Investigation of Ion-Binding Properties of Synthetic Polyelectrolytes with The Tb[III] Luminescence Probe

The binding properties of trivalent metal ions to polyelectrolytes were investigated through the use of Tb(III) luminescence studies. The condensation of Tb(III) with the homopolymers poly(acrylic acid) and poly(methacrylic acid) was studied in detail. In addition, the 1 : 1 copolymers of maleic acid with ethylene, isobutene, and 2,4,4-trimethyl-1-pentene were also examined. The emission intensity of the 305 nm Tb(III) hypersensitive excitation band was found to correlate with the size of the alkyl group on the polymer chains. Tb(III) luminescence lifetime studies indicated that the metal ion binding site was equivalent over a wide range of Tb(III)/polymer ratios. The number of solvent molecules coordinated by Tb(III) in the various polymer complexes was determined and found to range between 3.5 and 4 molecules of water of hydration.     

Tb(III) Speciation in Human Blood Plasma by Computer Simulation

With the wide application of rare earth fertilizer and medicines1, more and more rare earths enter into environment, and also into human body via food chain. Now it is very urgent to study the biological effect of rare earths on human health and environment. After entering into human body by whatever route, lanthanide ions are transported to secondary deposition sites mainly via the plasma in the blood stream. So it is very important to study lanthanides speciation in human blood plasma. Becau…     

Fluorescence lifetime of terbium(III) as a probe for the ion-binding properties of tactic poly(methacrylic acids)

The binding properties of trivalent metal ions to polyelectrolytes were investigated through the use of terbium [Tb(III)] in fluorescence studies. The fluorescence intensity and lifetimes of the lanthanide ions are directly dependent upon the number of water molecules bound to their inner coordination sphere. The more efficiently a ligand coordinates to a lanthanide ion, the more water molecules are expelled and consequently, the greater the fluorescence intensity and lifetime. This effect was used to probe for differences in the complexation behavior of tactic polymers. Aqueous solutions of isotactic and syndiotactic poly(methacrylic acid) (PMA) were neutralized and complexed with Tb(III) ions. The fluorescence intensity of the 286 nm hypersensitive excitation band was monitored and the lifetimes were measured using several excitation wavelengths. It was found that the isotactic PMA/Tb(III) complex exhibited a six times greater fluorescence intensity than the syndiotactic PMA complex. Lifetime measurements gave the number of water molecules coordinated by Tb(III) in the isotactic complex to be 2.4 while 3.4 waters remained bound to the Tb(III) ion in the syndiotactic PMA complex. These results indicate that isotactic PMA has the greater binding affinity towards Tb(III) ions. © 1997 John Wiley & Sons, Inc.     

Study on interaction between Tb(III) and poly(N-isopropylacrylamide)

A new kind of the thermo-sensitive and fluorescent complex of poly(N-isopropylacrylamide) (PNIPAM) and Tb(III) was synthesized by free radical polymerization, in which PNIPAM was used as a polymer ligand. The complex was characterized by using X-ray photoelectron spectroscopy (XPS), ultraviolet-visual (UV), Fourier transform infrared (FT-IR) and fluorescence spectroscopy. The results from the experiments indicated that there is a strong interaction between PNIPAM and Tb(III), leading to a decrease in the electron density of nitrogen and oxygen atoms and an increase in the electron density of Tb(III) in the PNIPAM containing Tb(III) by contrast with PNIPAM and Tb(III), respectively, meanwhile, exhibiting that the Tb(III) is mainly bonded to oxygen atoms in the polymer chain of PNIPAM and formed the complex of PNIPAM-Tb(III). After forming the PNIPAM-Tb(III) complex, the emission fluorescence intensity of Tb(III) in the PNIPAM-Tb(III) complex is significantly enhanced because the effective intramolecular energy transfer from PNIPAM to Tb(III). Especially, the emission intensity of the fluorescence peak at 547 nm can be increased as high as 145 times comparing with that of the pure Tb(III). The intramolecular energy transfer efficiency for fluorescence peak at 547 nm can reach as high as 68%. The fluorescence intensity is related the weight ratio of Tb(III) and PNIPAM in the PNIPAM-Tb(III) complex. When the weight ratio is 1.4%, the maximum fluorescence enhancement can be obtained. Nevertheless, the lower critical solution temperature of PNIPAM containing a low content of Tb(III) has not obviously changed after the formation of the complex of PNIPAM-Tb(III) by the interaction between PNIPAM and Tb(III). This novel thermosensitive and fluorescence characterization of the PNIPAM-Tb(III) complex may be useful in the fluorescence systems and the biomedical field.     

