Rare Earth Metals Europium Research Articles

Constructing Self-Healing Polydimethylsiloxane through Molecular Structure Design and Metal Ion Bonding.

Self-healing polydimethylsiloxane (PDMS) has garnered significant attention due to its potential applications across various fields. In this study, a functionalized modification of PDMS containing di-aminos was initially conducted using 2,6-pyridinedicarbonyl chloride to synthesize pyridine-PDMS (Py-PDMS). Subsequently, rare earth metal europium ions (Eu3+) were incorporated into Py-PDMS. Due to the coordination interaction between Eu3+ and organic ligands, a coordination cross-linking network was created within the Py-PDMS matrix, resulting in the fabrication of Eu3+-Py-PDMS elastomer. At a molar ratio of Eu3+ to ligands of 1:1, the tensile strength of Eu3+-Py-PDMS reached 1.4 MPa, with a fracture elongation of 824%. Due to the dynamic reversibility of coordination bonds, Eu3+-Py-PDMS with a metal-to-ligand molar ratio of 1:2 exhibited varying self-healing efficiencies at different temperatures. Notably, after 4 h of repair at 60 °C, its self-healing efficiency reached nearly 100%. Furthermore, the gas barrier properties of Eu3+-Py-PDMS with a molar ratio of 1:1 was improved compared with that of Eu3+-Py-PDMS with a molar ratio of 1:1. This study provides an effective strategy for the design and fabrication of PDMS with high mechanical strength, high gas barrier properties, and exceptional self-healing efficiency.

Discrepancies in Solvent Extraction Slope Analysis Caused by Aqueous Buffer Complexation

ABSTRACT The interaction between an aqueous phthalate buffer and the rare earth metal europium(III) was investigated to demonstrate the effect of buffer complexation of Eu on solvent extraction slope analysis. Some literature has suggested the formation of aqueous rare earth-hydroxide complexes in solvent extraction systems due to depressed slopes in log–log plots of extraction data. These claims were made despite the experiments being conducted under acidic conditions where extraction of rare earth-hydroxide complexes cannot affect the acid dependence of the extraction, and despite neglecting to account for aqueous buffer ligand complexation. We investigated the extractant concentration and acid dependencies of the Eu distribution ratio for two bis(2-ethylhexyl)phosphoric acid/o-xylene extraction systems with varying aqueous phase compositions. The first system contained no buffer and produced log–log plots with slopes close to 3, while the second system containing aqueous phthalate buffer resulted in greatly diminished distribution ratio values and acid dependencies with variable slopes. These experiments, in conjunction with fluorescence spectroscopy of the aqueous phases, suggest that the rare earth elements complex with aqueous buffer rather than hydroxide at pH values less than 6.

Ultraviolet and X-ray photoelectron spectra and the electronic structure of Eu(III) and Lu(III) β-diketonate complexes

Ultraviolet (UV) and X-ray photoelectron spectroscopy and quantum chemistry methods (DFT) are used to study tris-β-diketonates of the rare-earth metals europium and lutetium. New information is obtained on the electronic structure of the complexes. The geometric and electronic structures of the compounds are calculated. The nature of chemical bonding in the compounds is analyzed. The quantum-chemical studies reveal patterns in the variations of the electronic structure, which depend on the complexing agent, and determine the effects of the substitution of C(CH)3 and CF3 for CH3-groups in the ligands. Band identification is obtained for the UV (in the gaseous phase) and X-ray photoelectron (in the condensed state) spectra of Eu and Lu tris-dibenzoylmetanates.

