Diketonate Compounds with 1,2‐Bis(diphenylphosphino)ethane Oxide Ligand: an Optical Study

AbstractA series of novel lanthanide β‐diketonate coordination compounds containing the ancillary ligand bis(diphenylphosphino) oxide (dppeO2) have been synthesized, characterized, and studied spectroscopically. The compounds of formulas Ln(β‐dik)3(dppeO2), where Ln: Eu and Gd and β‐dik ligands as tta (Ln‐1), btf (Ln‐2), bzac (Ln‐5) and tfac (Ln‐4), and Ln2(β‐dik)6(dppeO2) with ligand dbm (Ln‐3) and fod (Ln‐6). Their photophysical properties were investigated from the Judd‐Ofelt intensity parameters ( ), radiative ( ) and non‐radiative ( ) rates, intrinsic ( ) and overall ( ) quantum yields, and CIE (x,y) color coordinates. The Eu‐5 and Eu‐6 compounds have the first excited triplet states T1 (around 18802 and 18976 cm−1, respectively) almost resonant with the Eu3+ 5D0 emission level, whereas the complexes Eu‐1, Eu‐2, Eu‐3, and Eu‐4 exhibited higher T1 energies. The values were predominantly driven by the intensity parameter , suggesting more pronounced angular changes in the first coordination sphere of the Eu3+ ion. The values also exhibited significant changes with the β‐diketonate ligands. Eu‐1 showed the highest value of (60 %), indicating a more efficient intramolecular energy transfer process. On the other hand, Eu‐5 and Eu‐6 compounds showed values equal to 18.7 % and 16.5 %, respectively, which indicates the presence of luminescence quencher channels.

The Kondo Effect in CexLaLuScY (x = 0.05-1.0) High-Entropy Alloys.

In the search for electronic phenomena in high-entropy alloys (HEAs) that go beyond the independent-electron description, we have synthesized a series of hexagonal rare earth (RE)-based HEAs: CexLaLuScY (x = 0.05-1.0). The measurements of electrical resistivity, magnetic susceptibility and specific heat have shown that the CexLaLuScY HEAs exhibit the Kondo effect, which is of a single impurity type in the entire range of employed Ce concentrations despite the alloys being classified as dense (concentrated) Kondo systems. A comparison to other known dense Kondo systems has revealed that the Kondo effect in the CexLaLuScY HEAs behaves quite differently from the chemically ordered Kondo lattices but quite similar to the RE-containing magnetic metallic glasses and randomly chemically disordered Kondo lattices of the chemical formula RE1xRE21-xM (with RE1 being magnetic and RE2 being nonmagnetic). The main reason for the similarity between HEAs and the metallic glasses and chemically disordered Kondo lattices appears to be the absence of a periodic 4f sublattice in these systems, which prevents the formation of a coherent state between the 4f-scattering sites in the T→ 0 limit. The crystal-glass duality of HEAs does not bring conceptually new features to the Kondo effect that would not be already present in other disordered dense Kondo systems. This study broadens the classification of HEAs to correlated electron systems.

Electrochemical Investigations of Double Perovskite M2NiMnO6 (Where M = Eu, Gd, Tb) for High-Performance Oxygen Evolution Reaction

Double perovskites are known for their special structures which can be utilized as catalyst electrode materials for electrochemical water splitting to generate carbon-neutral hydrogen energy. In this work, we prepared lanthanide series metal-doped double perovskites at the M site such as M2NiMnO6 (where M = Eu, Gd, Tb) using the solid-state reaction method, and they were investigated for an oxygen evolution reaction (OER) study in an alkaline medium. It is revealed that the catalyst with a configuration of Tb2NiMnO6 has outstanding OER properties such as a low overpotential of 288 mV to achieve a current density of 10 mAcm−2, a lower Tafel slope of 38.76 mVdec−1, and a long cycling stability over 100 h of continuous operation. A-site doping causes an alteration in the oxidation or valence states of the NiMn cations, their porosity, and the oxygen vacancies. This is evidenced in terms of the Mn4+/Mn3+ ratio modifying electronic properties and the surface which facilitates the OER properties of the catalyst. This is discussed using electrochemical impedance spectroscopy (EIS) and electrochemical surface area (ECSA) of the catalysts. The proposed work is promising for the synthesis and utilization of future catalyst electrodes for high-performance electrochemical water splitting.

