Modified dipicolinic acid ligands for sensitization of europium(III) luminescence

The effect of substitution at the 4 and 3,5 positions in the pyridine ring of europium(III) pyridine-2,6-dicarboxylate complexes has been investigated with particular emphasis on sensitization of the Eu3+ ion. Sensitization of the Eu3+ 615-nm emission was achieved through excitation of the ligands in which the 4 substituent was -H, -OH, and -Cl and the 3,5 position was -H. In these cases, the ligand-to-Eu3+ ratio was confirmed as being 3:1. The sensitization was found to increase following substitution of the 4 position in the order Cl > H > OH. This is attributed to energy transfer occurring from the ligands into different Eu3+ intra-atomic energy levels, with spin selection rules governing the efficiency of this process. The Eu3+ luminescence lifetime was measured and found to vary from 1.16 to 2.90 ms depending on the excitation energy, ligand, and solvent. For the case of the 3,5-dibromo-4-hydroxy derivative, no sensitization was observed and a ligand-to-Eu3+ ratio of 1:1 was found. The solubility of these complexes in water and their long emission lifetime make them attractive for use as probes in biological systems.     

2,2'-bipyridine lariat calixcrowns: a new class of encapsulating ligands forming highly luminescent Eu3+ and Tb3+ complexes

A new class of calix[4]arene crown ethers with one or two bipyridines appended to the polyether ring (lariat calixcrowns) have been designed and synthesized; the luminescence properties of their Eu3+ and Tb3+ complexes have been studied in acetonitrile. In this solvent, long lifetimes for the metal emitting states and high metal-luminescence intensities obtained upon ligand excitation have been observed in both Eu3+ and Tb3+ complexes. The association constants in methanol have been determined for some of the complexes studied.     

YTaO4：Gd,Eu体系光致发光中的能量传递

Yttrium orthotantalate co doped by Eu 3+ and Gd 3+ has been synthesized by solid state method. The emission and excitation spectra of YTaO4: Gd, Eu are studied in detail. In the excitation spectra of Eu 3+5D 0→ 7F2 transition emission in YTaO4:Gd, Eu, there appear excitations of Gd3+ and TaO43- group, which indicate energy transfer from Gd 3+ and TaO4 3- group to Eu 3+ in the process of luminescence. The excitation spectra of Gd 3+ emission(λ=312 5 nm) including strong excitation of charge transfer of group show energy transfer from host lattice to Gd 3+ . So there are two ways of energy transfer in YTaO4:Gd,Eu system. The strong evidences from excitation spectra, emission spectra and diffusive reflection spectra of this system show that Gd 3+ can play an intermediate role in the process of luminescence. There is energy transfer from TaO 3- 4 to Gd 3+ and finally to Eu 3+ via the charge transfer state and spectral overlap. The energy transfer from TaO 3- 4 to Gd 3+ is a dominating process in this system.     

冠醚取代蒽醌超分子体系的设计与合成及分子内能量转移的研究

大环冠醚由于其自组装性能及分子识别能力而引起人们广泛的重视.近来,冠醚又成为在超分子体系中用于建构主体分子的一种重要的建造单元^[1~4].Costa^[5]等曾报道苯并冠醚与被识别的稀土离子铕(Ⅲ)与铽(Ⅲ)之间的能量传递过程,选择性激发冠醚主体观察到稀土离子的发光.由于二氮杂冠醚与稀土离子能形成更稳定的配合物^[6].我们利用了冠醚分子的分子识别能力及蒽醌分子的光敏性,设计合成了一种新的氮杂冠醚取代蒽醌分子(图1)(以下文中用代号AQ-CW表示),并以该分子作为主体分子,以稀土离子作为客体构成超分子体系,研究超分子体系内的能量转移过程.     

双核铕(Ⅲ)配合物的合成及选择性激发

成功地合成一种新的四齿配体2,5-二(4-((2-吡啶-1氢-苯并[d]嘧唑)甲基)苯基)-1,3,4-噁二唑(L),并且将该配体作为第二配体合成出双核Eu3+配合物[Eu(TTA)3]2L(TTA二2-噻吩三氟甲基乙酰丙酮),配合物[Eu(TTA)3]2L的结构用红外光谱,吸外-可见吸收光谱进行了充分表征.为了讨论配...     

