Europium(III)-chelates embedded in nanoparticles are protected from interfering compounds present in assay media

Lanthanide chelates are excellent labels in ligand binding assays due to their long lifetime fluorescence, which enables efficient background reduction using time-resolved measurement. In separation-free homogeneous assays, however, some compounds in the sample may cause quenching of the lanthanide fluorescence and extra steps are required before these samples can be measured. In this study we have evaluated whether europium chelates packed inside a polystyrene nanoparticle are better protected from the environment than individual Eu(III)-chelates, and do these particles have higher tolerance against known interfering compounds (bivalent metal ions and variation of pH). We also tested whether metal ions had any effect on a fluorescence resonance energy transfer (FRET) based detection of a bioaffinity binding reaction. The presence of metal ions or variation of pH did not affect the fluorescence of the Eu(III)-chelate dyed nanoparticles, while significant decrease of the fluorescence was detected with a 9-dentate Eu(III)-chelate. Metal ions also decreased the fluorescence lifetime of the 9-dentate Eu(III)-chelate from 0.960 to 0.050 ms. Coloured metal ions caused a minor decrease in sensitised emission generated by FRET when Eu(III)-chelate dyed nanoparticles were used as donor labels. The decreased signal was due to the absorption of the sensitised emission by the coloured metal ions, since the metal ions had no effect on the lifetime of the sensitised emission. Thus the Eu(III)-chelate dyed nanoparticles are preferred labels in homogeneous bioaffinity assays, when interfering compounds are known to be present.     

在空气中合成MBPO5:Eu2+和MBPO5:Yb2+(M=Ca,Sr,Ba)荧光体

以含RE₂O₃(RE=Eu, Yb)为起始物, 在空气中成功地合成了MBPO5:RE(²⁺)(M=Ca, Sr, Ba;RE(²⁺)=Eu(²⁺), Yb(²⁺))荧光体, 测定了它们的激发和发射光谱峰位以及发射半高宽.     

Synthese und Kristallstruktur von ACu4As2 (A: Ca–Ba,Eu)

Synthesis and Crystal Structure of A Cu₄As₂ ( A : Ca–Ba, Eu) Steel‐gray single crystals of ACu₄As₂ with A = Ca–Ba and Eu respectively were synthesized by heating mixtures of the elements at about 900 °C. Structure determinations with X‐ray diffractometry data revealed, that the isotypic compounds crystallize in the rhombohedral CaCu₄P₂ type structure (R3m; Z = 3) (hexagonal axes see ”︁Inhaltsübersicht”︁”︁). Measurements of the susceptibility of EuCu₄As₂ showed divalent Eu and ferromagnetic order at 35 K.     

Sensitization of uranium fluorescence using 2,6-pyridinedicarboxylic acid: Application for the determination of uranium in the presence of lanthanides

The 2,6-pyridinedicarboxylic acid (PDA) has been shown to efficiently sensitize and enhance the fluorescence of uranium in aqueous medium. Interestingly, this ligand stabilizes the UO₂²⁺ species, which without the ligand is known to be in a negligible concentration, in aqueous medium at pH 6. The ligand sensitized enhancement of UO₂²⁺ fluorescence by PDA, provides an analytical tool for the determination of uranium at trace levels, in aqueous medium. Furthermore, PDA is also known to enhance the fluorescence of lanthanides; consequently, the simultaneous determination of uranium and lanthanides, using PDA as a fluorescence sensitizing agent, becomes a possibility, which has been demonstrated in this work. We have shown that the use of PDA yields detection limits of 2.2×10⁻⁷ M for UO₂²⁺, 1×10⁻⁸ M for Tb³⁺ and 5×10⁻⁹ M for Eu³⁺ in the simultaneous determination of these analytes.     

铕(Ⅲ)-呋喃甲酸配合物的光谱表征

以硝酸铕 ,呋喃甲酸和邻菲咯啉 (phen)合成了配合物 [Eu(FA) 3·2H2 O]·NO3(4 ,4’ Hbpy) ,[Eu(FA) 3·phen]H2 O和Eu(FA) 2 ·NO3·phen。用元素分析、红外吸收光谱、紫外吸收光谱和溶液荧光光谱对配合物进行了组成确定和表征。溶液荧光光谱表明 ,配合物 [Eu(FA) 3·2H2 O]·NO3(4 ,4’ Hbpy)的发光强度比混配配合物Eu(FA) 2 ·NO3·phen和 [Eu(FA) 3·phen]H2 O的发光强度小很多 ,而且发光寿命较短 ,三元配合物 [Eu(FA) 3·phen]H2 O的发光强度比四元配合物Eu(FA) 2 ·NO3·phen的发光强度略大     

