YAG∶Ce体系中稀土离子掺杂对Ce3+的光谱性能的影响

采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln), 系统地研究了此体系中的Ln3+对Ce3+的发光强度的影响. 结果表明, 在YAG∶Ce的体系中, La3+, Gd3+, Lu3+等光学透明离子的少量掺杂对Ce3+的发光强度的影响不大; 掺入少量的Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+等稀土离子, 由于它们的能级与Ce3+的能级有交叠, 使它们之间存在着竞争吸收或能量转移, 对Ce3+的发光有较明显的变化, 其中, Pr3+和Sm3+的掺入使其在红光区有发射峰, 可以增加YAG∶Ce的红色成分以提高显色性; Nd3+, Eu3+和Yb3+对Ce3+的发光有严重的猝灭作用.     

Y2O2S∶Er3+，Yb3+的制备及Er3+离子在晶场中的能级分裂

采用沉淀法制备前驱体,通过不同温度合成了上转换发光材料Y2O2S∶Er3+,Yb3+,运用XRD,SEM和上转换发射光谱对其进行表征。结果表明,所合成的Y2O2S∶Er3+Yb3+属于六方晶系晶体,随着合成温度的升高,产物的粒径不断增大,上转换发射光强度逐渐增加。研究Y2O2S∶Er3+Yb3+的上转换发光过程,红光发射和绿光发射分别源于Er3+离子的4F9/2→4I15/2以及2H11/2→4I15/2,4S3/2→4I15/2能级跃迁。利用群论计算了晶场中Er3+离子的能级分裂数目。     

Er3+/Yb3+共掺纳米In2O3的制备及上转换发光

用低温溶剂热法以乙二醇为溶剂合成了Er3+和Yb3+共掺的In2O3纳米晶。用X射线衍射(XRD)、透射电镜(TEM)、漫反射光谱和上转换发光光谱对样品进行了分析。XRD和TEM结果表明,产物为纯的立方相In2O3结构,粒径约为30 nm;漫反射光谱显示了In2O3∶Er3+,Yb3+纳米晶在522、653和975 nm附近有3个吸收带;在980 nm近红外光激发下,样品发射出中心波长为525及555 nm的绿光和662 nm的红光,分别对应于Er3+的2H11/2→4I15/2、4S3/2→4I15/2和4F9/2→4I15/2跃迁;研究了Er3+和Yb3+离子的不同掺杂浓度对发光强度的影响,确定了Yb3+和Er3+离子的最佳掺杂浓度均为3%;双对数曲线显示绿光和红光的发射过程均为双光子吸收过程,对样品的上转换发光机制进行了初步讨论。     

Gd3+/Yb3+掺杂ZnO量子点作为双模式磁共振/CT成像探针

基于结合磁共振成像(MRI)的高空间分辨率和CT成像的深穿透能力设计思想,在乙醇溶液中水解醋酸锌、醋酸钆和醋酸镱,制备了油酸稳定的Gd3+/Yb3+掺杂ZnO量子点(ZnO∶Gd/Yb),并对其表面进行了氨基修饰。研究了ZnO∶Gd/Yb量子点的弛豫性能、X射线吸收性能、细胞毒性及体外MRI和CT成像。当Zn2+,Gd3+,Yb3+的摩尔比为1.0∶0.12∶0.20时,ZnO∶Gd/Yb量子点展现了最高的弛豫效率6.06 mmol/(L.s)对X-射线的吸收能力也显著高于临床CT造影剂碘比醇。体外MRI和CT成像实验表明,当Gd3+的浓度为1.5 mmol/L时,T1加权MRI信号明显增强,当Yb3+的浓度为5 g/L时,可呈现清晰的CT图像。细胞毒性实验表明,ZnO∶Gd/Yb量子点的浓度低于1.5 mmol/L(Gd3+)时,量子点的毒性相对较低。     

Nb+离子活化甲烷脱氢反应机理密度泛函(DFT)研究

通过DFT-UB3LYP方法, 计算了五重、三重和单重自旋态下的气相Nb+离子活化甲烷脱氢反应的能量变化, 并对其直接式和插入式反应机理进行了比较, 考察了自旋翻转对反应的影响. 结果表明, 插入式脱氢较直接式有利, CH4上的H转移到Nb+上形成的中间体HNbCH+3中, 多重度由五重降为三重, 反应活化能垒显著降低; HNbCH+3可经四中心过渡态转化为(H2)NbCH+2, 最后生成三重态的NbCH+2+H2. 速控步骤为(H2)NbCH+2的脱氢. 此外, 通过对V+, Nb+, Ta+活化甲烷的比较研究了三者活化甲烷的反应活性.     

