Self-assembly of lanthanide mixed-carboxylates coordination polymers

Two new mixed-ligands lanthanide coordination polymers, [Ln(Ac)(ip)(H₂O)₂]·0.5H₂O (Ln=La (1); Ln=Eu (2); Ac=acetate; ip=isophthalate) have been synthesized under hydrothermal condition. Single-crystal X-ray analyses show that complexes 1 and 2 are three-dimensional structure in which lanthanide ions are bridged by monocarboxylate ligand, acetate or dicarboxylate ligand, isophthalate. And the central lanthanide ions, La³⁺ and Eu³⁺, are both nine-coordinate with oxygen atoms. The thermogravimetric analysis was carried out to examine the thermal stability of the title complexes. And the photoluminescence property of complex 2 was also investigated.     

Trivalent lanthanide metal ions promote formation of stacking G-quartets

We report the first examples of stacking G-quartet formation assisted by trivalent lanthanide metal ions (La3+, Eu3+, Tb3+, Dy3+, Tm3+).     

Luminescence behavior of Eu3+ doped LaF3 nanoparticles

Europium-doped LaF3 nanoparticles have been prepared by the ionic reaction in the ethanol at 60 degrees C. From the XRD pattern of nanoparticles and the emission spectra of Eu3+ ions, it has been concluded that the Eu3+ ions could easily substitute the La3+ sites and the solid solution La(1-x)Eu(x)F3 can be synthesized. Due to very low phonon energies of LaF3 matrix, the 5D1 emission of Eu3+ ions in La(1-x)Eu(x)F3 nanoparticles can be observed at room temperature when doping concentration of Eu3+ ions is lower than 30 mol%. The quenching process of 5D1 emission can be attributed to cross-relaxation. Since clusters of Eu3+ ions and resonance energy transfer only occurs within one particle due to the hindrance by the particle boundary, the concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurs at higher Eu3+ concentrations in the Eu3+ doped LaF3 nanoparticles.     

The Effects of Trivalent Lanthanide Cationization on the Electron Transfer Dissociation of Acidic Fibrinopeptide B and its Analogs

Electrospray ionization (ESI) on mixtures of acidic fibrinopeptide B and two peptide analogs with trivalent lanthanide salts generates [M + Met + H]⁴⁺, [M + Met]³⁺, and [M + Met –H]²⁺, where M = peptide and Met = metal (except radioactive promethium). These ions undergo extensive and highly efficient electron transfer dissociation (ETD) to form metallated and non-metallated c- and z-ions. All metal adducted product ions contain at least two acidic sites, which suggest attachment of the lanthanide cation at the side chains of one or more acidic residues. The three peptides undergo similar fragmentation. ETD on [M + Met + H]⁴⁺ leads to cleavage at every residue; the presence of both a metal ion and an extra proton is very effective in promoting sequence-informative fragmentation. Backbone dissociation of [M + Met]³⁺ is also extensive, although cleavage does not always occur between adjacent glutamic acid residues. For [M + Met – H ]²⁺, a more limited range of product ions form. All lanthanide metal peptide complexes display similar fragmentation except for europium (Eu). ETD on [M + Eu – H]²⁺ and [M + Eu]³⁺ yields a limited amount of peptide backbone cleavage; however, [M + Eu + H]⁴⁺ dissociates extensively with cleavage at every residue. With the exception of the results for Eu(III), metallated peptide ion formation by ESI, ETD fragmentation efficiencies, and product ion formation are unaffected by the identity of the lanthanide cation. Adduction with trivalent lanthanide metal ions is a promising tool for sequence analysis of acidic peptides by ETD.

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Geometric and electronic structure of lanthanide orthophosphate nanoparticles determined with X-rays

The evolution of the geometric and electronic structures within the entire series of lanthanide orthophosphate nanoparticles ( approximately 2- approximately 5 nm) has been determined experimentally with X-ray diffraction and near edge X-ray absorption fine structure spectroscopy. In particular, the interplay between electronic structure, crystal morphology, and crystal phase has been systematically studied. A missing local order in the crystal structure accompanied by multiple ion sites in the nanoparticles was revealed to be due to the small crystal size and large surface contribution. All lanthanide ions were found to be in "3+" configuration and accommodated in three different crystallization states: the larger lanthanide ions (La, Ce, Pr, Nd, Sm) in the monoclinic phase, the smaller ones (Er, Tm, Yb, Lu) in the tetragonal phase, and the intermediate lanthanide ions (Eu, Gd, Tb, Dy, Ho) in a "mixed phase" between monoclinic and tetragonal phases.     

稀土离子对钙调蛋白与单克隆抗体分子识别的影响

分别采用酶联免疫吸附(ELISA)法和荧光标记技术比较了Ca²⁺,La³⁺,Eu³⁺和Yb³⁺离子对钙调蛋白与单克隆抗体2C3之间分子识别的影响.结果表明,金属离子与钙调蛋白作用后会诱导其发生不同的构象变化,并进一步影响到钙调蛋白与单克隆抗体2C3分子之间的结合强度.当钙调蛋白分别与La³⁺,Eu³⁺,Yb³⁺作用后,它与单抗2C3分子之间的解离常数为(26.8±2.5),(21.8±3.4)和(64.8±5.1)nmol/L,而结合Ca²⁺前后的钙调蛋白与单抗分子的解离常数分别为(177.2±2.8)和(157±4.2)nmol/L.这一结果表明,稀土离子诱导钙调蛋白发生的构象变化明显不同于钙离子的作用,这种差异可能是稀土与钙离子对钙调蛋白调控作用表现出差别的原因.     

稀土与邻香兰素二胺类双Schiff碱配合物合成及其性质的研究

在非水体系中首次合成了硝酸稀土(III)的邻香兰素(2-羟基-3-甲氧基苯甲醛)与乙二胺(L^1)、联苯胺(L^2)、邻苯二胺(L^3)和间苯二胺(L^4)的双Schiff碱配合物(1-8)。通过测定红外光谱、摩尔电导、X射线衍射和X射线光电子能谱推断了配合物的结构和键合情况,配合物的中心金属离子与配体中的二个氮原子、二个氧原子和二个硝酸根中的四个氧原子配位,其配位数为8。通过热重及差热分析发现配合物在低于230℃时很稳定,对于同一配体与不同中心金属离子形成的配合物来说,其热稳定性随稀土离子半径的减小而降低。在77K时测试了铕配合物的激发光谱和荧光光谱,观察到Eu^3^+的特征发射峰。     

Effects of Lanthanide Ions on Electrooxidation of Methanol

Four kinds of lanthanide ions（Sm^3＋,Yb^3＋,Eu^3＋,La^3＋）as an additive were added into the aqueous solution containing methanol,respectively,and their effects on methanol elecotrooxidation in aqueous solutions were studied with cyclic voltammetry.The results show that the four kinds of ions have promotion action upon the electrooxidation of methanol to different degrees.The best additive,Sm^3＋,can increase the anodic oxidation current of methanol by 80%and the peak potential shifted negatively about 50 mV.The promotion effects of the lanthanide ions were considered to be related to the extranuclear electron distribution of these ions and their adsorption on the Pt electrode surface.     

Mono and trinuclear lanthanide complexes of 13-membered tetraaza macrocycle: Synthesis and characterization

The reaction of 1,8-diamino-3,6-diazaoctane and diethyl malonate in dry methanol yielded a 13-membered macrocycle. Complexes of the type [Ln(tatd)Cl₂ (H₂O)₃]Cl [Ln^III=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy; tatd=1, 5, 8, 11-tetra-azacyclotridecane-2,4-dione] have been synthesized by template condensation. The complex [La(tatd)Cl₂ (H₂O)₃]Cl in methanol was reacted with lanthanide chlorides to yield the trinuclear complexes of type [2{La(tatd)Cl₂(H₂O)₃}LnCl₃]Cl₂ [Ln^III=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy]. The chemical compositions of mono and trinuclear complexes have been established on the basis of analytical, molar conductance, electrospray (ES) and fast atom bombardment (FAB) mass data. In mononuclear complexes the Ln³⁺ ion is encapsulated by four ring nitrogens and in trimetallic complexes the exo-carbonyl oxygens of two mononuclear units coordinate to the Ln³⁺ ions resulting in a polyhedron around the lanthanide ions. Thus the macrocycle is bonded in a tetradentate fashion in the former complexes and hexadentate in the latter. The coordination number nine around the encapsulated Ln³⁺ and seven around the exo-oxygen bonded Ln³⁺ ions are established. The symmetry of the ligand field around the metal ions is indicated from the emission spectra.     

