Synthesis, crystal structure and fluorescence of a new europium complex with 2-bromobenzoate and 2,2′-bipyridine

A new complex of {[Eu2(2-BrBA)6(2,2'-bpy)2]2.CH3CH2OH·H2O} (2-BrBA=2-bromobenzoate; 2,2'-bpy=2,2'-bipyridine) was prepared by solvent method and characterized with X-ray single-crystal diffraction, IR spectroscopy, UV spectrscopy, and fluorescence spectroscopy. The complex crystallized in triclinic crystal system, PT space group, with a=1.17196(4) nm, b=-2.36142(9) nm, c=2.59151(9) nm, a=113.266(2)°, β=101.100(2)°, and γ=94.400(2)°. Two independent dinuclear molecules were contained in the asymmetric unit. The two molecules were similar to each other. Each Eu(Ⅲ) ion was nine-coordinated with seven oxygen atoms from five 2-BrBA ligands and two ni-trogen atoms from 2,2'-bpy molecule. The carboxylate groups acted as bidentate-chelating, bidentate-bridging and chelating-bridging coor-dination modes. The complex adopted a distorted monocapped square-antiprism coordination geometry. Five peaks at 579, 591, 613, 652,and 697 nm appeared in the fluorescence spectrum, corresponding to 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transition emis-sions of the Eu(Ⅲ) ion, respectively.     

Europium binding to humic substances extracted from deep underground sedimentary groundwater studied by time-resolved laser fluorescence spectroscopy

Humic substances (HSs) are ubiquitous in various environments including deep underground and play an important role in the speciation and mobility of radionuclides. The binding of Eu³⁺, a chemical homologue of trivalent actinide ions, to HSs isolated from sedimentary groundwater at ?250 m below the surface was studied by time-resolved laser fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) as a function of pH and salt concentration. PARAFAC modeling reveals the presence of multiple factors that correspond to different Eu³⁺ species. These factors resemble those observed for Eu³⁺ binding to HSs from surface environments; however, detailed comparison shows that there are some particularities in Eu³⁺ binding to the deep groundwater HSs. The distribution coefficients (K_d) of Eu³⁺ binding to the HSs calculated from the PARAFAC modeling exhibits a rather strong salt effect. At 0.01 M NaClO₄, the K_d values are relatively large and comparable to those to the surface HSs; they are decreaed at 0.1 M NaClO₄ by more than an order of the magnitude. The K_d values are larger for the humic acid fraction of the deep underground HSs than the fulvic acid fraction over the entire range of pH and salt concentration investigated in this study.     

EVA/铕配合物薄膜的制备及光学性能研究

通过溶液浇铸法将四元铕配合物掺杂到乙烯醋酸乙烯酯（EVA）中交联固化得到EVA复合膜,优化了制备EVA膜时固化温度、固化时间和引发剂加入量等工艺条件。通过紫外可见光光谱、荧光光谱研究了EVA复合膜的光学性能。结果表明,配合物在EVA中均匀分散;其掺杂量为1 %时,EVA复合膜具有良好的可见光透过率,对200~400 nm的紫外光有强吸收,并且能够发射出较强的红色荧光。     

The separation of europium from a middle rare earth concentrate by combined chemical reduction,precipitation and solvent-extraction methods

The chemical reduction of pure europium(III) chloride solutions was investigated using reagents comprising reactive metals (Zn and Mg), metal amalgams (Zn-Hg, Na-Hg and Eu-Hg), metal hydride (NaBH₄) and nitrogenous reductants (N₂H₄ and NH₂OH). Using 100% excess of reducing agent and of ammonium sulphate, efficient precipitation of europium(II) sulphate was obtained with the metal amalgams (99·7–99·9%) and with zinc metal (99·8%), whereas only partial precipitation was obtained with magnesium metal (69%), and no precipitation was observed with the other reagents. Application of the method to synthetic rare earth chloride solutions containing europium 7·5, neodymium 5, samarium 35 and gadolinium 20 g dm⁻³ gave efficient precipitation of europium(II) sulphate with zinc and europium amalgams, but no selective precipitation with sodium amalgam. Reduction of an authentic middle rare earth chloride solution with zinc amalgam gave 97·5% recovery of europium(II) sulphate containing (as a percentage of the total rare earths) europium 92, samarium 3·5, neodymium 2, cerium 1, praseodymium 0·6 and gadolinium 0·5%. Conversion of the europium(II) sulphate to europium(II) chloride, followed by re-precipitation of the sulphate increased the europium content only to 96·5%, whereas replacement of the re-precipitation by solvent extraction of the trivalent rare earth impurities into solutions of commercial organophosphorus or carboxylic acids in xylene increased the europium content to > 99·98%. The zinc ions introduced into the middle rare earth mother liquor during the reduction procedure can be removed by solvent extraction into a commercial phosphine oxide (Cyanex 925), without loss of rare earth values.     

萃取分离-石墨炉原子吸收光谱法测定氧化钐和氧化铕中痕量钴

研究了高纯稀土氧化物中钴的测定方法。实验表明,在pH3左右,用吡咯烷二硫代氨基甲酸铵(APDC)络合钴,MIBK萃取分离,有机相与水相之比1∶6时,萃取率最高,用石墨炉原子吸收光谱法测定氧化钐和氧化铕中钴。主要共存离子不干扰,相对标准偏差分别为9.0%和9.3%,氧化钐和氧化铕中钴的加标回收率分别为95%～100%和95%～108%。     

Preparation and luminescence properties of europium complex with a-naphthylacetic acid incorporated in silica matrix by sol-gel method

Europium ternary complex of Eu (NNA)3(NNA=o-naphthylacetic acid) was embedded in silica matrix at different ratios by sol-gel method. The luminescence properties of silica composites were studied by comparing them with those of corresponding pure complex by means of excitation, emission spectra and lifetimes. The fluorescence lifetime was prolonged when the pure complex was incorporated in silica matrix. The relative fluorescence intensity and fluorescence lifetimes increased simultaneously with the increase of Eu(NNA)3.     

红色荧光粉Ba_3La_6(SiO_4)_6:Eu~(3+)的制备与发光性能

采用高温固相法合成了Eu~(3+)激活的Ba_3La_6(SiO_4)_6红色荧光粉并对其发光性质进行了研究。XRD谱显示,合成样品为纯相Ba_3La_6(SiO_4)_6晶体。样品的激发光谱由一系列宽谱组成,峰值分别位于300、364、384、395、416和466nm,其激发主峰位于395nm。在395nm激发下,荧光粉在619nm(~5D_0→~7F_2)处有很强的发射。研究了不同Eu~(3+)掺杂浓度对样品发射光谱的影响。结果显示,随Eu~(3+)掺杂量的增大,发光强度先增大后减小。Eu~(3+)掺杂摩尔分数为13%时,出现浓度淬灭,其浓度淬灭机理为电偶极-电偶极相互作用。研究了不同Bi~(3+)掺杂量对Ba_3La_6(SiO_4)_6:Eu~(3+)发射光谱及色坐标的影响。Bi~(3+)掺杂样品中存在Bi~(3+)→Eu~(3+)的能量传递。     

聚酰亚胺/醋酸铕杂化材料的制备与光谱研究

用傅立叶变换红外光谱和紫外-可见吸收光谱对制备的醋酸铕(Eu(Ac)3)与聚酰亚胺(PI)杂化材料(PI/Eu(Ac)3)进行了表征,结果表明,Eu3 离子与聚酰亚胺中的O,N发生配位;用XRD分析结果显示,PI/Eu(Ac)3杂化材料为无定形态,且Eu(Ac)3未团聚形成晶相。该材料综合了无机材料和有机材料的性能互补,在光学,电学,磁学,平板显示等领域有着广阔的应用前景。     

Plasma-electrochemical synthesis of europium doped cerium oxide nanoparticles

In the present study,a plasma-electrochemical method was demonstrated for the synthesis of europium doped ceria nanoparticles.Ce(NO3)3· 6H2O and Eu(NO3)3·5H2O were used as the starting materials and being dissolved in the distilled water as the electrolyte solution.The plasma-liquid interaction process was in-situ investigated by an optical emission spectroscopy,and the obtained products were characterized by complementary analytical methods.Results showed that crystalline cubic CeO2:Eu3+ nanoparticles were successfully obtained,with a particle size in the range from 30 to 60 nm.The crystal structure didn't change during the calcination at a temperature from 400℃ to 1000℃,with the average erystallite size being estimated to be 52 nm at 1000℃.Eu3+ ions were shown to be effectively and uniformly doped into the CeO2 lattices.As a result,the obtained nanophosphors emit apparent red color under the UV irradiation,which can be easily observed by naked eye.The photoluminescence spectrum further proves the downshift behavior of the obtained products,where characteristic 5Do → 7F1,2,3 transitions of Eu3+ ions had been detected.Due to the simple,flexible and environmental friendly process,this plasma-electrochemical method should have great potential for the synthesis of a series of nanophosphors,especially for bio-application purpose.