吡啶吡唑基配体C8-BPP对硝酸溶液中Am3+和Eu3+的萃取

合成了吡啶吡唑基配体C8-BPP[2,6-bis（5-（n-octyl）-1H-pyrazol-3-yl）pyridine],并采用红外光谱、核磁共振波谱、质谱等手段对其进行了表征.以正十二烷为稀释剂,2-溴己酸为协萃剂,研究了C8-BPP从HNO₃溶液中萃取Am³⁺和Eu³⁺的行为.重点考察了萃取时间、酸度和萃取剂浓度等对分配比D和分离因子SF_Am/Eu的影响.在HNO₃浓度为0.2~1.0 mol/L时,C8-BPP萃取Am³⁺和Eu³⁺的D值随HNO₃浓度增加而减小,SF_Am/Eu值先增大后减小;HNO₃浓度为0.5 mol/L时,SF_Am/Eu达到55.随着配体浓度的增加,C8-BPP萃取Am³⁺和Eu³⁺的D值均增加,SF_Am/Eu值缓慢减小,但仍在40以上.斜率分析表明,C8-BPP萃取Am³⁺和Eu³⁺均形成了1： 1型的萃合物.还采用紫外滴定、高分辨质谱、红外光谱、拉曼光谱和时间分辨荧光光谱等方法研究了C8-BPP与Eu³⁺的配位化学行为,并得到了配合物的组成和稳定常数.     

GdVO_4∶Eu~(3 )的真空紫外激发光谱研究

报道了GdVO4∶Eu3 的光致发光光谱和真空紫外 紫外激发光谱。GdVO4∶Eu3 是高效率的真空紫外 紫外激发荧光材料。GdVO4∶Eu3 在6 0～ 35 0nm真空紫外 紫外波段的激发可能主要来源于基质的吸收 ,有明显的Eu3 及Gd3 的 4fn - 1 5d吸收。在GdVO4∶Eu3 中 ,存在如下能量传递过程 :VO3 - 4 →Eu3 ,Gd3 →Eu3 ,Gd3 →VO3 - 4 →Eu3 ;通过后两个过程 ,Gd3 Eu3 可实现量子剪裁。     

Optical properties and valence change of europium ions in a sol-gel Al2O3-B2O3-SiO2 glass by femtosecond laser pulses

The Al2O3-B2O3-SiO2 glass containing europium ions was prepared by a sol-gel method. Fluorescence line-narrowing spectra (FLN) indicate two different environments of the Eu 3+ ions. The calculated second crystal-field parameters exhibit the opposite behaviors of the two different environments. The FLN excitation and emission spectra before and after irradiation show that the change of the emission mainly comes from the Eu 3+ ions at site I, revealing that the concentration ratio of the Eu 3+ ions at site I to site II was decreased. The emission spectra confirmed that some Eu 3+ ions were reduced into Eu 2+ ions. The excitation spectra indicate that the Eu 3+ ions at the sites with higher covalence degree can be easily reduced, implying that the Eu 3+ ions are more easily reduced at site I than at site II. The absorption spectra before and after irradiation exhibit that the absorption of Eu 2+ ions increases and that the positive hole centers appear. These results suggest a mechanism of the formation of the Eu 2+ ions by femtosecond laser irradiation.     

蒽醌冠醚铕离子络合物分子内能量转移

研究了蒽醌冠醚及其铕离子络合物的光物理性质 .研究结果表明 ,选择性激发铕离子络合物中的蒽醌冠醚能发生分子内能量转移 ,观察到铕离子的发光 .荧光衰减测试表明由于冠醚的包络作用使得铕离子络合物的荧光寿命较未络合铕离子的寿命有所延长 .向蒽醌冠醚铕离子络合物的甲基四氢呋喃溶液中加入水后 ,其荧光强度明显减弱 ,这说明了蒽醌冠醚对铕离子的络合作用不完全 ,未能有效地阻挡水和溶剂对铕离子的影响 .     