稀土有机配合物电致发光研究进展

稀土配合物发射带窄, 发射光谱具有类原子光谱性质, 色纯度高(半宽峰<10 nm), 非常适合于全彩色显示. 另外, 稀土配合物发光效率高, 理论上内量子效率可达100%. 因此, 稀土配合物是全色平板显示器件中理想的发光材料之一, 研究稀土配合物电致发光性质具有重要的实际意义和理论意义. 以稀土镧系离子配合物作为发光中心的电致发光器件的研究主要集中于发光效率比较高的Eu3+, Tb3+ 以及近红外的Nd3+, Yb3+和Er3+ 离子. 分类综述了近年稀土配合物电致发光研究的成果及其进展. 总结了不同类型的铕配合物、铽配合物的电致发光特性, 证明配体对于稀土离子的敏化作用非常重要; 总结了近红外的镱、钕、铒配合物在光放大、激光技术、生物医学等方面的潜在应用价值.     

Optical spectroscopy study of organic-phase lanthanide complexes in the TALSPEAK separations process

Time-resolved fluorescence spectroscopy and Fourier transform IR spectroscopy have been applied to characterize the coordination environment of lipophilic complexes of Eu(3+) with bis(2-ethylhexyl)phosphoric acid (HDEHP) and (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (HEH[EHP]) in 1,4-diisopropylbenzene (DIPB). The primary focus is on understanding the role of lactate (HL) in lanthanide partitioning into DIPB solutions of HDEHP or HEH[EHP] as it is employed in the TALSPEAK solvent extraction process for lanthanide separations from trivalent actinides. The broader purpose of this study is to characterize the changes that can occur in the coordination environment of lanthanide ions as metal-ion concentrations increase in nonpolar media. The optical spectroscopy studies reported here complement an earlier investigation of similar solutions using NMR spectroscopy and electrospray ionization mass spectrometry. Emission spectra of Eu(3+) complexes with HDEHP/HEH[EHP] demonstrate that, as long as the Eu(3+) concentration is maintained well below saturation of the organic extractant solution, the Eu(3+) coordination environment remains constant as both [HL](org) and [H(2)O](org) are increased. If the total organic-phase lanthanide concentration is increased (by extraction of moderate amounts of La(3+)), the (5)D(0) → (7)F(1) transition singlet splits into a doublet with a notable increase in the intensity of both (5)D(0) → (7)F(1) and (5)D(0) → (7)F(2) electronic transitions. The increased multiplicity in the emission spectra indicates that Eu(3+) ions are present in multiple coordination environments. The increased emission intensity of the 614 nm band implies an overall reduction in symmetry of the extracted Eu(3+) complex in the presence of macroscopic La(3+). Although [H(2)O](org) increases to above 1 M at high [HL](tot), this water is not associated with the Eu(3+) metal center. IR spectroscopy results confirm a direct Ln(3+)-lactate interaction at high concentrations of lanthanide and lactate in the extractant phase. At low organic-phase lanthanide concentrations, the predominant complex is almost certainly the well-known Ln(DEHP·HDEHP)(3). As lanthanide concentrations in the organic phase increase, mixed-ligand complexes with the general stoichiometry Ln(L)(n)(DEHP)(3-n) or Ln(L)(n)(DEHP·HDEHP)(3-n) become the dominant species.     

Studies on the extraction and separation of lanthanide ions with a synergistic extraction system combined with 1,4,10,13-tetrathia-7,16-diazacyclooctadecane and lauric acid

