Electrochemical study of the Eu(III)/Eu(II) system in molten fluoride media

The electrochemical behaviour of the Eu(III)/Eu(II) system was examined in the molten eutectic LiF–CaF₂ on a molybdenum electrode, using cyclic voltammetry, square wave voltammetry and chronopotentiometry. It was observed that EuF₃ is partly reduced into EuF₂ at the operating temperatures (1073–1143 K). The electrochemical study allowed to calculate both the equilibrium constant and the formal standard potential of the Eu(III)/Eu(II) system. The reaction is limited by the diffusion of the species in the solution; their diffusion coefficients were calculated at different temperatures and the values obey Arrhenius’ law. The second system Eu(II)/Eu takes place out of the electrochemical window on an inert molybdenum electrode, which inhibits the extraction of Eu species from the salt on such a substrate.     

Design and intelligent colour regulation of luminescent silk chemically bonded with Eu(III) and Eu(III)/Tb(III)

Design and successful synthesis of a series of novel luminescent silk chemically modified with europium(III) [Eu(III)] and europium(III)/terbium(III) [Eu(III)/Tb(III)] is reported. The modified silk specimens were characterised by infrared spectroscopy, fluorescence spectroscopy, scanning electron microscopy, and evaluated for their colour fastness. The rare earth ions were linked to the silk fibre via chemical bonds with the aid of tetracarboxylic acids used as the bridging ligands. Therefore, the modified silk had excellent luminescent stability and colour fastness to water and sunlight. Based on the blue fluorescence of silk along with the red and green luminescence of Eu(III) and Tb(III), respectively, under ultraviolet irradiation intelligent colour regulation was easily achieved by adjusting either the amount of Eu(III) or the ratio of Eu(III)/Tb(III). The Commission International de l'Eclairage chromaticity co‐ordinates calculated from the emission spectra also confirm the colour changes. Benefiting from the tunable colour and high stability, the modified silk could be an excellent candidate for applications in anti‐counterfeiting and flexible tunable light‐ emitting materials.     

Tuning the valence of 3,3-di(1H-tetrazol-5-yl)pentanedioic acid: Solvothermal synthesis of Eu(III) and bimetallic Eu(III)/Cu(II) compounds

3,3-Di(1H-tetrazol-5-yl)pentanedioic acid (H₄dtzpda) with four acidic hydrogen atoms can display different valence when reacted with different metal ions. Solvothermal reactions of H₄dtapda with Eu(NO₃)₃·6H₂O or Eu(NO₃)₃·6H₂O/Cu(NO₃)₂·6H₂O afford [Eu(Hdtzpda)(H₂O)₄]·4H₂O (1) and [Eu₂Cu(dtzpda)₂(H₂O)₁₀]·6H₂O (2), respectively, where only three acidic hydrogen atoms of H₄dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda^3 − acts as a pentadentate ligand to bridge Eu(III) centers via the oxygen atoms of the carboxylate group while in compound 2, dtzpda^4 − is a hepadentate one via not only the oxygen atoms of the carboxylate group but also the nitrogen atoms of the tetrazole rings. The luminescence properties of the two compounds in the solid state show both intraligand and characteristic peaks of Eu^3 + at room temperature.     

Tetranuclear Eu(III)-Co(II) complex of an N4O4 macrocycle

The reaction of an Eu(III) complex of the protonated form of the macrocyclic Schiff base derived from 1,3-diamino-2-hydroxypropane and 2,6-diformylphenol, [Eu(H₄L)Cl₃], with three equivalents of base results in a mononuclear complex of the triply deprotonated form of the ligand, [Eu(HL)]. The photophysical properties of the [Eu(HL)] complex are discussed on the basis of emission and excitation spectra, as well as of the emission decay times. The [Eu(HL)] complex in a reaction with cobalt(II) chloride gives a heterometallic Eu(III)-Co(II) macrocyclic complex, [EuCo(HL)(CH₃OH)₂Cl]₂Cl₂·4CH₃OH. In the presence of base and an excess of cobalt(II) chloride the starting [Eu(H₄L)Cl₃] complex is converted to a dinuclear Co(II) complex, [Co₂(H₂L)Cl₂(CH₃OH)₂]·1.5CH₃OH.     