Preparation and Spectral Analysis of Light Conversion Advanced Invisible Falsification-Resistant Ink

This paper discusses the structure design, light conversion agents, vehicles, colorants and the selection of other functional additives of light conversion advanced invisible falsification- resistant ink, the preparation of the light conversion falsification-resistant ink and rare earth metal europium complex, and analyzes rare earth metal europium complex, Eu(C5H7O2)3C12H8N2, through infrared spectrometer, element analyzer and fluorescence spectrometer. The results of the above analysis identify the composition of rare earth metal europium complex, its excitation spectrum ranging from 200nm to 400nm, and its emission spectrum ranging from 580nm to 640nm. Experiments suggest when the mixture of rare earth metal europium complex and white ink with titanium dioxide in a fixed proportion is printed on any objects, it appears reddish orange light under ultraviolet irradiation, which achieves the advanced invisible anti-counterfeiting effect.

The 1-N amides 1 ∞[Eu2(Pyr)4(PyrH)2(NH3)] · PyrH and [Yb2(Cbz)4(NH2)2(NH3)4] · 3CbzH: Distinctions in the crystal structures, thermal properties and ammonolysis tendency

Abstract The low-temperature oxidation of the rare earth metals europium and ytterbium with the 1-N amines pyrrole and carbazole in liquid ammonia gave the pyrrolate 1 ∞[Eu2(Pyr)4(PyrH)2(NH3)] · PyrH (1) (Pyr – = C4H4N–, pyrrolate anion; PyrH = C4H4NH, pyrrole) and the carbazolate [Yb2(Cbz)4(NH2)2(NH3)4] · 3CbzH (2) (Cbz – = C12H8N–, carbazolate; CbzH = C12H8NH), respectively. Though both compounds are ammine complexes, the course through the redox potentials ELn(II/III) as well as the growing steric demand of the ligand result in various differences in the properties of the products. 1 shows a 1-dimensional structure of pyrrolate, pyrrole groups and one equivalent of ammonia coordinating and bridging divalent europium centers. This includes η 5 – π-interactions between the metal centers and pyrrolate and pyrrole rings. The resulting polymer shows a rather high thermal stability and melts at 445 °C prior to decomposition under release of ammonia at 475 °C. Contrary to this, 2 contains dimeric units around trivalent ytterbium consisting of carbazolate, ammonia and NH– 2 amide groups. No π-interactions are observed. Instead ammonolysis of liquid ammonia results in formation of an amide that contains two different amide groups. The thermal stability of 2 is lower than of 1. The building units of complex 2 decompose at 310 °C without melting. Both compounds were investigated by low-temperature single crystal X-ray analysis, Mid IR, Far IR and Raman spectroscopy as well as simultaneous DTA/TG.

Time-resolved fluorometric assay for the detection of endostatin in chromatographically separated extracts of natural peptides

We present a heterogeneous non-competitive immunological detection assay for peptide and protein antigens from crude extracts of biological sources. This time-resolved fluoroimmunoassay (TR-FIA) has been designed in a solid-phase mode using 96-well microtiter plates. Using the rare-earth metal europium as a fluorescent marker, a highly sensitive, selective and efficient procedure was developed. This technique prevents from interferences of intrinsic protein fluorescence which is highly important for antigen measurement in complex matrices. The TR-FIA has been applied for the detection of circulating forms of the potential anti-tumor agent endostatin, a C-terminal fragment of collagen XVIII, and its close homolog collagen XV (restin) from hemofiltrate. Endostatin was detected with a limit of detection of 3 ng (150 fmol/well) and a broad dynamic range from 10–1000 ng/well.

Formation of Crystal Film at Interface in Process of Extraction of Rare Earth Metals by D2EHPA.

In the process of extraction of the rare earth metals europium and samarium by D2EHPA, we find that solid films form at the organic/aqueous interface. For extraction solution systems of europium and samarium, we specified concentration zones where the solid films should form, and show that the formation of the solid films occurs at the specific zones of hydrogen ion and extractant concentrations. We also determine the atomic constituents of the solid films by inductively coupled plasma emission spectroscopy, and find that the solid films are crystals composed of neutral 1:3 intermediate complexes. We further investigate film formation in the extraction solution system that contains two lanthanide elements, europium and samarium. We determine the atomic ratio of the solid film, and show that the atomic ratio takes the value which is near to that predicted from the separation coefficient in the organic/aqueous solution system.