1,4,10,13-Tetrathia-7,16-diazacyclooctadecane (ATCO) and its binary extraction system containing lauric acid were studied extensively as extractants of lanthanide (M(3+)=La(3+), Ce(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+) and Gd(3+)) in 1,2-dichloroethane solution. The percentage extraction of Ce(3+) and Eu(3+) by ATCO were only measured to be less than 5% during a pH range 5.5-7.0 in NCS(-), ClO(4)(-) and PF(6)(-) mediums respectively, which indicates that ATCO alone has very low extractability to lanthanide, due to the bad fit of metal ions in its cavity. However, when lauric acid was added to the ATCO organic phase, because of forming rare earth adduct, the percentage extraction for lanthanide until Gd(3+) was enhanced in the binary system in comparison with that did not adopt the lauric acid within the pH range 6-7. The extraction species and extraction equilibrium constants logK(ex) were found to be CeLA(3)3HA, -8.5, EuLA(3)HA, -6.7, and GdLA(2)NO(3)2HA, -1.8, respectively. The separation factor between Eu(3+) and Ce(3+) was found to be 2.5, however, poor selectivity for lanthanide was observed. From Gd(3+) to Er(3+) and Lu(3+), the synergistic effect of the binary extraction system decreases with increasing atomic number. For gadolinium, the synergistic effect becomes much weaker than that of Ce(3+) and Eu(3+), no synergistic effect existed for erbium and lutetium. Thermodynamic data for synergistic solvent extraction are also reported in this paper. The order of organic phase stability constants of the extraction species is Sm (5.8)>Pr (5.7)>Eu (5.6)>Ce (5.3)>La (5.2)>Gd (2.8).     

Eu3+或Tb3+掺杂的KY2F7纳米球的制备与表征

利用简单的室温液相反应制备了KY₂F₇及镧系离子掺杂的KY₂F₇∶Eu³⁺和KY₂F₇∶Tb³⁺的纳米球，并利用XRD，TEM，SEM，XRF和荧光光谱对所制备的材料进行了表征。研究表明Eu³⁺或Tb³⁺离子已成功地掺杂在KY₂F₇纳米球中。掺杂     

Study of lanthanide complexes with salicylic acid by photoacoustic and fluorescence spectroscopy

Solid complexes Ln(Sal)3.H2O (Sal: salicylic acid; Ln: La3+, Nd3+, Eu3+, Tb3+) are synthesized, and their photoacoustic (PA) spectra in the UV-Vis region have been recorded. PA intensities of central lanthanide ions are interpreted in terms of the probability of nonradiative transitions. It is found that PA intensity of the ligand increases in the order of Tb(Sal)3.H2O < La(Sal3).H2O < Eu(Sal)3.H2O < Nd(Sal)3.H2O. Different PA intensities of the ligand are interpreted by comparison with the fluorescence spectra. Ternary complexes Eu(Sal)3Phen and Tb(Sal)3Phen (Phen: 1,10-phenanthroline) are synthesized. Compared with their binary complexes, PA intensity of the ligand Sal decreases for Eu(Sal)3Phen, while the reverse is true for that of Tb(Sal)3Phen. The luminescence of Eu3+ increases remarkably when Phen is introduced, and luminescence of Tb3+ decreases greatly when Phen is added. The intramolecular energy transfer and relaxation processes in the complexes are discussed from two aspects: radiative and nonradiative relaxations.     

The Studies of Lanthanide Shift Reagents in NMR Spectroscopy

The action of a series of lanthanide chelate complexes LnL₃, where Lu=La, Pr, Nd, Sm, Eu, Dy, Ho, Er and Yb; L= dbm (dibenzoylmethanato), dpm (dipivaloylmethanato), and acac acetylactonato), on nmr spectra of 2-butanol has been studied. The origin of shifting abilities and shifting sign of various lanthanide ions are explained by means of Bleaney's theory.     

Development of soft-based double-stranded peptide chelators which selectively separate europium and lanthanum ions based on the hardness concept

New double-stranded peptide chelators (1) conjugated Cat (2,3-dihydroxybenzoic acid) were synthesized and formed a molecular complex 1-Eu(3+) (or 1-Lu(3+)) with Eu(3+) and Lu(3+) but not La(3+). The double-stranded peptide chelator may prove to be useful tools for studying the selective separation of lanthanide ions.     