Separation of La(III), Eu(III), and Ho(III) with Sorbents Impregnated by Mixtures of Acidic Phosphoryl Podands and Amines in Nitric Acid Solutions

ABSTRACT

The possibility of separation of La(III), Eu(III), and Ho(III) as respective individual representatives of light, medium, and heavy rare earth elements was studied using sorbents impregnated by mixtures of acidic phosphoryl podands derived from diethylene glycol and octyl, dioctyl, and trioctyl amines from nitric acid solutions of various concentrations. The influence of the phosphoryl podands structure, their percentage content, and proportion in a sorbent and the nature of an acid on the efficiency of separation of La(III), Eu(III), Ho(III) was studied. It is shown that the greater is the concentration of HNO₃, the smaller are the separation factors of REEs, and remarkably so. The most efficient separation is achieved with the concentration of HNO₃ not over 0.04 mol/L. The optimal conditions of separation of La(III), Eu(III), and Ho(III) with the developed sorbent were found. Repeated use of the sorbent for the separation of La(III), Eu(III), and Ho(III) after its regeneration with 0.04 mol/L HNO₃ was estimated. It was found that the efficiency of separation of REEs with the sorbents impregnated by a mixture of 1,5-bis(2-oxyethoxyphosphoryl-4-ethylphenoxy)-3-oxapentane and trioctylamine (TOA) exceeds markedly that made of a mixture of di-(2-ethylhexyl)phosphoric acid (DEHPA) and TOA.     

Synthesis and characterization of cellulose ethers/Eu(III)

The coordination complexes of the crystalline structure of cellulose ethers/Eu(III) with fluorescence emission, viz CMC/Eu(III), MC/Eu(III), and HEC/Eu(III), were synthesized and characterized. Results showed the emission spectra of Eu³⁺ ions in these coordination compounds, which originates from electric dipole transition. The main emission peak at 615 nm generated from ⁵D₀→⁷F₂ transition of Eu³⁺ ions. Their absorption and excitation spectra were different, because the effect of the high polarity of water and having both hydrogen bond donor and acceptor properties on the excited molecule is different from the effect on the ground state of the molecule. Our study demonstrated that the Degree of Substitute (DS) of CMC could influence the fluorescence intensity (FI) of CMC/Eu(III). The emission intensity of CMC/Eu(III) varies with the DS of CMC. For example, when the DS of CMC was 0.89, the FS (fluorescent spectra) of solid CMC/Eu(III) displayed three emission peaks Eu(III): the strongest emission peak at 615 nm (⁵D₀→⁷F₂ transition) and other two weaker peaks at 583 nm (⁵D₀→⁷F₁ transition) and at 652 nm (⁵D₀→⁷F₃ transition), respectively. The concentration of Eu(III) could also affect the FI of these coordination complexes. The FI of the coordination complexes peaked at 615 nm all reached maximum when Eu³⁺ concentration was at 5% (wt/wt). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 743–747, 2005     

Photoluminescent Polymer Composites Based on New Tb(III) and Eu(III): Maleimide Complexes

The paper reports the preparation of two photoluminescent polymer composites by embedding two newly prepared Tb(III) and Eu(III) complexes into poly(4-styrenesulfonic acid) matrices using maleimide as ligand. In the first step, the photoluminescent complexes were prepared at 1:3 metal-to-ligand ratio. Prior to the embedment into the polymer matrix the complexes were investigated by chemical and thermal analysis, FT-IR, powder X-ray diffraction and fluorescence spectroscopy. The prepared composites preserve the photoluminescent properties of the complexes and provide them with long-term stability. Thin films of the composites were spin–coated on glass slides and investigated by SEM and AFM techniques. The remarkable photoluminescent properties of the composites prepared in bulk or deposited in thin films on various substrates recommend them for applications in optical devices as photonic conversion mediums.     

Study on interaction between Eu(III) and thermosensitive microsphere

Based on the synthesis of poly(N-isopropylacrylamide)-grafted poly(N-isopropylacrylamide-co-styrene) (PNNS) microsphere, Eu(III) was chosen to coordinate with PNNS. The interaction between Eu(III) and PNNS was characterized by using X-ray photoelectron spectroscopy, Fourier transform infrared, ultraviolet–visual and fluorescence spectroscopy. The results from experiments indicated that the Eu(III) is mainly bonded to O of the carbonyl groups of PNNS and formed the complex of PNNS–Eu(III). After forming the PNNS–Eu(III) complex, the emission fluorescence intensity of Eu(III) in the complex is significantly enhanced because the effective intramolecular energy-transfer from PNNS to Eu(III). Especially, the maximum emission intensity of the PNNS–Eu(III) complex at 614 nm is enhanced about 33 times comparing to that of the pure Eu(III). The intramolecular energy-transfer efficiency from PNNS to Eu(III) reaches 55%.     

Screening of ATP hydrolysis by Zr(IV) and Eu(III) complexes

The dephosphorylation of adenosine triphosphate (ATP) by various zirconium (IV) and europium (III) complexes is described. Release of phosphate was followed by an automated, robotics-based colorimetric assay which is compatible with the presence of these high-valent metal ions.     

影像科学与光化学(原名感光科学与光化学)

本刊主要刊登影像科学和光化学领域的研究成果,同时刊登有关信息科学及信息材料,包括信息储存和记录、信息的处理和加工及信息显示材料等;光/电化学及光电子技术,包括光/电转换及储存材料、电光材料、非线性光学材料、纳米材料、电致发光材料及器件研究以及化学和物理发光等领域;光生物,光医学及生命科学与环境科学中的有关问题的新理论、新概念、新技术和新方法,以促进国内外的学术交流.     

Complexation of Eu(III) with Dibutyl Phosphate and Tributyl Phosphate

Abstract

The complexation of Ln(III) with tributyl phosphate (TBP) in the presence of dibutyl phosphate (HDBP) is of importance for the smooth operation of the plutonium uranium refining extraction (PUREX) process. The time resolved laser‐induced fluorescence spectroscopy (TRLFS) and extraction experiments were employed to study the complexation of Eu(III) with TBP or HDBP and their mixture. The emphasis was on the inner‐sphere hydration numbers and emission spectra of the Eu(III) extracted complexes. The results show that the HNO₃ loading in the organic phase influences not only the distribution ratio but also the emission spectra, as well as the hydration numbers of the complexes. For the Eu‐TBP complexes, one water molecule remained at low HNO₃ loading in the organic phase, and it would be removed at enhanced HNO₃ loading. For the Eu‐HDBP complexes, one water molecule remained at low or high HNO₃ loading. For the Eu‐HDBP/TBP or Eu‐HDBP/30%TBP, more than one species formed and third phase with different chemical form appeared at low HNO₃ loading. The possible species of Eu(III) complexes formed under various conditions were proposed and discussed.     

Adsorption behavior of Eu(III) on partially Fe(III)- or Ti(IV)-coated silica

The adsorption behavior of Eu(III) onto silica surface, which was partially coated with Fe(III) or Ti(IV), was investigated to determine Fe(III) or Ti(IV) effects on the surface reaction of lanthanides on mineral surfaces in groundwater. Compared with a parallel uncoated silica, the Fe(III)-coated silica did not enhance the adsorption of Eu(III). However, enhanced adsorption of Eu(III) on the Ti(IV)-coated silica was observed by increasing the amount of Ti(IV) on the silica surface.     

Extraction behavior of Am(III) and Eu(III) by tri-n-octylmethylammonium diglycolamate ionic liquid impregnated XAD-7

Aliquat-336-based strongly hydrophobic ionic liquid, tri-n-octylmethylammonium diglycolamate ([A336]⁺[DGA]^?), was prepared and impregnated in Amberlite XAD-7 (abbreviated as [A336]⁺[DGA]^?/XAD-7) for studying the extraction behavior of Am(III) and Eu(III) from nitric acid medium. The distribution ratio of Am(III) and Eu(III) in [A336]⁺[DGA]^?/XAD-7 decreased with an increase in the concentration of nitric acid and the mechanism of trivalent metal ion extraction in the resin phase was elucidated. The uptake of Am(III) and Eu(III) in [A336]⁺[DGA]^?/XAD-7 followed a second order and from the Langmuir adsorption model the apparent europium extraction capacity was determined. The conditions needed for efficient separation of Am(III) from Eu(III) was optimized.     

Photochemistry and Structure of Metal Amine Solutions

The photochemistry of the 670 nm band in fluid sodium amine solutions is investigated by applying flash (optical detection) or steady state (ESR detection) irradiation techniques. The photoregeneration of faded alkali metal solutions induced by exciting the amide decomposition product, is also submitted to flash investigation. In both cases the primary act appears to be the generation of solvated electrons. The available photochemical data are examined in light of a recent spectroscopic study which attributes the 670 nm band to a sodium anion (Na^?) and the 850, 920 and 1030 metal bands to K^?. Rb^? and Cs^?, respectively. It is concluded that the photochemical observations provide new evidence for the model involving the alkali metals negative ions. Electron photoejection in a rigid amine glass at ?196°C produces a (IR) band which is red shifted relative to that present in an equilibrium liquid solution, frozen to the same low temperature glass. The effect is attributed to two, physically distinguishable, solvated electrons in glasses or, alternatively, to an additional (unidentified) IR species present in the dark equilibrium solutions.     

Solvent extraction kinetics of Sm(Ⅲ),Eu(Ⅲ) and Gd(Ⅲ) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester

Solvent extraction kinetics of Sm(Ⅲ), Eu(Ⅲ) and Gd(Ⅲ) from hydrochloric acid have been focused on using2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507) with Anordning for Kontinuerlig Undersokning av Fordelningsfaktore vid Vatske Extraction(AKUFVE). Compared with the conventional set-up, some advantages emerge obviously, for example, fast phase separation, easy operation and convenience of kinetic data acquisition.First of all, the extraction mechanism was discussed based on the dimeric model of P507. Secondly, the effects of stirring speed were investigated and 420 r·min~(-1) was determined of the following experiments. The effects of pH, concentration of rare earth elements(REEs) and P507 on the extraction rate were analyzed. The results indicated that the extraction mechanism changed with the increasing concentration of P507. Then, the experiments with different temperature were carried out. It turned out that the values of apparent activation energy(E_a) for Sm(Ⅲ), Eu(Ⅲ) and Gd(Ⅲ) extracted by P507 were 26.80 kJ·mol~(-1), 13.40 kJ·mol~(-1) and11.10 kJ·mol~(-1) respectively, the resistance of the entire process was limited by diffusion or both of diffusion and reaction. Finally, the correlation equations were obtained, and the theoretical results fit with the experimental data well, most relative error was within ±30%.     

Spectroscopic Comparison of Eu(III) Binding to Various Biosorbents

Biosorption of Eu(III) to various biogenic materials was investigated using luminescence spectroscopy involving excitation of non-degenerate ⁷F₀ → ⁵D₀ transition of bound metal ions. Materials included cultured anther cell fragments from Datura innoxia, pecan shells (Protandrous spp.), dried bean sprouts (vigna spp.), and dried tissues from the roots, stems, and leaves of mature tumbleweeds (Salsola spp.), non-viable algae cells of Chlorella vulgaris immobilized within a polysilicate matrix, sphagnum peat, dried peat, and a commercially available organic peat material. Analysis of resulting excitation spectra indicated only minimal variation in binding environments for the different tumbleweed tissues when respective spectra were visually compared. Observed red-shifts in excitation spectral envelopes suggest an increased stabilization of surface ligand-metal associations for all materials compared to D. innoixia. Application of principal component analysis to these spectra resulted in segregation of materials using a model accounting for 89.48% of the variance using three principal components. This analysis revealed similarities among the spectra from the roots and stems of the tumbleweeds along with that from the bean sprout sample. The model confirmed differences in metal binding to the D. innoxia materials. It also indicated significant differences in metal ion binding to the organic peat and Chlorella-based biosorbents.