Tb^(3+)-nucleic acid probe-based label-free and rapid detection of mercury pollution in food

Mercury is a threatening pollutant in food,herein,we developed a Tb^(3+)-nucleic acid probe-based label-free assay for mix-and-read,rapid detection of mercury pollution.The assay utilized the feature of light-up fluorescence of terbium ions(Tb^(3+))via binding with single-strand DNA.Mercury ion,Hg^(2+)induced thymine(T)-rich DNA strand to form a double-strand structure(T-Hg^(2+)-T),thus leading to fluorescence reduction.Based on the principle,Hg^(2+)can be quantified based on the fluorescence of Tb^(3+),the limit of detection was 0.0689μmol/L and the linear range was 0.1-6.0μmol/L.Due to the specificity of T-Hg^(2+)-T artificial base pair,the assay could distinguish Hg^(2+)from other metal ions.The recovery rate was ranged in 98.71%-101.34%for detecting mercury pollution in three food samples.The assay is low-cost,separation-free and mix-to-read,thus was a competitive tool for detection of mercury pollution to ensure food safety.

Spectrofluorimetric determination of terbium(Ⅲ) by fluorescence enhancement system of Tb-TPA-Triton X-100 by La^(3+)

The phenomenon of fluorescence enhancement for the system of terbium(b!) with terephthalic acid (benzene-1,4-dicarboxylic acid (TPA)) in the presence of an excess of La3+ in Triton X-100 aqueous solution has been studied. The fluorescence intensity of Tbb!-TPA system can be greatly increased by La3+. The intermolecular transfer of energy was responsible for the mechanism of the fluorescence enhancement. Triton X-100 plays an important role for the stabilization of the system. The system, having the maximum excitation and emission wavelengths at 256 nm and 546 nm, respectively, shows a constant fluorescence intensity over the pH range between 4-6. The fluorescence intensity is a linear function of Tb3+concentration in the range of 1.00 ?

Preparation of Terbium Sesquisulfide and Holmium Sesquisulfide by Sulfurization of Their Oxide Powders Using CS_2 Gas

The formation behaviors of terbium sesquisulfide(Tb_2S_3)and holmium sesquisulfide(Ho_2S_3)synthesized via the sulfurization of their oxide powders using CS_2 gas in the range of temperature 673 to 1323 K were investigated. In the sulfurization of Tb_4O_7 powder, Tb_2O_3 and Tb_2O_2S were formed in the initial stage of reaction, and α-Tb_2S_3 was finally formed at higher temperature. For long sulfurization time of 8 h, single-phase α-Tb_2S_3 could be synthesized at 1323 K. In the sulfurization of Ho_2O_3 powder using CS_2 gas, only Ho_2O_2S was formed as an intermediate product. At a sulfurization temperature above 873 K, Ho_2O_2S was formed in the initial stage of reaction, and single-phase δ-Ho_2S_3 was formed at 1323 K for 8 h instead of Ho_2O_2S. Furthermore, the influence of the addition of carbon black to the sulfurization of Ho_2O_3 powder using CS_2 gas was investigated, and the result implied that the reactions were accelerated slightly by the addition of carbon black.

Synthesis,Characterization and Fluorescence Properties of Europium,Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu(phen)L3·1/2H2O, Eu0.5RE0.5(phen)L3·1/2H2O; Tb(phen)L3·H2O and Tb0.5RE0.5(Phen)L3·1/2H2O. (RE=Y3+, La3+ and Gd3+; L=biphenyl 4-carboxylic acid; phen=o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE(Ⅲ) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu3+ is raised by inert fluorescent rare earth ions (Y3+, Gd3+ and La3+), but in Tb3+ hetero-nuclear rare earth complexes the intensity of Tb3+ ions are quenched by the inert fluorescent rare earth ions.

Fluorescence enhancement and cofluorescence in complexes of terbium(III) with trimellitic acid

The fluorescence of terbium （Ⅲ） was enhanced by about three orders of magnitude in the presence of trimellitic acid （benzene-1, 2, 4-tricarboxylic acid （TLA）） in aqueous solution at pH 6. The fluorescence intensity could be greatly increased when the system of Tb^3＋-TLA was treated with La^3＋ （or Gd^3＋） and TritonX- 100. The addition of La^3＋ （or Gd^3＋） enhanees the fluorescence of the system by about two orders of magnitude due to cofluorescenee, and the TritonX-100 micellar medium plays an important role for stabilization of the system. Both the intermolecular energy transfer mode and intramolecular energy transfer mode are responsible for the mechanism of fluorescence enhancement. In the optimum condi- tions, the fluorescence intensity is a linear function of Tb3~ concentration in the range of 7.8 × 10^-9-3.6 × 10^4 mol/L for the system Tb^3＋-La^3＋-TLA and 1.0 × 10^-8-4.7 × 10^-5 mol/L for the system Tb^3＋-Gd^3＋-TLA, and the limits of detection are 4.6 × 10^-10 mol/L and 6.0 × 10^-10 mol/L, respectively.