铕离子在乙二醇低聚物中的配合作用与电化学行为

研究了乙二醇低聚物（ＰＥＧ）与Ｅｕ（２＋）及Ｅｕ（３＋）所形成配合物的结构，荧光性质和电化学行为．Ｅｕ（３＋）的配合物是由ＥｕＣｌ３溶于具有不同摩尔质量的ＰＥＧ而成的．它们在３９４ｎｍ和６１４ｎｍ处分别有很强的激发和发射光谱峰，并且这两峰的强度随着ＰＥＧ的摩尔质量的增大而加强．Ｅｕ（２＋）的配合物是通过用涂布有氧化铟及氧化锡的玻璃板作为工作电极，在氮气气氛下，加－２Ｖ（ｖｓＡｇ）电压还原ＥｕＣｌ３的ＰＥＧ溶液来制备的．它们的荧光性质和１８—Ｃ—６冠醚与Ｅｕ（２＋）所形成配合物的性质非常接近，从而表明ＰＥＧ的化学环境与大环聚醚配体的很相似．进一步的红外与荧光谱实验结果表明：铕离子不但与聚乙二醇的末端－ＯＨ基团结合，而且亦能与链中间的氧原子作用．随着聚合物分子量的增大，铕离子的点对称性不断下降．Ｅｕ（３＋）在聚合物中的氧化还原很不可逆．添加支持盐对其电化学行为有很大影响．     

YTao4：Nb，Eu的发光性能研究

用高温固相反应法合成了铌酸根NbO^3-4和Eu^3 共掺杂的正钽酸盐化合物Y1－xEuxTa1-yNbyO4,研究该体系中紫外光和X射线激发下的发光性能,研究表明,在紫外光激发下,YTaO4:Nb,Eu是一种比较有效的红色发光材料,激发能可以通过NbO^3 4离子传递给Eu^3 ,随钽酸盐中NbO^3-4基团浓度的增中,化合物的结构从M'型YTaO4变成褐钇铌型YNbO4结构,它的发光性质也随之改变。     

Sr2SiO4:Eu3+发光材料的制备及其光谱特性

采用溶胶-凝胶法制备了Sr2SiO4:Eu3+发光材料. 测量了Sr2SiO4:Eu3+材料的激发与发射光谱, 发射光谱主峰位于618 nm处;监测618 nm发射峰时, 所得激发光谱主峰分别为320、397、464 和518 nm. 研究了Sr2SiO4:Eu3+材料在618 nm的主发射峰强度随Eu3+浓度的变化情况. 结果显示, 随Eu3+浓度的增大, 发射峰强度先增大; 当Eu3+浓度为7%时(x), 峰值强度最大; 而后随Eu3+浓度的增大, 峰值强度减小. 在Eu3+浓度为7%的情况下, 研究了电荷补偿剂Li+的掺杂浓度(x(Li+))对Sr2SiO4:Eu3+材料发射光谱强度的影响. 结果显示, 随x(Li+)的增大, 材料发射光谱强度先增大后减小, 当x(Li+)为8%时, 峰值强度最大.     

Li_2O－Ln_2O_3－SiO_2：Eu~（3＋），Bi~（3＋）体系的结构

采用ｓｏｌ－ｇｅｌ法合成了系列发光体Ｌｉ２Ｏ－Ｌｎ２Ｏ３－ＳｉＯ２：Ｅｕ３＋，Ｂｉ３＋，并确定了发光体的物相结构．当Ｌｎ３＋＝Ｙ３＋和Ｌｎ３＋＝Ｌａ３＋时，紫外光激发下Ｅｕ３＋的发射分别以红光和橙光为主，只存在一种Ｅｕ３＋发光中心；Ｌｎ３＋＝Ｇｄ３＋时，至少存在两种Ｅｕ３＋发光中心和两种Ｂｉ３＋发光中心（共掺杂Ｅｕ３＋，Ｂｉ３＋），Ｂｉ３＋的吸收和发射所处的能量位置最低，４ｆ格位的Ｂｉ３＋发生了向Ｅｕ３＋的有效能量传递．     

Mild Hydrothermal Synthesis and Optical Properties of the Complex Fluoride KMgF_3 Doped with Eu

Perovskite complex fluorides have attracted great interests due to their particular physical properties such as antiferromagnetic characteristics1, photoluminescence behavior2. Complex fluorides are usually prepared by solid state reactions at high-temperature. In spite of inert atmosphere, it is inevitable to contain a bit of oxygen. This has great effect on the luminescent character of rare earth ions. There are also reports about synthesizing some binary fluorides by high-temperature hy…     

Ca3La3(BO3)5中Eu3+的光致发光

本文详细地研究了紫外光激发下,Ca_3La_3(BO_3)_5中Eu~(3+)的发光光谱和激发光谱与组成、结构的关系.发现Eu~(3+)在此基质中可能不止一个发光中心;Eu~(3+)自身浓度猝灭的机理为电四极-四极相互作用.     