Structures and fluorescence of two new hetero-dinuclear lanthanide(III) complexes derived from a Schiff-base ligand

Two isostructural dinuclear lanthanide(III)/Schiff-base complexes [{Ce_1.5Eu_0.5(clapi)}₂]·2CH₃CN (1) and [{La_1.5Eu_0.5(clapi)}₂]·2CH₃CN (2) {H₃clapi = 2-(5-chloride-2-hydroxyphenyl)-1,3-bis[4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared by template procedure and characterized by elemental analyses, ICP, IR, and single-crystal X-ray diffraction analyses. Lanthanide ions Ce(III) and Eu(III) in 1, and La(III) and Eu(III) in 2 are disordered with occupancies 0.75 for Ce and 0.25 for Eu in 1; 0.75 for La and 0.25 for Eu in 2. In the compounds, each lanthanide is coordinated to four N and four O atoms from two clapi^3? ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate μ₂-bridging ligands connect the two Ce(Eu) atoms in 1, and La(Eu) in 2. The solution of the two complexes in CH₂Cl₂ exhibits red fluorescence from Eu³⁺ ions at 77 K, very weak at room temperature.     

Preparation and surface effect analysis of trivalent europium-doped nanocrystalline La2O2S

La2O2S:Eu3+ nanocrystals (NCs) with a mean size of 18 nm are prepared by gel thermolysis. The morphology of the particles is hexagonal. The surface Eu3+ ions are first detected by time-resolved spectra in the 5D0 --> 7F1 region. Because the symmetry of the sites occupied by surface Eu3+ ions is lower, the 5D0 --> 7F1(E) line, which is doubly degenerate in the bulk crystal, is split, and the fluorescence lifetime becomes shorter. The results of the laser-selective excitation indicate that the degradation of the site symmetry of Eu3+ seems to be abrupt, which means the as-synthesized La2O2S:Eu3+ NCs might be of the La2O2S/La2O(2-x)S(1+x)core-shell structure and the shell are not in a disordered state but a rather pure one.     

Solvation of uranyl(II), europium(III) and europium(II) cations in "basic" room-temperature ionic liquids: a theoretical study

We report a molecular dynamics study of the solvation of UO2(2+), Eu3+ and Eu2+ ions in two "basic" (Lewis acidity) room-temperature ionic liquids (IL) composed of the 1-ethyl-3-methylimidazolium cation (EMI+) and a mixture of AlCl4- and Cl- anions, in which the Cl-/AlCl4- ratio is about 1 and 3, respectively. The study reveals the importance of the [UO2Cl4]2- species, which spontaneously form during most simulations, and that the first solvation shell of europium is filled with Cl- and AlCl4- ions embedded in a cationic EMI+ shell. The stability of the [UO2Cl4]2- and [Eu(III)Cl6]3- complexes is supported by quantum mechanical calculations, according to which the uranyl and europium cations intrinsically prefer Cl- to the AlCl4- ion. In the gas phase, however, [Eu(III)Cl6]3- and [Eu(II)Cl6]4- complexes are predicted to be metastable and to lose two to three Cl- ions. This contrasts with the results of simulations of complexes in ILs, in which the "solvation" of the europium complexes increases with the number of coordinated chlorides, leading to an equilibrium between different chloro species. The behavior of the hydrated [Eu(OH2)8]3+ complex is considered in the basic liquids; the complex exchanges H2O molecules with Cl- ions to form mixed [EuCl3(OH2)4] and [EuCl4(OH2)3]- complexes. The results of the simulations allow us to better understand the microscopic nature and solvation of lanthanide and actinide complexes in "basic" ionic liquids.     

稀土及其配合物对蛇毒磷脂酶A_2活性的影响

分别研究了三价稀土离子 (La3 + ,Eu3 + ,Dy3 + ,Yb3 + )、二乙三胺五乙酸及其衍生物二乙三胺五乙酸 -双二甲酰胺 ,二乙三胺五乙酸 -双 (异烟肼 )与稀土离子的配合物以及Tb -谷氨酰胺配合物对蛇毒磷脂酶A2 活性的影响 .浓度低于 <3μmol/L的稀土离子可以激活磷脂酶A2 ,浓度大于 5 μmol/L后稀土离子对酶活性表现出抑制作用 ;外源Ca2 + 离子的加入可以缓解稀土离子对酶活性的抑制作用 ,表明稀土离子和钙离子是竞争性地结合在酶的活性部位 ;稀土离子和二乙三胺五乙酸及其衍生物的配合物对酶活性没有明显影响 ;Tb -谷氨酰胺在浓度大于 10 μmol/L后开始抑制酶的活性