Colorimetric fluorescence determination of anthrax biomarker using a bimetallic lanthanide metal–organic framework

Bacillus anthracis is toxic bacterial spore that cause human anthrax infections. Therefore, rapid and sensitive detection of Bacillus anthracis or its main biomarker 2, 6-pyridine dicarboxylic acid (DPA) is of great significance. Herein, a series of lanthanide–organic frameworks (Tb/Eu-MOF-1–6) were synthesized by the solvothermal reactions of 2,2′-bipyridine-6,6′-dicarboxylic acid (H2BPDC) with Eu3+ and Tb3+. Among these samples, Tb/Eu-MOF-6 exhibited selective detection of DPA with self-calibrating and colorimetric fluorescence determination. The sensitivity of Tb/Eu-MOF-6 revealed a linear response of ln (IN) = -10.896CDPA + 0.14366 with a limit of detection with 4.51 μM. The emission color of Tb/Eu-MOF-6 observed with the naked eye, turned yellow to red after introducing appropriate concentration of DPA.The energy-transfer behavior between BPDC2- Tb3+, and Eu3+ was systematically studied, which primarily controlled the sensitivity of detection. With the combined merits of self-calibrating, rapid and naked-eye recognition of DPA, Tb/Eu-MOF-6 can be counted as a promising contender for anthrax biomarker detection.

Contrasting rare earth element concentrations and mixing behaviors in the St. Lawrence Estuary and Saguenay Fjord

Rare earth elements (REEs) including Yttrium (Y) are commonly used as tracers of estuarine and oceanic mixing. The lanthanide series and yttrium are usually referred to as REYs. The geochemical behavior of REYs in estuarine environments is generally described as being non-conservative, with large-scale removal by particle scavenging. During mixing, partitioning of these elements occurs according to their source function and the stability of natural complexes, with heavy REEs typically forming more stable complexes than light REEs in solution. In this study, we compare the concentrations and partitioning of the 0.7 μm-filtered and 0.05 μm-filtered fractions of the dissolved REYs collected during the summers of 2017 and 2021 in the surface waters (< 3 m) of the St. Lawrence estuarine system (river, estuary and gulf) with those of the Saguenay Fjord, a tributary of the latter that drains the Mesoproterozoic rocks of the Canadian Shield. Whereas REYs do not mix conservatively in the St. Lawrence Estuary (SLE) in the summer, they nearly do so in the Saguenay Fjord (SF). REY concentrations are 2.5 to 6 times greater in the surface waters of the SF than those of the SLE at the same salinity and, in contrast to most estuaries including the SLE, the fjord waters are enriched in LREEs. The 0.05 μm-filtered REY concentrations are positively correlated with dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) concentrations in the SF but independent of both DOC and CDOM concentrations in the SLE. The CDOM in the fjord differs from that of the estuary as it is more aromatic and has a higher molecular weight. The formation of strong REE-humate complexes stabilizes REY ions in the SF surface waters and impedes their adsorption to and scavenging by solid surfaces during estuarine mixing. The LREE enrichment in the SF surface waters most likely reflects the geology of the fjord's drainage basin, more specifically the exposed Mesoproterozoic granites and gneisses of the Canadian Shield that are enriched in LREE relative to the younger Paleozoic sedimentary rocks exposed along the St. Lawrence Lowlands.

Straw-bundle-like rare earth metal-organic frameworks derivatives for high-efficiency electromagnetic wave absorption

Metal-organic frameworks (MOFs) derivatives have been widely developed as electromagnetic wave (EMW) absorption materials. Nevertheless, owing to the diverse metal ions, organic ligands, and crystal morphologies of MOFs precursors, challenges still remain to overcome towards directly ascertaining the contribution of metal components on EMW absorption for precisely designing high EMW absorption performance of MOF derivatives. Here, we synthesize a series of rare earth (RE) MOF derivatives via a facile, scalable coprecipitation followed by carbonization approach. Thanks to the similar chemical property derived from lanthanide shrinkage of RE elements, the MOF-derived RE oxides (REO)/carbon (REO = CeO2, La2O3, Nd2O3) hybrids exhibit the identical straw-bundle-like microstructure, efficiently assisting the elucidation of the roles of metal components in promoting EMW absorption. Benefiting from the tunable bandgap of various REO as well as carbonization temperature, the 800 °C-carbonized CeO2/carbon shows a minimum reflection loss of − 58.7 dB at a thickness of 1.7 mm and an effective absorption bandwidth of 5.0 GHz, comparable to the best EMW absorbers. This work not only demonstrates novel, high-performance RE-MOF derivatives, but also offers a general yet efficient strategy for designing metal components to achieve high-efficiency MOF-based EMW absorbers.

Sunlight-Driven Photocatalysis for a Set of 3D Metal-Porphyrin Frameworks Based on a Planar Tetracarboxylic Ligand and Lanthanide Ions.