Tb(III)‐modified properties of thermosensitive core–shell microspheres

A novel functional complex with the thermosensitive, magnetic, and fluorescent properties of poly(N‐isopropylacrylamide)‐grafted poly(N‐isopropylacrylamide‐co‐styrene) (PNNS) microspheres and Tb(III), PNNS–Tb(III), has been synthesized and characterized with different techniques. When PNNS with a core–shell structure interacts with Tb(III), Tb(III) mainly bonds to oxygen of the carbonyl groups of PNNS, forming the novel PNNS–Tb(III) complex. PNNS shows antiferromagnetic behavior, whereas the PNNS–Tb(III) complex exhibits paramagnetic behavior. The saturation magnetization is approximately 50 times higher than that of PNNS. The fluorescence intensity of the PNNS–Tb(III)complex at 545 nm is enhanced as much as 223 times in comparison with that of pure Tb(III). The novel magnetic and fluorescent properties of the PNNS–Tb(III) complex may be useful in biomedicine and fluorescence systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3121–3127, 2006     

温度对铽（III）-转铁蛋白溶液构象的影响

在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N’-2-乙磺酸（Hepes）条件下,铽 （III）与N,N’-二（2-羟苄基）乙二胺-N,N’-二乙酸（HBED）结合并发生交换 相互作用使铽（III）荧光增强10~4倍,通过监测铽（III）545 nm荧光强度的变化 测定了Tb-HBED配合物的条件稳定常数是lgK = 14.30 ± 0.49;Tb-HBED配合物中 配体、铽（III）荧光强度均随着温度的升高而降低。在pH 7.4,0.01 mol/L Hepes条件下,Tb_N-apoTf-Tb_C配合物中蛋白质的荧光强度随着温度的升高而降 低,而能量受体铽（III）的荧光强度随着温度的升高而增强,主要源于铽（III） 与螺旋5色氨酸残基间的无辐射能量转移;当温度由0 ℃上升到55 ℃时,平均能量 转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起 Tb_N-apoTf-Tb_C配合物大的构象变化;铽（III）与人血清脱铁转铁蛋白的结合使 蛋白质的变性温度降低。同样条件下,Tb_N-apoOTf-Tb_C配合物与Tb_N-apoTf- Tb_C配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽（ III）荧光强度没有明显的增强;铽（III）对蛋白质的变性温度几乎没有影响。     

Columinescence effect in macromolecular complexes of Eu(III) and Tb(III)

The effect of Y(III) and Gd(III) coactivator ions on the intensity of Eu(III) and Tb(III) luminescence in monomer and polymer mixed-metal complexes was studied. Isomorphic replacement of Eu(III) and Tb(III) ions by Y(III) and Gd(III) ions in macromolecular complexes led to sensitization of Eu(III) and Tb(III) ion luminescence. A mechanism of columinescence was suggested. It involves a charge transfer and the ligand orbitals and the vacant orbitals of Eu(III) and Tb(III) ions and coactivators.     

Tb(III)与PNIPAM接枝核壳纳米微球相互作用的研究

利用透射电镜、X射线光电子能谱、动态激光光散射和荧光光谱技术对Tb(III)与聚N-异丙基丙烯酰胺(PNIPAM)接枝核壳纳米微球PNIPAM-g-P(NIPAM-co-St) (PNNS)的相互作用进行了研究. 结果表明: Tb(III)和热敏性的核壳纳米微球PNNS有显著的相互作用. 其一, Tb(III)可与PNNS中酰胺基团上的氧原子配位形成微球配合物Tb(III)-PNNS; 其二, Tb(III)-PNNS微球配合物兼具热敏性; 其三, 该配合物在545 nm处的荧光强度较Tb(III)增大了233倍, Tb(III)与PNNS分子间能量传递达到50%, 当Tb(III) 质量分数为12%时荧光强度最大.     