Crystal Structure and Properties of a Terbium Benzoate Complex with 1,10-Phenanthroline

A terbium benzoate complex with 1,10-phenanthroline [Tb(ba)3(phen)]2, where ba = benzoate and phen = 1,10-phenanthroline, has been prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group P1 with a = 10.7881(5), b = 11.9262(6), c = 12.4249(6) ?, a = 105.1260(10), β = 93.6010(10), ? = 113.3350(10)o, (C33H23N2O6Tb)2, Mr = 1404.90, V = 1391.87(12) ?3, Z = 1, Dc = 1.676 g/cm3, μ(MoKα) = 2.590 mm-1, F(000) = 696, the final R = 0.0277 and wR = 0.0670 for 6085 observed reflections with I > 2σ(I). The crystal consists of binuclear molecules of the title compound. Each Tb3+ ion is nine-coordinated to one 1,10-phenan- throline molecule, one bidentate carboxylate group and four bridging carboxylate groups. The carboxylate groups are bonded to the terbium ion in three modes: the chelating bidentate, bridging bidentate and bridging-chelating tridentates. Excitation and luminescence data observed at room temperature show that the title complex emits very intensive green fluorescence under ultraviolet light. The results of thermal analysis indicate that the complex [Tb(ba)3phen]2 is very thermal stable.

Crystal structure and properties of terbium o-methylbenzoate complex with 1,10-phenanthroline [Tb(o-CH_3C_6H_4COO)_3(C_(12)H_8N_2)]_2

A terbium o-methylbenzoate complex with 1,10-phenanthroline, Tb(o-MBA)_3phen(where o-MBA = o-methylbenzoate and phen = 1,10-phenanthroline) was prepared from ethanol solutionand its crystal structure was determined by X-ray diffraction. The crystal of the complexTb(o-MBA)_3phen belongs to triclinic crystal system and P1 (#2) space group. The crystal data are asfollows: a = 1.4371(4) nm, b = 1.7387(2) nm, c = 1.3109(2) nm, α = 96.37(1)°, β = 107.21(2)°,γ= 82.78(2)°, Ⅴ= 3.094(1) nm^3, Z= 2, M_r = 1489.12, D_c= 1.598 g·cm^(-3), μ = 2.330 mm^(-1)and F(000) = 1488.00. The final R and R_w are 0.038 and 0.047 for 8668 [Ⅰ > 2σ(Ⅰ)] uniquereflections, respectively. In the complex each Tb^(3+) ion is eight-coordinated by one1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups.The carboxylate groups are bonded to the terbium ion in two modes: the chelating bidentate and thebridging bidentate. Excitation and luminescence data observed at room temperature show that thetitle complex emits strong green fluorescence under ultraviolet light. The results of thermalanalysis indicate that the complex Tb(o-MBA)_3phen is quite stable to heat.

Binding Constants for Terbium(Ⅲ) with Chicken Apoovotransferrin

The binding of Tb 3+ to chicken apoovotransferrin was studied by monitoring the fluorescent intensity of Tb 3+ at 549 nm. The conditional equilibrium constants for the complexation of Tb 3+ by chicken apoovotransferrin in 0 1 mol/L hepes, at pH 7 4 and room temperature were measured. The successive macroscopic binding constants are lg K 1=9 08±0 12 and lg K 2=7 36±0 22. The molar fluorescence enhancement of Tb 3+ apoovotransferrin complex is (2 06±0 14)×10 4 mol -1 ·L. The fluorescence quenching experiment and the titration of N terminal monoferric ovotransferrin showed that Tb 3+ has a preference for being bound to the N terminal binding site of apoovotransferrin.