Photoluminescence characterization of Ca10Na(PO4)7:Eu3+ red-emitting phosphor

Eu3+-doped Ca10Na(PO4)7 phosphors were successfully synthesized by solid-state reaction techniques. Their structures and photoluminescence characteristics were carefully studied. An efficient red emission under near-ultraviolet excitation is observed. The maximum intensity of luminescence was observed at the Eu3+ concentration around 9 mol%. The quadrupole-quadrupole interaction between Eu3+ ions is the dominant mechanism for concentration quenching of fluorescence emission from Eu3+ ions in Ca10-xNa(PO4)7:xEu3+. Due to the excitation spectrum is well coupled with near UV light, Ca10-xNa(PO4)7:xEu3+ phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes.     

CaAl12O19基质中Eu2+-Cr3+的能量传递与发光性质

在还原气氛下高温固相法合成了CaAl12O19:Eu2+,Cr3+荧光粉.样品光谱显示:Eu2+发射带与Cr3+吸收带有重叠,具备Eu2+-Cr3+之间发生能量传递必要条件.在290 nm近紫外光激发下,单掺杂Eu2+和Cr3+时样品均无691 nm发射,仅在Eu2+,Cr3+共掺时才出现691 nm发射,这证明Eu2+和Cr3+之间发生了能量传递,且监测691 nm时样品的激发光谱也证实了这一点.CaAl12O19:1%Eu2+,x%Cr3+样品组的发射光谱研究表明:增大x能提高Cr3+红光与Eu2+蓝紫光发射强度之比及Eu2+-Cr3+之间能量传递效率.CaAl12O19:2%Cr3+,x%Eu2+样品组的激发光谱分析表明:x>2时,Cr3+在415 nm处的吸收效率相对于565 nm有显著提高.还对样品CaAl12O19:1%Eu2+,1%Cr3+荧光寿命和能量传递速率进行了简单分析.     

新型铕,铽(Ⅲ)三元配合物的合成、表征及发光性能

采用Claisen缩合反应设计合成了β-二酮配体1-(4-溴苯)-4,4,4-三氟丁烷-1,3-二酮(BPT),并合成了相应的新型稀土Eu,Tb(Ⅲ)三元配合物。通过元素分析、1H NMR谱、红外光谱、紫外光谱、荧光光谱和磷光光谱技术对合成的产物进行了表征和分析。红外光谱分析表明:BPT中存在着酮式-烯醇式互变;配合物中的稀土离子与BPT中的氧原子以及Phen中的氮原子形成了配位键。紫外光谱表明配合物主要是由第一配体BPT吸收能量。荧光光谱显示Eu(BPT)3Phen的发光强度较大,进一步的研究表明,BPT的最低三重态能级与Eu3+的5D0能级匹配较好。     

BaY2F8∶Ce, Eu中Ce3+→Eu2+的能量传递和Ce3+→Eu3+的电子转移

采用高温固相反应法制备了 Ba Y2 F8∶ Ce3 + ,Ba Y2 F8∶ Eu2 + 和 Ba Y2 F8∶ Ce,Eu,测定了它们的激发、发射和漫反射光谱 .首次发现并研究了在 Ba Y2 F8共掺 Ce F3 和 Eu F3 体系中存在 Ce3 + → Eu2 + 的能量传递和Ce3 +→ Eu3 +的电子转移两种过程及其竞争 .根据光谱数据 ,讨论了 Ce4 +的可能取代格位     

稀土掺杂氟化镁钾纳米晶的合成及其光谱特性

采用微乳液法合成了Eu²⁺,Ce³⁺单掺和双掺KMgF₃纳米晶,分析了样品的结构与形态. 结果表明,所合成的样品均为单相,颗粒粒度分布均匀. 讨论了光谱特性并与高温固相法合成的产物作了对比. 研究发现,在KMgF₃纳米晶双掺体系中,由于Eu²⁺和Ce³⁺竞争吸收激发能,只能观察到Ce³⁺的发射带; 而在KMgF3多晶共掺体系中,因为存在Ce³⁺→Eu²⁺能量传递过程,只能观察到Eu²⁺的发射峰.