Metal-porphyrin frameworks (MPFs) with trivalent lanthanide ions are the most sought-after materials in the past decade. Their porosities are usually complemented by optical properties imparted by the metal nodes, making them attractive multifunctional materials. Here, we report a novel family of 3D MPFs obtained through solvothermal reactions between tetrakis(4-carboxyphenyl) porphyrin (H4TCPP) and different lanthanide sources, yielding an isostructural family of compounds along the lanthanide series: [Ln2(DMF)(TCPP)1.5] for Ln = La, Ce, Nd, Pr, Er, Y, Tb, Dy, Sm, Eu, Gd, and Tm. Photoluminescent properties of selected phases were explored at room temperature. Also, the photocatalytic performance exhibited by these compounds under sunlight exposure is promising for its implementation in organic pollutant degradation. In order to study the photocatalytic activity of Ln-TCPPs in an aqueous medium, methylene blue (MB) was used as a contaminant model. The efficiency for MB degradation was Sm > Y > Yb > Gd > Er > Eu > either no catalyst or no light, obtaining more than 70% degradation at 120 min with Sm-TCPP. These results open the possibility of using these compounds in optical and optoelectronic devices for water remediation and sensing.

Lanthanide atoms doped arsenene monolayer: Enhanced magnetic anisotropies, huge magnetic moments and significant strain-modulated effects

Employing the spin-polarized density functional theory (DFT), we investigated the magnetic and optical properties of buckled arsenene (β-As) after doping a whole series of lanthanide (Ln) atoms. Our results demonstrate that Ln atoms can be stably doped into the single layer arsenene. Upon doping Ln atoms, La, Ce, Pr, Nd, Gd, Dy and Lu@arsenene behave dilute magnetic semiconductor (DMS) properties, while the Pm, Sm, Eu, Ho, Er and Tm@arsenene show half metallic characteristics. Most of Ln@arsenene systems favor the long-range ferromagnetic ordering. The maximum of Ln-doped systems' magnetic moments and magnetic anisotropy energy (MAE) can reach 8 μB and 7.48 meV, respectively. The doping of Ln atoms into arsenene improves the optical responses in visible and infrared regions. Strain can alter the magnetic coupling between Sm and the neighboring As atoms and reduce the system's magnetic moment. Besides, strain can improve the MAE of these systems, accompanied by the change of the easy magnetization of Sm@arsenene. Furthermore, compressive and tensile strains effectively improve the optical responses in visible and ultraviolet region, respectively. Based on the obtained results, we believe that the Ln@arsenene monolayer has application prospects in photoelectronics and spintronics such as high-density memory devices.

Magnetic structures and properties of new 1:1 MoB-type RCo0.6Ni0.4 and RCo0.5Ni0.5 (R = Tb, Dy, Ho): Structural transition induced by magnetic ordering

The magnetic properties, the crystal and the magnetic structures of the new 1: 1 RCo1−xNix phase formed by R = Tb, Dy and Ho, have been studied for x = 0.4 and 0.5 by means of physical property measurements, neutron and X-ray (from both laboratory and synchrotron) diffraction methods. These compounds crystallize in the tetragonal MoB structure type (tI16, I41/amd) at room temperature, with no ordered arrangement of Co/Ni atoms on the 8e Wyckoff site available for the transition element. Both the lattice parameters a and c (and unit cell volume, Vobs) decrease from Tb to Ho, with a and c following a linear and a quadratic trend, respectively. A magnetic phase transition is detected by heat capacity and magnetization data for TbCo0.6Ni0.4 at about 85 K. Similar transitions appear in DyCo0.6Ni0.4 and HoCo0.6Ni0.4 at 49 K and 27 K, respectively. These TC well follow the de Gennes factor along the lanthanide series. Neutron diffraction shows for the Tb- and Ho-compounds that strongly ferromagnetic structures characterized by a k = 0 magnetic propagation vector are formed on two different rare earth sublattices which are canted to each other. Only in the Tb-containing phases the magnetic transition leads to a symmetry reduction from tetragonal I41/amd to at least monoclinic I2/a. Magnetic symmetry analysis is used to argue that the presence of a magnetic moment component along the original tetragonal axis should be at the origin of this magneto-structural transition in the Tb-compounds with a possible further symmetry lowering.