Co－fluorescence Enhancement System Based on Lanthanum（Ⅲ） for Determination of Terbium（Ⅲ）

The phenomenon of fluorescence enhancement for the system of terbium( Ⅲ ) with trimesic acid [ ben-zene-1, 3, 5-tricarboxylic acid (TMA)] in the presence of an excase of La￣(3+) in gelatin aqusous solution wasstudied. The fluorescence intensity of Tb￣Ⅲ -TMA system can be greatly increased by La￣(3+) , which causedthe largest enhancement of the fluorescence intensity over two orders of magnitude. The intermolecular transfer of energy was responsible for the mechanism of the fluorascence enhancement. Gelatin plays animportant role for the stabilization of the system. The system, having the maximum excitation and emis-sion wavelengths at 260 nm and 549 nm, respectively, shows a constant fluorescence interisity over the pHrange 4～6. The fluorescence intensity is a linear function of Tb￣(3+) concentration in the range of 8. 0 ×10 ￣(-9)～ 2. 6 × 10￣(-7) mol· L￣(-1) and the limit of detection is 2.0 × 10￣(-9) mol·L￣(-1) . The optimized procedurewas used for the determination of trace amount of terbium in rare earth oxides and international standardreference rocks with satisfactory results.

Synthesis and Characteristic of Poly(N-vinylacetamide) Containing Terbium Ion

Poly (N-vinylacetatnide) ( PNVA) was synthesized by free radical polymerization in ethanol solution, in which alpha, alpha'-azobisisobutyronitrile was used as an initiator. Tb(III)-PNVA polymer was prepared and characterized by ultraviolet-visual (UV), fourier transform infrared (FIF-IR), X-ray photoelectron spectroscopy (XPS) and fluorescence spectroscopy. The experimental results of UV, FT-IR and XPS show that the Tb (III)-PNVA electrovalent complex is formed by electrostatic interaction between terbium (III) cation and complexible atoms of acylamino group in the pendant chain of the polymer. The fluorescence spectrum of the complex exhibits intensive characteristic emission of terbium at 490, 545 and 584 run, which are assigned to D-5(4)->F-7(6), D-5(6)->F-5(6) and D-5(4)->F-7(3) transition, indicating that there exists an efficient intermolecular energy transfer from the polymer ligand to the central rare earth ion. The emission intensity of the complex is increased with the increasing concentration of Tb (III) ion until the weight ratio of Tb (III) on to PNVA is 1.5% (mass fraction), and decreased with the further increasing concentration of Tb (III) ion, which is a typical concentration quenching behavior.

Upconversion Photoluminescence and Energy Transfer Mechanism of a Novel Terbium-mercury Compound

A novel terbium-mercury complex [Tb(IA)3(H3 O)2]2 n(2 n HgCl4)(n Hg2 Cl5)·n H3 O· 3 n H2 O(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the C2/c space group of monoclinic system with a = 24.2347(5), b = 20.8342(6), c = 15.3206(3) ?, β = 128.257(2)°, V = 6074.3(2) ?3, C36H41Cl13Hg4N6O20Tb2, Mr = 2458.80, Z = 4, Dc = 2.689 g/cm3, μ(Mo Kα) = 13.014 mm–1 and F(000) = 4520. The crystal structure of 1 is characterized by a one-dimensional(1-D) chain-like structure. Solid-state UV/Vis diffuse reflectance spectrum reveals the existence of a wide optical band gap of 3.36 eV. Solid-state photoluminescence experiment uncovers that it shows reddish brown upconversion emission. The emission bands are originated from the characteristic emission of the 4 f electrons intrashell transition of the 5D4 → 7 FJ(J = 6, 5, 4) of the Tb3+ ions. Energy transfer mechanism is explained by the energy level diagram of the Tb3+ ion and the isonicotinic acid ligand. It shows a remarkable CIE chromaticity coordinates(0.4158, 0.4005).

Physical Properties of Liquid Terbium Measured by Levitation Techniques

To understand the nature and behavior of rare earth metals in their liquid phases, accurate values of their physical properties are essential. However, to measure their physical properties, the samples should be maintained in liquid phases for prolonged time, and this raises a formidable challenge. This is mainly explained by their high melting temperatures （e.g., 1629 K for Tb）, high vapor pressure, and the risk of melt contamination with a crucible or support. An electrostatic levitation furnace alleviated these difficulties and allowed the determination of density, surface tension, and viscosity of several metals above their melting temperature. Here, first, the levitation furnace facility and the noncontact diagnostic procedures were briefly discussed, followed by the explanation of their thermophysical property measurements over wide temperature ranges. The density was obtained using an ultraviolet-based imaging technique that allowed excellent illumination, even at elevated temperatures. Over the 1615 to 1880 K temperature span, the density measurements could be expressed as p（T） =7.84 × 10^3 -0.47 （T - Tm） （kg · m^-3） with Tm = 1629 K, yielding a volume expansion coefficient a（T） = 6.0 × 10^-5 （K^-1）. In addition, the surface tension and the viscosity could be determined by inducing a drop oscillation to a molten sample. Using this technique, the surface tension data could be expressed as σ（T） = 8.93 × 10^2 - 0.10 （T - Tm）（mN· m^-1） and those for viscosity as η（T） =0.583 exp [4.1 × 10^4/（RT）] （MPa·s） over the 1690 to 1980 K temperature range