Visible-light sensitisation of Tb(III) luminescence using a blue-emitting Ir(III) complex as energy-donor

In Ir(III)/Tb(III) dyads in which the excited state energy of the Ir(III) unit lies above 22,000 cm(-1), visible-light excitation of the Ir(III) chromophore results in sensitised emission from Tb(III) following Ir → Tb energy-transfer.     

Lanthanide luminescence sensing of copper and mercury ions using an iminodiacetate-based Tb(III)-cyclen chemosensor

The design, synthesis and photophysical evaluation of 1.Tb.Na, a Tb(III)-cyclen-based sensor, possessing a phenyl iminodiacetate-based receptor, for the selective detection of Cu(II) and Hg(II) ions in water is demonstrated. Sensitisation of the Tb(III) ⁵D₄ excited state was achieved by excitation of the phenyl receptor, which in water gave rise to a characteristic time-delayed and line-like Tb(III) emission. The Tb(III) emission was shown to be pH independent over the physiological pH window. The changes in the Tb(III) emission were monitored by carrying out metal titrations using various groups I, II and transition metal ions. Of these, only the titrations of Cu(II) and Hg(II) gave rise to modulations in the Tb(III) emission; resulting in quenching in the Tb(III) emission by ca. 65% and 40%, respectively.     

Study on interaction between Tb(III) and poly(N-isopropylacrylamide)-g-poly(N-isopropylacrylamide-co-styrene) core-shell nanoparticles

Based on the synthesis of poly(N-isopropylacrylamide-co-styrene) P(NIPAM-co-St) and poly(N-isopropylacrylamide) (PNIPAM) grafted P(NIPAM-co-St) core-shell nanoparticle, a new kind of thermoresponsive and fluorescent complex of Tb(III) and PNIPAM-g-P(NIPAM-co-St) (PNNS) was successfully prepared. The PNNS-Tb(III) complex was characterized with the different techniques. It was found that when PNNS with the core-shell structure interact with Tb(III), Tb(III) mainly bonded to O of the carbonyl groups of PNNS, forming the novel PNNS-Tb(III) complex. After forming the complex, the emission fluorescence intensity of Tb(III) in the complex is significantly enhanced. Especially, the maximum emission intensity of the PNNS-Tb(III) complex at 545 nm is enhanced about 223 times comparing to that of the pure Tb(III) because the effective intramolecular energy transfer from PNNS to Tb(III). The intramolecular energy transfer efficiency from PNNS to Tb(III) reaches 50%. The fluorescence intensity is related the weight ratio of Tb(III) and PNNS in the PNNS-Tb(III) complex. When the weight ratio of Tb(III) and the PNNS is 12 wt%, the enhancement of the emission fluorescence intensity at 545 nm is highest. This novel fluorescence characterization of the PNNS-Tb(III) complex may be useful in the fluorescence systems and the biomedical field.     

一种吡啶酰胺类配体与Tb(Ⅲ)配位模式的探讨

研究了Tb(Ⅲ)对配体N,N-二(2-羧基苯基)-2,6-吡啶二甲酰胺(BCPD)的乙醇溶液的荧光滴定光谱,结果发现滴定过程中两者之间可能存在两种结合模式[(BCPD)_2Tb和(BCPD) Tb]。通过进一步研究配体BCPD的荧光发射光谱和时间扫描荧光分析Tb(Ⅲ)的特征光谱,从不同角度证明了两种不同配位模式的存在并分析了原因。研究结果进一步丰富和完善了稀土有机配合物的配位理论,对荧光材料的制备具有一定指导意义。     

Intensity-tunable micelles and films containing bimetal ions—europium(III) and terbium(III)

In this paper, multicolored micelles were prepared by coordination of lanthanide(III) (europium(III) (Eu(III)) and terbium(III) (Tb(III))) ions with block copolymer in different molar ratios of n _Eu(III)/n _Tb(III). The micelles formed by polymer–Eu(III)/Tb(III) could emit higher quantum yield luminescence than the mixture of polymer–Eu(III) micelles and polymer–Tb(III) micelles. The micelles containing Eu(III) and Tb(III) could emit a yellow-green color, and the intensity varied with the molar ratios of n _Eu(III)/n _Tb(III). In the constant concentrations of Eu(III) and 1,10-phenanthroline (Phen), the intensity of ⁵D₀→⁷F₂ increased with the addition of Tb(III), and the intensity of ⁵D₄→⁷F₅ decreased with the increasing of Eu(III) in the constant concentrations of Tb(III) and Phen. All the multicolored micelles could be spin-coated as intensity-tunable films.     