LANTHANIDE CONTRACTION IN CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID BASED ON CRYSTALLOGRAPHIC DATA: A SHORT REVIEW

The lanthanide (Ln) series has been attracted so much attention not only for its physical properties but also for its applications in organic synthesis and biomedical engineering. In the lanthanide chemistry, lanthanide contraction is a crucial concept meaning the gradual decrease in ionic radii as the atomic number of the Ln series increases. As a prominent chelator, ethylenediaminetetraacetic acid (EDTA) has been well-known to give stable complexes with various metals including Ln ions, resulted in forming (EDTA−4H)4− anion by deprotonation; over 100 kinds of Ln-EDTA complexes have hitherto been synthesized and structurally characterized using X-ray crystallography. While the lanthanide contraction phenomenon has been extensively studied in certain complexes of Ln, systematization on the Ln-EDTA remains inadequate though the chelates of EDTA are commonly used. Thus, this study presents a comprehensive analysis based on the data from the Cambridge Crystallographic Data Centre (CCDC). In mononuclear EDTA complexes X[Ln(EDTA−4H)(H2O)m]·nH2O (X+ = NH4+and its analogues) systematic lanthanide contraction depending on their coordination number are presented except for a few cases. However, in the case of non-mononuclear complexes or coordination polymers, the compositions become more complicated, and a greater variation in atomic bond length occurs, which is unusual for the lanthanide contraction studies in previous research. These varieties are considered to be influenced by different types of counter-cations, inorganic anions, solvent molecules and bridging O atoms from another EDTA anions. This suggests the flexibility and versatility of EDTA as a ligand. Such findings in the Ln-EDTA complexes could potentially provide us further development of a novel function in the future.

Structural determinations of homo and heterodi- or tetra-nuclear lanthanide complexes and their characterization by μ-Squid experiments

Two families of homo- and heterodinuclear complexes are prepared and structurally characterized, thus demonstrating that genuine complexes involving two lanthanide ions closely located in the lanthanide series can be obtained, taking into account a simple rule that necessitates introduction of the better Lewis acid Ln ion (the smallest Ln ion) into the inner coordination site of the main ligand used in this synthesis. In the first family, the presence of a deprotonated orthovanillin ligand (ovan) around the Ln ion positioned in the outer coordination site of the main ligand allows a good isolation of the dinuclear complexes. These complexes behave as SMSs when a Dy ion is coordinated in the outer site but a weak magnetic magnetic Ln-Dy interaction is needed to create a weak magnetic field able to suppress collapsing of the hysteresis loops in zero external applied field at very low temperature. In the second family, the ovan ligand is replaced by a chloride ligand, so that two dinuclear units are linked together by two Cl…HOMe hydrogen bonds to yield tetranuclear complexes that are not SMMs. Eventually these two preparation pathways are expected to give novel and genuine examples of homo or hetero-dinuclear and tetranuclear lanthanide complexes likely to furnish in future coordination complexes useful in quantum computing.

An effect of hydrophobicity of cosurfactant on the growth of cerium tetrafluoride hexagonal nanorods in water-in-oil microemulsion template

This study involves the effect of hydrophobicity of cosurfactants on the formation of cerium tetrafluoride nanoparticles inside the core of water-in-oil microemulsion. To produce the microemulsions, two distinct chain length cosurfactants, 1-butanol (4 carbon atoms) and 1-hexanol (6 carbon atoms) are employed. Dynamic light scattering (DLS) study reveals that, for both types of microemulsion, the synthesis of nanostructures typically occurs in three stages: nucleation phase (around first 15 min), transition phase (30–60 min) and growth phase (60–120 min). Microstructural analysis of Field Emission Scanning Electron Microscopy (FESEM) supports the evolution of hexagonal nanorods. In comparison to reverse micellar media based on 1-hexanol, 1-butanol based reverse micellar media participates in faster reaction. Longer hydrophobic chain length of 1-hexanol enhances the surface film rigidity and produces a well-defined phase boundary, which reduces intermicellar exchange and leads to the evolution of smaller hexagonal nanorods. Therefore, this study may assist the researcher to better understand how cosurfactants influence the growth of nanostructures of lanthanide series metal nanoparticles, using a microemulsion template.

Extendible synthesis of NaLnW2O8∙2H2O (Ln=Sm–Lu, and Y) via one-step hydrothermal reaction: Phase, morphology and luminescence

The Hydrous lanthanide (Ln) double tungstates of NaLnW2O8·2H2O in orthorhombic structure have been directly produced by hydrothermal reaction of Na2WO4 and Ln(NO3)3 at pH=8 for 24 h under 200 °C for the small ions of Ln = Tm–Lu, under 150 °C for the slightly larger lanthanides of Ln = Ho, Y and Er, and under 100 °C for the even larger lanthanides of Sm–Dy. Moreover, NaLnW2O8·2H2O for Ln = Eu–Dy can also be synthesized at a slightly higher reaction pH of 9 at 150 °C, while it was failed for the other members in the lanthanide series of La–Nd even though various efforts were attempted in hydrothermal conditions. On the basis of the crystal structure of NaLnW2O8·2H2O and lanthanide contraction, this outcome conformed well to Pauling rules. Taking Ln = Lu for example, the phase evolution and morphology were studied by the combined techniques of XRD, FE-SEM, IR and TG/DSC. The photoluminescence properties of NaEuW2O8∙2H2O and NaTbW2O8∙2H2O, including excitation/emission, CIE chromaticity, quantum yields, and fluorescence decay were characterized.