Synthesis, Characterization and Fluorescence of Terbium(Ⅲ) Complexes with Phenylglyoxylic Acid and 2,2-Dipyridine, 1,10-Phenanthroline, Triphenyl Phosphine Oxide

Three new complexes TbL3dipy （H2O）2, TbL3phen （H2O） 2 and TbL2 （TPPO） 2NO3 were synthesized （L = phenylglyoxylate ion, dipy = 2, 2-dipyridine, phen = 1,10-phenanthmline, TPPO = Triphenyl phosphine oxide）. Elemental analysis, conductivity, IR spectra, and ^1HNMR spectra studies were performed. IR spectra indicate that the carboxylate ion of phenylglyoxylate is coordinated to the Tb（Ⅲ） ion as an unidentate ligand. In ^1HNMR, the signals of different hydrogens in phenylglyoxylate ion shift upfield. The excitation and emission spectra of the three solid complexes were recorded at morn temperature, in which the optimum excitation wavelengths are, 361.0, 359.0 and 367.0 nm for these three complexes, respectively. Four emission bands due to the ^5D4-^7Fj（j = 6, 5, 4, 3） transitions were observed for TbL3dipy（H2O）2（489.0, 545.0, 584.0, 620.0 nm） and TbL3phen（H2O）2（490.0, 544.0, 583.0, 620.0 nm）. Under the same conditions, only one emission band due to the ^5D4-^7F5 transition was observed for the complex TbL2（TPPO）2NO3. The emission intensity of TbL3dipy（H2O）2 is the strongest among the three complexes.

Dual Functional Methoxyterephthalic Acid Terbium Complex with Luminescence and Magnetim

A dual functional coordination polymer, namely, {[Tb（mat）（1.5）H2O]·2.5H2O}n（1, H2mta = 2-methoxyterephthalic acid）, was synthesized under solvothermal condition and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, X-ray powder diffraction analysis（PXRD）, and thermogravimetric analysis（TGA）. Complex 1 exhibits a 3D framework based on infinite rod-shaped secondary building units（SBUs）. Furthermore, the solid-state luminescent property and magnetic properties of the complex were investigated at room temperature; the results show that the complex exhibits excellent luminescent properties in green luminescence and weak antiferromagentic behavior.

Sol Gel Assembly and Luminescence of SiO_2/PEMA Hybrid Material Incorporated with Terbium Complex

Ethyl methacrylate (EMA) doped with luminescent ternary terbium complex (Tb(acac) 3·dam) with acetylacetone (Hacac) and diantipylmethane (dam) was incorporated into the microporous silica gel. With the polymerization of EMA, the hybrid material containing Tb(acac) 3·dam was obtained. The hybrid material exhibited good toughness and transparency and higher thermal stability than that of the pure complex and pure polymer matrix. In the range of doping concentration of Tb(acac) 3·dam (0.05%, 0.1%, 0.2%, 0.5%, 1.0%, 2.0% and 5.0%), emission intensity increases with the increasing of corresponding doping concentration and concentration quenching effect has not taken place.

Crystal Structure and Fluorescent Study of a Terbium(Ⅲ) Coordination Polymer

A novel Tb（Ⅲ） coordination polymer [Tb（bpapO2）2（NO3）3]n [bpapO2 = N2,N6- bi（pyridin-2-yl）pyridine-2,6-diamine-N,N＇-dioxide-dioxide] has been synthesized and it exhibits terbium’s characteristic fluorescent emission under UV radiation of 326 nm at room temperature. X-ray structural determination indicates that each terbium（Ⅲ） ion, centered in TbO8 core, connects to three adjacent coordinate centers via a bi-dentate ligand bpapO2, forming a one-dimensional coordination polymer. The compound crystallizes in the triclinic system, space group P1, with a = 11.2271（5）, b = 11.7997（5）, c = 14.8016（6） Ⅲ, α = 72.7060（10）, β = 89.9630（10）, γ = 66.7680（10）o, Z = 2, Dc = 1.822 g/cm3, V = 1705.14（13） Ⅲ3, F（000） = 932, the final R = 0.0340 and wR = 0.0669 for 4812 observed reflections with I 2σ（I）.