Application of long-lived luminescence for detection in liquid chromatography

Summary Quenched and sensitized lanthanide luminescence as detection in liquid chromatography has been investigated. An important advantage in comparison with phosphorescence is that the long-lived luminescence as applied does not require deoxygenation of the samples. In order to obtain a high luminescence intensity Tb(III) complexes with acetylacetonate have been formed, after which indirect excitation of Tb(III) can be realized via the ligands. The potential of Tb(III) luminescence as a detection method in ion chromatography has been shown for chromate, which is an efficient quencher. Sensitizing of the Tb(III) luminescence has been applied for thiol-containing analytes. These compounds are derivatized with maleimidyl salicylic acid to complexes that sensitize the Tb(III) luminescence. From a comparison of the results obtained with normal fluorescence detection and time-resolved sensitized Tb(III) luminescence detection it has become clear that the last method has a higher sensitivity, but in particular a higher selectivity.     

Cyano-bridged terbium(III)-chromium(III) bimetallic quasi-one-dimensional assembly exhibiting long-range magnetic ordering

A new cyano-bridged Tb(III)-Cr(III) heterometallic complex [Tb(H(2)O)(2)(DMF)(4){Cr(CN)(6)}]·H(2)O (DMF = dimethylformamide) (1), assembled from paramagnetic hexacyanochromium(III) [Cr(CN)(6)](3-) building block and highly anisotropic terbium(III) ion has been prepared and structurally and magnetically characterized. Complex 1 shows one-dimensional (1D) zig-zag chain-like structural motif which is further extended into three-dimensional network through hydrogen-bonding interactions. The long-range magnetic ordering observed in complex 1, which is possibly due to interchain magnetic dipolar interactions, illuminates that this complex is a molecule-based magnet with critical temperature of about 5 K. This higher critical temperature among those of Ln(III)-Cr(III) heterometallic complexes exhibiting long-range magnetic ordering is probably due to the introduction of highly anisotropic terbium(III) ion.     

Neodymium, gadolinium, and terbium complexes containing hexafluoroacetylacetonate and 2,2'-bipyrimidine: structural and spectroscopic characterization

Lanthanide complexes of the form Ln(hfa)3bpm (where Ln=Nd(III), Gd(III), or Tb(III); hfa=1,1,1,5,5,5-hexafluoroacetylacetone and bpm=2,2'-bipyrimidine) have been structurally characterized. The Nd and Gd complexes form one-dimensional arrays when X-ray-quality crystals are grown by the slow evaporation of concentrated solutions of the complexes. Each metal is 10-coordinate with repeating Ln-bpm units. The Tb complex does not form a one-dimensional array under these conditions. Its structure is 9-coordinate with the ninth position occupied by a covalently bonded water molecule that is hydrogen-bonded to the bpm group from another complex in solution. Luminescent studies show that the Nd complex undergoes nonradiative relaxation through solvent vibrational deactivation, while the lowest excited state of the Gd complex, 6P7/2, is higher in energy than the T1 state of the hfa ligand, making luminescence improbable for both of these complexes. In contrast, the Tb complex emits in the visible region of the spectrum when solutions of the complex are excited at 304 nm associated with the pi-pi* transition of the hfa ligand. Emission lines corresponding to transitions from the 5D4 state to the 7FJ manifold of the Tb(III) are observed. The intensity of these emissions decreases as temperature is increased. Lifetime measurements of the Tb monometallic complex fit to a monoexponential with the lifetime decreasing as the temperature is increased.     

Protein-mediated efficient synergistic "antenna effect" in a ternary system in d(2)o medium

A ternary system consisting of a protein, catechin (either + or - epimer), and Tb(III) in suitable aqueous buffer medium at physiological pH (= 6.8) has been shown to exhibit highly efficient "antenna effect". Steady state and time-resolved emission studies of each component in the binary complexes (protein with Tb(III) and (+)- or (-)-catechin with Tb(III)) and the ternary systems along with the molecular docking studies reveal that the efficient sensitization could be ascribed to the effective shielding of microenvironment of Tb(III) from O-H oscillator and increased Tb-C (+/-) interaction in the ternary systems in aqueous medium. The ternary system exhibits protein-mediated efficient antenna effect in D(2)O medium due to synergistic ET from both the lowest ππ* triplet state of Trp residue in protein and that of catechin apart from protection of the Tb(III) environment from matrix vibration. The simple system consisting of (+)- or (-)-catechin and Tb(III) in D(2)O buffer at pH 6.8 has been prescribed to be a useful biosensor.     