The generalised susceptibility and joint density of states of BCC europium

It is well known that the rare-earth metal europium has helical spin ordering below the Neel temperature TN=91K. By using the tetrahedron method, the authors have calculated the generalised magnetic susceptibility chi (q) under the constant matrix element approximation from their self-consistent (SCF) band calculations, and they have made clear the relation between chi (q) and the nesting of the Fermi surfaces. The chi (q) curve they obtain has a maximum at mod q mod =0.36(2 pi /a). This shows very good agreement with the incommensurate period of the helix of Nereson's experimental results (1964). They have also calculated the interband joint density of states (JDOS). The JDOS curve shows that the first three maximum peaks occur at 1.54, 1.87 and 2.25 eV, which is in excellent agreement with the experimental results of Endriz and Spicer (1970).

Time-resolved fluoroimmunoassay: a new test for rubella antibodies.

A new solid-phase immunoassay, time-resolved fluoroimmunoassay (TR-FIA), for rubella antibody was developed. The test used polystyrene beads coated with rubella antigen as the solid phase and a chelate of the rare earth metal europium as fluorescent label. A fast light pulse from a xenon flash lamp was used to excite the label, and after a 400-mus delay time the emission fluorescence was measured for 500-mus at 1-ms intervals during a total counting time of 1 s. Background fluorescence of short duration caused by fluorescent serum components and scattering could be eliminated by including the delay time. The TR-FIA was compared with hemagglutination inhibition, single radial hemolysis, and two types of radioimmunoassay (RIA) (a commercial RIA [GammaCoat] and a noncommercial RIA [T-RIA]) by using 60 serum specimens from patients with remote rubella infection. Overall agreement of TR-FIA with hemagglutination inhibition and GammaCoat was 96.7%, with single radial hemolysis 98.3%, and with T-RIA 100%. Linear regression coefficients varied from 0.83 to 0.94, the best being obtained with single radial hemolysis and T-RIA. TR-FIA was also found to be suitable for the diagnosis of acute infections, as significant increases of antibody level were detected in all 30 paired serum specimens tested from patients with an acute rubella infection. Sensitivity and specificity comparable to those of RIA and enzyme immunoassay were obtained with TR-FIA. Furthermore, the advantage that TR-FIA has over RIA is that it incorporates a nonisotopic and stable label; its advantage over EIA is that it is easier to standardize because no additional reaction with substrate is required.

Reflectance Studies of Ba, Sr, Eu, and Yb

In situ reflectance measurements have been made on films of the alkaline-earth metals barium (bcc) and strontium (fcc), and rare-earth metals europium (bcc) and ytterbium (fcc) from 1.0 to 11.6 eV. Extreme care was taken in all aspects of the work so that a Kramers-Kr\"onig analysis of the reflectance data yielded optical constants ${\ensuremath{\epsilon}}_{1}$, ${\ensuremath{\epsilon}}_{2}$, $\ensuremath{\sigma}$, and $\ensuremath{\alpha}$ which were accurate to better than \ifmmode\pm\else\textpm\fi{} 20%. The volume-loss functions calculated from these optical constants yielded an agreement with loss-function peak positions obtained in Kunz's high-energy electron-loss experiments which was not seen in previous optical studies, and served as verification of the improved accuracy of the present study. A comparison of the interband optical conductivities for the alkaline-earth and rare-earth metals failed to indicate strong structure or increased oscillator strength in the rare-earth metals which could be unambiguously attributed to transitions from $4f$ electrons found in europium and ytterbium. The filled $4f$-electron states in these two metals are known to be accessible to the spectral range of the present study, and an explanation, based on matrix elements, is proposed for this inability to excite such electrons. The structure which was observed in the interband conductivity of all four of these metals was correlated to crystal structure and showed much better agreement with the predictions of strong $d$-electron effects implied in recent band calculations than it did with the simple predictions of the nearly-free-electron theory.