Simultaneous Determination of Trace Rare Earth Elements and Other Elements in High Purity Terbium Oxide (Tb_4O_7) by ICP-AES After HPLC Separation Using P507 Resin

This article describes a new method for the simultaneous determination of trace rare earth elements (REEs) and non rare earth elements (NREEs) in high purity terbium oxide by ICP-AES after HPLC separation using P507 resin. The chromatographic separation of the analytes from the matrix using dilute nitric acid as mobile phase was studied. The experimental results showed that a favorable separation of trace metals (Cu and Gd) from the matrix (Tb) can easily be achieved by elution with dilute nitric acid within 25 min. The proposed method was applied to the determination of trace metals (Ca, Cu, Mg, Mn, Ni, Si, La, Ce, Pr, Nd, Sm, Eu and Gd) in high purity terbium oxide. The detection limits (DLs) for the analytes ranged from 0.4-4.0 μg\5g -1, and the recoveries are from 78%-105%.

Synthesis, Crystal Structure and Fluorescence Properties of a Terbium(Ⅲ) Complex with Biphenyl-2,3,3’,5’-tetracarboxylic Acid

A new terbium complex based on biphenyl-2,3,3’,5’-tetracarboxylic acid(H4bptc) has been synthesized, {[Tb(Hbptc)(H2O)4]×H2O}n(1). Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analyses. Title complex crystallizes in monoclinic, space group P21/n with a = 14.090(2), b = 8.0824(13), c = 15.5591(17) A, V = 1775.4(5) A3, Mr = 576.22, Dc = 2.156 g/cm3, μ(Mo Kα) = 4.059 mm-1, F(000) = 1128, Z = 4, the final R = 0.027 and w R = 0.0726 for 3296 observed reflections(I > 2σ(I)). Complex 1 exhibits a 2 D layer structure, and such layers are further united together into a three-dimensional supramolecular structure through π···π interaction and intricate hydrogen bonding. The fluorescence excitation and emission spectroscopy of 1 showed that H4 bptc is a kind of highly efficient sensitizer for terbium(Ⅲ) ion. The title complex also displays efficient ligand sensitized luminescence in the visible region with long lifetime of 2.02 ms in the solid state.

A New Terbium(Ⅲ) Coordination Compound with 2-Thiophenecarboxylic Ligand:Synthesis and Crystal Structure

A new coordination compound with formula [Tb（2-TC）3（DMF）]n （1, 2-TC = 2-thio- phenecarboxylic ligand and DMF = dimethylformamide） was synthesized by solvothermal method. The structure of compound 1 was determined by single-crystal X-ray diffraction analyses, and characterized by elemental analyses, IR and powder X-ray diffraction. Structure analysis reveals compound 1, exhibiting a one-dimensional chain structure, crystallizes in triclinic space group P21/c, with a = 9.2751（19）, b = 16.490（3）, c = 15.865（5） A, β = 118.98（2）°, V= 2122.7（9）A3, D,. = 1.916 g/cm3, Mr= 612.45 （C18H15NO7S3Tb）, F（000） = 1196,μ（MoKa） = 3.67 mm-1, Z = 4, R = 0.0616 and wR = 0.0962 for 3865 observed reflections （I 〉 2o（I））, and R = 0.1092 for all data. Meanwhile, the photoluminescent properties of compound 1 were also investigated in the solid state at room temperature.

Synthesis and Characterization of Terbium-Trimesic Acid Luminescent Complex in Polyvinylpyrrolidone Matrix

Tb（Ⅲ ）-trimesic acid （TMA） luminescent complexes were synthesized in the polyvinylpyrrolidone （PVP） matrix. The elemental analysis, inductively coupled plasma-atomic emission spectroscopy （ICP-AES） and fourier-transform infrared spectroscopy （FT-IR） indicated that its chemical constitution is PVP/Tb（MTA）· 4H2O. The XRD patterns showed that the complex is a new kind of crystal. The TEM image indicates that the complex is rod shaped. The rod diameter is about 200 nm, and the length ranges from hundred of nanometer to a few micrometers. In addition, the dispersity is better. TG-DTA curves indicate that the complex is thermally stable before 463℃. Photoluminescence analysis indicates that the complex emits Tb^3＋ characteristic luminescence under ultraviolet excitation.