Probing metal binding in the 8-17 DNAzyme by TbIII luminescence spectroscopy

Metal-dependent cleavage activities of the 8-17 DNAzyme were found to be inhibited by Tb(III) ions, and the apparent inhibition constant in the presence of 100 microM of Zn(II) was measured to be 3.3+/-0.3 microM. The apparent inhibition constants increased linearly with increasing Zn(II) concentration, and the inhibition effect could be fully rescued with addition of active metal ions, indicating that Tb(III) is a competitive inhibitor and that the effect is completely reversible. The sensitized Tb(III) luminescence at 543 nm was dramatically enhanced when Tb(III) was added to the DNAzyme-substrate complex. With an inactive DNAzyme in which the GT wobble pair was replaced with a GC Watson-Crick base pair, the luminescence enhancement was slightly decreased. In addition, when the DNAzyme strand was replaced with a complete complementary strand to the substrate, no significant luminescence enhancement was observed. These observations suggest that Tb(III) may bind to an unpaired region of the DNAzyme, with the GT wobble pair playing a role. Luminescence lifetime measurements in D(2)O and H(2)O suggested that Tb(III) bound to DNAzyme is coordinated by 6.7+/-0.2 water molecules and two or three functional groups from the DNAzyme. Divalent metal ions competed for the Tb(III) binding site(s) in the order Co(II)>Zn(II)>Mn(II)>Pb(II)>Ca(II) approximately Mg(II). This order closely follows the order of DNAzyme activity, with the exception of Pb(II). These results indicate that Pb(II), the most active metal ion, competes for Tb(III) binding differently from other metal ions such as Zn(II), suggesting that Pb(II) may bind to a different site from that for the other metal ions including Zn(II) and Tb(III).     

Amine-templated polymeric lanthanide formates: synthesis, characterization, and applications in luminescence and magnetism

The novel polymeric formates of general formula [(Fmd)Ln(III)(HCOO)(4)](∞) (Fmd(+) = NH(2)-CH(+)-NH(2); Ln = Eu (1), Gd (2), Tb (3), Dy (4)] were synthesized through solvothermal methods in formamide solutions. The compounds are isotructural; they crystallize in the orthorhombic C222(1) chiral space group. The coordination geometry at the metal centers is square antiprismatic (coordination number eight), with each formate ligand bridging adjacent lanthanide ions. The overall negative three-dimensional (3D) framework charge is balanced by the formamidinium cations sitting inside the channels along the a axis, forming extensive N-H···O hydrogen bonding with the surrounding cage. All the compounds have been characterized through single-crystal/powder X-ray diffraction, IR spectroscopy, and TG-MS analysis. Finally, their luminescence and magnetic properties have been assessed, leading to remarkable emission intensities, especially for the Tb(III) compound (Φ = 0.83), with corresponding lifetime decays in the micro (Dy) and millisecond (Tb, Eu) time scale. A weak but sizable antiferromagnetic interaction has been observed for the Gd(III) derivative.     

Synthesis of Eu(III) and Tb(III) complexes with novel pyridine dicarboxamide derivatives and their luminescence properties

A novel ligand, N2,N6-bis[2-(3-methylpyridyl)]pyridine-2,6-dicarboxamide (L2) and the corresponding Eu(III) and Tb(III) hydrochlorate complexes have been synthesized and characterized in detail based on elemental analysis, IR and NMR. The crystal and molecular structure of the complexes was determined by X-ray crystallography. The Eu(III) and Tb(III) ions were found to coordinate to the amido nitrogen atoms and pyridine nitrogen atoms. The luminescence properties of lanthanide complexes in solid state, in different solutions and in different pH value were investigated. The result shows that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes, and the ligand (L2) is an excellent sensitizer to Tb(III) ion.