Deferasirox Derivatives: Ligands for the Lanthanide Series.

Deferasirox is an FDA-approved iron chelator used in the treatment of iron toxicity. In this work, we report the use of several deferasirox derivatives as lanthanide chelators. Solid-state structural studies of three representative trivalent lanthanide cations, La(III), Eu(III), and Lu(III), revealed the formation of 2:2 complexes in the solid state. A 1:1 stoichiometry dominates in DMSO solution, with Ka values of 472 ± 14, 477 ± 11, and 496 ± 15 M-1 being obtained in the case of these three cations, respectively. Under the conditions of competitive precipitation in the presence of triethylamine, high selectivity (up to 80%) for lutetium(III) was observed in competition with La(III), Ce(III), and Eu(III). Theoretical calculations provided support for the observed selective crystallization.

Solubilities of individual light rare earth sulfates (lanthanum to europium) in water and H2SO4 solutions (neodymium sulfate)

Rare earth elements (REE) are critical commodities with high accessibility risk due to monopolistic practices of suppliers and increased demand. The REE ores generally require aggressive conditions to dissolve the mineral matrix, and sulfuric acid attack is the most economical preferred treatment route. The main challenge to processing REE resources efficiently is the lack of reliable and recent data regarding the solubility of individual REE sulphates in water as a function of temperature. Therefore, solubilities of light REE sulfates (LaEu) were measured for binary REE2(SO4)3–H2O systems from 25 to 95 °C following both heating and cooling approaches. Additionally, solubility isotherms were determined for the ternary system Nd2(SO4)3–H2SO4–H2O system at 25, 55 and 95 °C from 0.05 to 0.5 M H2SO4. It was found that the solubility of light rare earth sulfates decreases with increasing temperature. Within the light REE series, solubilities increase from La to a local maximum for Pr (by one order of magnitude), followed by a sharp decrease to Nd and Sm. The solubility of Nd2(SO4)3 was moderately improved by the presence of H2SO4, as the solubility values increase by up to 30% in 0.5 M H2SO4 compared to the no acid case. This was explained by the formation of soluble sulfate complexes due to increased concentration of SO42− ions in solution. The increase in solubility resulting from sulfuric acid addition was more significant at higher temperatures, although temperature continued to have a negative overall effect. The nature of the saturating solid phases was determined by XRD analysis on samples collected before and after phase change temperature for Ce, Nd, and Pr sulfates, while only solids collected at 25 and 95 °C were analyzed for the compounds known to form a single type of hydrate over the entire temperature range: usually REE2(SO4)3•8H2O except for La2(SO4)3•9H2O.

Assessment of Stoichiometric Autocatalysis across Element Groups.

Autocatalysis has been proposed to play critical roles during abiogenesis. These proposals are at odds with a limited number of known examples of abiotic (and, in particular, inorganic) autocatalytic systems that might reasonably function in a prebiotic environment. In this study, we broadly assess the occurrence of stoichiometries that can support autocatalytic chemical systems through comproportionation. If the product of a comproportionation reaction can be coupled with an auxiliary oxidation or reduction pathway that furnishes a reactant, then a Comproportionation-based Autocatalytic Cycle (CompAC) can exist. Using this strategy, we surveyed the literature published in the past two centuries for reactions that can be organized into CompACs that consume some chemical species as food to synthesize more autocatalysts. 226 CompACs and 44 Broad-sense CompACs were documented, and we found that each of the 18 groups, lanthanoid series, and actinoid series in the periodic table has at least two CompACs. Our findings demonstrate that stoichiometric relationships underpinning abiotic autocatalysis could broadly exist across a range of geochemical and cosmochemical conditions, some of which are substantially different from the modern Earth. Meanwhile, the observation of some autocatalytic systems requires effective spatial or temporal separation between the food chemicals while allowing comproportionation and auxiliary reactions to proceed, which may explain why naturally occurring autocatalytic systems are not frequently observed. The collated CompACs and the conditions in which they might plausibly support complex, "life-like" chemical dynamics can directly aid an expansive assessment of life's origins and provide a compendium of alternative hypotheses concerning false-positive biosignatures.