含稀土铕(Ⅲ)配位聚合物的研究Ⅰ.铕(Ⅲ)-噻吩甲酰三氟丙酮-聚(苯乙烯-丙烯酸)的结构表征

研究了铕 (Ⅲ )和噻吩甲酰三氟丙酮 (HTTA)形成的有机配合物与聚 (苯乙烯 丙烯酸 )PSAA在不同pH值时发生配位反应得到配位聚合物NaEu(Ⅲ ) TTA PSAA的 3种样品 (a) ,(b) ,(c)。红外光谱、紫外光谱、X光电子能谱的测试表明了Eu3 分别与PSAA ,TTA- 发生配位。元素分析和电导率测定结果证明了配位组成和结构在不同的 pH条件下发生变化。结果表明 ,配合物试样 (a) ,(b) ,(c)中Eu3 的含量分别为11 89% ,12 5 5 % ,13 4 1%。     

2-噻吩乙醛酸-邻菲罗啉-铕配合物的合成、结构表征及荧光性能的研究

合成了铕与 2 噻吩乙醛酸 (HL)和邻菲罗啉 (phen)的配合物 ,用元素分析、电导率、红外光谱和核磁共振谱测定了配合物的分子式为 [EuL2 phen·(H2 O) 3 ]NO3 ;配合物中的Eu(Ⅲ )离子与 2 噻吩乙醛酸和水分子中的O原子以及邻菲罗啉中的N原子配位。在室温下测定了配合物的激发和发射光谱 ,配合物中Eu(Ⅲ )离子的5D0 7F1和5D0 7F2 跃迁分别位于 5 92和 6 18nm。该固体配合物于室温下被紫外光激发可以发出强的特征红色荧光。IR光谱中 ,2 噻吩乙醛酸的特征吸收峰νCO (1719cm-1) ,νC—O(12 32cm-1) ,δO—H(90 9cm-1)在形成配合物后消失。在配合物中出现—COO-的反对称νas(16 4 2cm-1)和对称νs(14 0 8cm-1)伸缩振动吸收峰。在1HNMR谱图中 ,2 噻吩乙醛酸环上的 3个氢原子的化学位移形成配合物后移向高场 ,邻菲罗啉环上 4种不同环境的质子峰的化学位移形成配合物后向低场移动。从TG曲线可以看出 ,此配合物在常温至 2 5 0℃以下是稳定的。     

Fluoridhaltige Gäste in Alumosilicaten: Tetrafluoroborate in dem Sodalithen Na8Al6Si6O24(BF4)2

In the course of investigations on optical properties resulting from the interaction of fluorides with alumosilicate host materials and rare earth guests, a well defined BF₄^– ion wasfound to be incorporated within the sodalite of composition Na₈Al₆Si₆O₂₄(BF₄)₂. The resulting cubic molecular structure, which was determined by Rietveld methods (space group P4 n, a = 906.91 pm, wRp = 0.045, Rp = 0.027), contains one anion in each sodalite cage and is, contrarily to expectations, thermally stable. NMR spectroscopic investigations indicated a fast rotatory motion of the BF₄^– tetrahedra at room temperature and agreed with the tetrahedral BF₄^– ions found in IR and Raman spectra. Preliminary attempts to obtain a luminescent material by incorporation of Eu³⁺ through aqueous ion exchange only yielded low rare earth concentrations, giving rise to characteristic red emission lines at 581 nm (⁵D₀ → ⁷F₁) and 615 nm (⁵D₀ → ⁷F₂) in a 1:2 intensity ratio. The material unexpectedly exhibited a strong broad band emission at 520 nm after calcination under Ar, which is attributed to the formation of an Eu²⁺ species. Further calcination under air partially reestablished the Eu³⁺ emission.     

Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing β‐Diketone and Schiff Bases

The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)₃]; Hpta=1,1,1‐trifluoro‐5,5‐dimethylhexane‐2,4‐dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H₂saltn), bis[5‐(tert‐butyl)salicylidene]trimethylenediamine (H₂(^tBu)saltn), or bis(salicylidene)cyclohexane‐1,2‐diyldiamine (H₂salchn), and the corresponding Zn^II complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)₃] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a ^tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)₃]. The luminescence spectrum of [ZnB] showed a band around 450 nm. The intensity decreased in the presence of [Eu(pta)₃], reflecting complexation between [Eu(pta)₃] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)₃Zn(saltn)], [Eu(pta)₃Zn{(^tBu)saltn}], and [Eu(pta)₃Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log , where =[[Eu(pta)₃ZnB]]([[Eu(pta)₃]][[ZnB]])^?1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)₃Zn(salchn)] revealed the strongest luminescence at 613 nm. The results of X‐ray diffraction analysis for [Eu(pta)₃Zn(saltn)] showed that Zn^II had a coordination number of five and was bridged with Eu^III by three donor O‐atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta.