Spectrofluorometric determination of trace amounts of terbium with 4-chlorosalicylic acid, EDTA, and cetyltrimethylammonium bromide.

The quadruple complex formed by terbium with 4-chlorosalicylic acid (CSA), EDTA and cetyltrimethylammonium bromide (CTMAB) has been used for the sensitive spectrofluorometric determination of terbium in mixed rare earths. The effect of the experimental conditions on the fluorescence intensity was defined. Under the optimum conditions selected, the fluorescence intensity was linear with the terbium concentration in the range of 3.0 x 10(-8)-1.0 x 10(-5) mol/L with a detection limit of 8.0 x 10(-9) mol/L (S/N = 3). It has been satisfactory for the determination of terbium in mixed rare earths with good recovery.     

Spectrofluorimetric determination of terbium as its ternary complex with edta and tiron Compositional studies,optimization of fluorescence output and conversion to a flow system

The spectrofluorimetric determination of terbium(III) as its ternary complex with EDTA and Tiron was studied further with regard to composition of the complex and the procedure was optimized by a simplex method. The results suggest a 1:1 molar ratio of terbium to Tiron for the ternary complex. The optimization study indicated that the three chosen variables (pH, and EDTA and Tiron concentration) are not interactive. The method was converted for use in a segmented-flow system with basic Technicon units and a spectrophotofluorimeter as detector. This procedure is satisfactory for the determination of terbium(III) in the range 0.03–0.24 μg ml^?1 at a sampling rate of 30 h^?1. Results were satisfactory for the determination of terbium in lanthanide oxides, mixed oxides, the mineral bastnasite and a green phosphor (Gd_0.96 Ce_0.02 Tb_0.02 F₃).     

聚N-异丙基丙烯酰胺-丙烯酸共聚微凝胶与Tb(Ⅲ)相互作用的研究

聚N-异丙基丙烯酰胺(PNIPAM)微凝胶是一类具有独特的温度响应性,即具有最低临界溶解温度(LCST)的高分子化合物,由于具有了LCST性能,当PNIPAM微凝胶受热时,在较窄的温度范围内,溶胀于微凝胶内的溶剂被挤出,从而导致微凝胶的粒子尺寸、粒子形态、亲水性、胶体稳定性以及微凝胶分散液的粘度、电泳流动性发生较大改变的现象。     

Synthesis and novel fluorescence phenomenon of terbium complex with a new Schiff base ligand derived from condensation of triaminotriethylamine and 3-indolemethanal

A new Schiff base ligand with tripodal structure, N,N',N'-tri-(3-indolemethanal)-triaminotriethylamine (L), and its complex with terbium was synthesized. The complex was characterized by element analysis, IR spectra, mass spectra, thermal analysis and molar conductivity. The terbium ion was found to coordinate to the Schiff base nitrogen atoms and the bridgehead nitrogen atom. The fluorescence properties of the complex in aqueous solutions were studied. Under the excitation of UV light, the complex exhibits characteristic fluorescence of terbium ion. H(+) concentration could strongly enhance the luminescence of terbium complex with L in aqueous solutions. This phenomenon will make the new complex favorable to be used in the fluorescence switches and sensors. The mechanism of the fluorescence enhancement by protonation of the indole nitrogen atoms is due to the suppressed photoinduced electron transfer (PIET) fluorescence quenching when adding acid.     

A long-lived luminescence and EPR bimodal lanthanide-based probe for free radicals

We developed a novel spin-labeled terbium complex Tb(3+)/cs124-DTPA-TEMPO (1) by covalently labeling a nitroxide radical on the terbium complex for monitoring free radicals of various areas. This lanthanide complex probe shows a high EPR signal which resulted from the nitroxide radical moiety, and is weakly luminescent which resulted from the intramolecular quenching effect of the nitroxide radical on sensitised terbium luminescence. The intensity of both the EPR and luminescence can be modulated by eliminating the paramagnetism of the nitroxide radical through recognition of a carbon-centered radical analyte and thus gives a quantification of the analyte. We have preliminarily applied this probe in the luminescent detection of model carbon-centered radicals and hydroxyl radicals (·OH). This probe is water-soluble and contains lanthanide-luminescence properties, favorable for the time-resolved luminescence technique. The investigation of the intramolecular quenching process has showed that the labeled nitroxide radical quenches multiple excited states of the terbium complex, resulting in highly efficient quenching of terbium luminescence. This probe is the first example of intramolecular modulation of lanthanide luminescence by a nitroxide radical.     

Investigation of the hydrophobization efficiency of terbium-exchanged BEA zeolites by means of FT-IR, TGA, physical adsorption, and time-resolved photoluminescence

Terbium-exchanged BEA zeolites were hydrophobized with phenyl-, vinyl-, and hexadecyltrimethoxysilanes by means of postsynthesis grafting. These materials were investigated using XRD, FT-IR, TGA, physical adsorption, and photoluminescence. Different methods for the analysis of the non-exponential decay of terbium photoluminescence in BEA zeolites were used ranging from discrete exponential to more complex approaches based on maximum entropy and global analysis. Two groups of decay times varying between 480 and 580 micros and 1-1.3 ms were assigned to the lifetimes of terbium exposed to water (unprotected) and protected by the organic groups, respectively. Our results showed that the preservation of terbium PL properties against detrimental effects of moisture adsorption could be ordered in the following sequence: hexadecyl > phenyl approximately vinyl. The photoluminescence results were in good agreement with the FT-IR, TGA, and physical adsorption data.     

螯合剂对稀土-转铁蛋白配合物的影响(Ⅱ)——稀土-转铁蛋白配合物的阴离子结合性质

在0.1mol/LHepes,pH 7.4 的条件下,使用紫外差谱和铽(Ⅱ)荧光光谱观察了一些螯合剂对稀土-转铁蛋白配合物REC-apoTf中RE的脱除.荧光滴定表明,螯合剂对TbC-apoTf中铽(Ⅱ)的脱除按缔合机理进行.当螯合剂为非伴阴离子时,脱除过程有TbC-apoTf-L三元配合物中间体生成;当螯合剂为伴阴离子时,脱除过程有L-TbC-apoTf三元配合物中间体生成;L-TbC-apoTf比TbC-apoTf-L更有利于脱除反应的进行;HEDTA,EDTA和NTA可定量地将TbC-apoTf转化为Tb-L或Tb-L2小分子配合物.     

Crystal structure,and thermal and magnetic properties of 2,4-dinitrobenzoatoterbium(III) complex

The Tb(III) complex containing 2,4-dinitrobenzoate (2,4-DNB), Tb(2,4-DNB)₃(H₂O)₂]?·?C₂H₅OH has been synthesized and its crystal structure analyzed by X-ray diffraction methods. The complex crystallizes in the triclinic space group P 1, as a linear polymeric chain in which terbium ions are bridged by carboxylate groups. The eight-coordinate Tb ion with six carboxylate groups and two water molecules forms a slightly distorted square antiprism. Thermal and magnetic properties of the terbium complex were also studied.     

Dendrimers as ligands. Formation of a 2:1 luminescent complex between a dendrimer with a 1,4,8,11-tetraazacyclotetradecane (cyclam) core and Zn2+

We have investigated the formation of metal complexes between Zn2+ and two derivatives, 1 and 2, of the well-known 1,4,8,11-tetraazacyclotetradecane (cyclam) ligand. Compound 1 is 1,4,8,11-tetrakis(naphthylmethyl) cyclam, and compound 2 is a dendrimer consisting of a cyclam core with appended 12 dimethoxybenzene and 16 naphthyl units. Compound 1 exhibits an emission band with a maximum around 480 nm, assigned to the formation of exciplexes between amine and excited naphthyl units. Dendrimer 2 exhibits three types of weak emission bands, assigned to naphthyl localized excited states (lambdamax = 337 nm), naphthyl excimers (lambdamax ca. 390 nm), and naphthyl-amine exciplexes (lambdamax = 480 nm). In CH3CN-CH2Cl2 1:1 v/v, titration of ligand 1 with Zn2+ causes the disappearance of the exciplex emission and the appearance of a strong naphthyl localized fluorescence; the titration plot is linear and reaches a plateau for a 1:1 stoichiometry, showing that a highly stable [Zn(1)]2+ complex is formed. In the case of 2, titration with Zn2+ causes the disappearance of the exciplex band, with a concomitant increase in the excimer and naphthyl localized emissions; the titration plot is again linear, but in this case it reaches a plateau for a 2:1 stoichiometric ratio, showing the unexpected formation of a [Zn(2)2]2+ complex. Such an unexpected stoichiometry for the complex of the dendritic ligand has been fully confirmed by 1H NMR titrations. The results obtained show that the dendrimer branches not only do not hinder, but in fact favor coordination of cyclam to Zn2+.     

Synthesis and properties of coumarin derivatives and their terbium complexes

A series of coumarin derivatives obtained from salicylaldehyde and phenol were synthesized. Their corresponding terbium complexes were prepared and characterized by elemental analysis, EDTA titrations, molar conductivity, UV–vis spectra, IR spectra, and thermal analysis. The luminescent properties and electrochemical properties of the terbium complexes were also investigated. The results showed that all the terbium complexes exhibited characteristic emissions of terbium ions. The introduction of electron-donating groups can improve the luminescent properties, decrease the HOMO and LUMO energy levels of the terbium complex, while electron-withdrawing groups can weaken the luminescent properties, and increase the HOMO and LUMO energy levels of terbium complex.     

Enhancement of fluorescence of terbium/trimesic acid/cyclodextrin system by zirconate and its application to the determination of terbium

A new approach of fluorescence enhancement for the determination of terbium based on the formation of a new fluorescence system of Tb-TMA-beta-CD (benzene-1,3,5-tricarboxylic acid (TMA), beta-cyclodextrin (beta-CD)) in an aqueous medium of pH 5.0 provided by a HAc-NaAc buffer in the presence of an oxy-acid of transition metal, zirconate acid, is reported. The maximum excitation and emission wavelengths are 301 nm and 545 nm for the terbium complex, respectively. Under the optimal conditions, the method allows the determination of terbium over the range of 0.508-521 ng ml(-1) with a S.D. of 0.392, and the recovery is in the range of 99.0-100.1%. The emulsion formed by Tb-TMA-beta-CD with zirconate acid makes the determinate system more stable than the system of Tb-TMA-beta-CD. The proposed method has been employed for the determination of some international standard reference or samples with a good precision (RSD < 1.7%, n = 5).     

Synthesis,quantum chemical calculations,and luminescent properties of scandium,europium, gadolinium,and terbium 1-(2-pyridyl)naphtholate complexes

By reactions of 1-(2-pyridyl)naphth-2-ol (pynH) with silylamides Ln[N(SiMe₃)₂]₃ (Ln = Sc, Eu, Gd, or Tb), the Ln(pyn)₃ complexes of the metals have been synthesized. Only the scandium complex in a THF solution has displayed photoluminescence (band with a maximum at 455 nm and a halfwidth of 65 nm). Electroluminescent properties have been revealed for the scandium and terbium complexes. In an ITO/TPD/Sc(pyn)₃/Bath/Yb three-layer light emitting diode, the scandium complex exhibits yellow-green luminescence with a brightness of 4750 cd/m² at a voltage of 21 V. The terbium complex Tb(pyn)₃ in the same device has displayed a single, broad luminescence band with λ_max = 570 nm due to excimer emission. By density functional theory quantum chemical calculations, different structures of the complexes have been revealed, mononuclear for Sc(pyn)₃ and binuclear for Ln₂(pyn)₆. This difference in structure seems to be responsible for differences in electroluminescent activity between the synthesized complexes.     

In-Situ Synthesis of Terbium Complex with Salicylic Acid in Silica Matrix by a Two-Step Sol-Gel Process

Sincesomelanthanideionspossessgoodlundnescentcharacteristicsbasedontheelectronictransitionsbetweenthe4fenergylevels,aseriesofrareearthcompoundshavebeenstudiedforpracticalapplicationsasphosphors.However,sincethef-ftransitionsoftheseionsareparityforbidden,theintensityofabsorptionbandsareusuallyrelativelyweak.Itiswellknownthatorganicligandsusuallyhavehighultravioletmolarabsorptivity.Ifthecomplexesthatcontainthiskindofligandsaresynthesized,theywillgivestrongluminescence.Infact,sofarmanyphotoactive…     

Ultrasensitive detection of phenolic compounds based on a spin-labeled luminescent lanthanide complex

Herein we propose a novel method for ultrasensitive detection of phenolic compounds. This method was developed based on a spin-labeled terbium complex Tb(3+)/cs124-DTPA-TEMPO (1). This spin-labeled terbium complex is a weakly luminescent compound and shows strong off-on luminescent response to phenolic compounds in the presence of horseradish peroxidase (HRP), glutathione (GSH) and hydrogen peroxide. The analyte recognition and signaling mechanism are discussed and the factors affecting the off-on luminescence have been explored. Detection limits of 1.1 nM for phenol, 1.1 nM for resorcine, 0.6 nM for m-cresol, 3 nM for p-cresol, and 0.5 nM for 2,4-dichlorophenol were obtained, respectively. The practicability of the proposed method has been tested in detection of the concentration of spiked nearshore seawaters, and recoveries of 77.4-80.4% with relative standard deviations (RSDs) of 1.0-2.2% were obtained.     

A novel terbium complex using oxadiazole derivative as a neutral ligand： Synthesis and properties

A novel terbium complex using 1,3,4-oxadiazole derivative as a neutral ligand was synthesized and characterized. Its thermal stability and photoluminescent properties were studied. The strong emission peaked at 546 nm with a full width at half maximum of 5 nm was observed in the pure terbium complex film under excitation of 328 nm light, which is attributed to the characteristic emission of terbium ion. The good thermal stability and intense sharp emission of this terbium complex display its potential application in electroluminescence devices.     

Structure, stability, dynamics, high-field relaxivity and ternary-complex formation of a new tris(aquo) gadolinium complex

The tripodal hexadentate picolinate ligand dpaa3- (H3dpaa=N,N'-bis[(6-carboxypyridin-2-yl)methyl]glycine) has been synthesised. It can form 1:1 and 1:2 lanthanide/ligand complexes. The crystal structure of the bis(aquo) lutetium complex [Lu(dpaa)(H2O)2] has been determined by X-ray diffraction studies. The number of water molecules was determined by luminescence lifetime studies of the terbium and europium complexes. The tris(aquo) terbium complex shows a fairly high luminescence quantum yield (22 %). The [Gd(dpaa)(H2O)3] complex displays a high water solubility and an increased stability (pGd=12.3) with respect to the analogous bis(aquo) complex [Gd(tpaa)(H2O)2] (pGd=11.2). Potentiometric and relaxometric studies show the formation of a soluble GdIII hydroxo complex at high pH values. A unique aquohydroxo gadolinium complex has been isolated and its crystal structure determined. This complex crystallises as a 1D polymeric chain consisting of square-shaped tetrameric units. In heavy water, the [Gd(dpaa)-(D2O)3] complex shows a quite high HOD proton relaxivity at high field (11.93 s(-1) mM(-1) at 200 MHz and 298 K) because of the three inner-sphere water molecules. The formation of ternary complexes with physiological anions has been monitored by relaxometric studies, which indicate that even under conditions favourable to the formation of adducts with oxyanions, the mean relaxivity remains higher than those of most of the currently used commercial contrast agents except for the citrate. However, the measured relaxivity (r1=7.9 s(-1) mM(-1)) in a solution containing equimolar concentrations of [Gd(dpaa)(D2O)3] and citrate is still high. The interaction with albumin has been investigated by relaxometric and luminescence studies. Finally, a new versatile method to unravel the geometric and dynamic molecular factors that explain the high-field relaxivities has been developed. This approach uses a small, uncharged non-coordinating probe solute, the outer-sphere relaxivity of which mimics that of the water proton. Only a routine NMR spectrometer and simple mathematical analysis are required.     

铽配合物Tb(PMIP)3(PhCA)的合成及阴离子识别研究

本文设计合成了稀土铽配合物Tb(PMW)3(PhCA)作为阴离子试剂,利用荧光光谱考察了其与F-、Cl-、Br-、I-、ClO4-、NO3-、AcO-和H2PO-4等阴离子的作用.研究结果表明:不同阴离子的加入能够调控,Tb(PMIP)3(PhCA)的发光行为,当一定量的氟离子(醋酸根离子、磷酸二氢根离子)加入到Tb(PMIP)3(PhCA)的乙腈溶液中后,荧光发射增强;过量的氟离子(醋酸根离子、磷酸二氢根离子)加入后则使其荧光淬灭.而在乙腈和水混合溶液中,Tb(PMIP)3(PhCA)则能选择性识别氟离子和磷酸二氢根离子.     

Flow Injection Spectrofluorimetric Determination of Terbium (III) Based on Solubilizing its Ternary Complex in Micellar Solution

Abstract

A flow injection spectrofluorimetric method has been developed for the determination of terbium (III) based on solubilizing its ternary complex with pi valoyitrifluoroacetone (PTA) and trioctylphosphine oxide(TOPO) in micellar solution of nona (oxyethylene) dodecyl ether (BL-9EX). Accuracy and reproducibility are good up to 16 ng/ml of terbium (III) and 80 samples per hour can be analyzed. The relative standard deviation was less than 1.0 %. No interferences from 20-fold excesses of 11 rare earth ions were observed.     

Terbium(III) as fluorescence probe in the study of the interaction of rare earth and transition metal ions with concanavalin A

The binding site for calcium (II) on concanavalin A (con-A) can be occupied by rare earth ions. When terbium (III) ion binds to con-A, its fluorescence intensity is tremendously enhanced because of an energy transfer from one or more tryptophan residues in close proximity to the bound terbium (III). The dissociation constant of the con-A-Tb (III) complex is 8.90 × 10^?6M, obtained from terbium (III) fluorescence titration with con-A. The dissociation constant of the complexes of con-A with other rare earth and transition metal ions was obtained through their competition with terbium (III) in the reaction with con-A, i. e. the quenching of con-A enhanced fluorescence. The results indicate that the binding of rare earth ions with con-A is dependent not only on their ionic radius but also on the hard-soft acid-base strength of the metal ions.     

稀土铕、铽配合物在温度发光传感领域的研究进展

稀土发光配合物材料基于其独特的4f-4f电子跃迁表现出优异的发光性能,特别是铕和铽配合物材料,发光波长在可见光区范围内,发射谱带狭窄且尖锐(半峰宽通常小于10 nm),非常适合应用于显示设备和传感装置.同时,具备温度依赖发光性能的铕和铽配合物能够实现高灵敏度、高效的温度传感过程,使其有望用于流体动力学、航空航天、环境工...