龙眼叶片活性氧代谢和抗氧化系统对La3+的响应

以一年生龙眼小苗为材料,研究了La3+对龙眼叶片活性氧代谢和抗氧化系统的影响,探讨La3+提高植物抗逆境能力作用机制。龙眼小苗喷施10,20,30,40,50 mg.L-1的La(NO3)3两次,通过检测叶片的自由基含量、抗氧化酶活性和抗氧化物质含量来分析La3+提高龙眼抗氧化的作用。结果表明:20～30 mg.L-1La3+处理可明显清除龙眼叶片的.O2-和H2O2,减少MDA生成量;显著提高叶片SOD和CAT酶活性,降低POD活性,提高AsA-GSH循环运行效率及相关代谢酶APX,MDAR,DHAR和GR的活性,保证AsA和GSH再生,显示稀土离子La3+对龙眼抗性具有显著的正调节作用。     

镧、钆、镱三种稀土离子诱导背根神经元凋亡及膜上钾电流的比较研究

运用流式细胞仪和膜片钳技术研究La3+,Gd3+,Yb3+三种稀土离子诱导大鼠背根神经元DRG凋亡以及膜上钾离子通道的影响。结果表明:10,100,1000μmol.L-1LaCl3和GdCl3处理DRG神经元96 h,细胞不出现凋亡;YbCl3处理96 h,细胞的凋亡率明显递增。胞外La3+,Gd3+,Yb3+抑制瞬间外向钾电流IA,使IA的激活和失活过程都显著右移,抑制和右移的程度La3+最弱,Gd3+次之,Yb3+最强;胞内的La3+,Gd3+,Yb3+抑制延迟整流钾电流IK,抑制的程度也呈增长趋势。稀土离子在胞内外的结合位点不同;Yb3+较La3+和Gd3+的神经毒性强。     

298.16 K时Na+, Mg2+//Cl-, SO42-, NO3-, H2O体系中NaCl饱和区域相平衡

采用等温溶解平衡法研究了五元体系Na+, Mg2+//Cl-, SO42-, NO3-, H2O在298.16 K下氯化钠饱和平衡体系的溶解度, 获得了相应的投影干盐图、氯图和水图. 研究结果表明, 在298.16 K下氯化钠饱和时, 该五元体系投影干盐图由8个二盐共饱和的双变面、13条三盐共饱的单变线和6个四盐共饱的零变点构成, 存在两种复盐, 8个二盐共饱双变面分别对应于NaCl+NaNO3, NaCl+Na2SO4, NaCl+MgCl2·6H2O, NaCl+MgSO4·Na2SO4·4H2O, NaCl+Mg(NO3)2·6H2O, NaCl+NaNO3·Na2SO4·2H2O, NaCl+MgSO4·7H2O 和NaCl+MgSO4·(1—6)H2O. 讨论了该相图在新疆硝酸盐矿开发利用过程中的应用.     

γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物的合成与表征

利用缺位填充法合成了12个γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物K13[Ln(SiW10O36)2]·nH2O(Ln=La3+,Ce3+,Pr3+,Nd3+,Sm3+,Eu3+,Gd3+,Tb3+,Dy3+,Ho3+,Er3+,Yb3+).通过元素分析确定其组成,由红外光谱、紫外-可见吸收光谱、循环伏安及室温磁化率测定结果确认稀土离子与γ-[SiW10O36]8-相配位;183WNMR及荧光光谱结果则表明,稀土离子处于2个γ-[SiW10O36]8-构成的八配位环境中,标题化合物具有夹心型D2d对称性结构.     

KSrBP2O8:RE(RE=Eu2+,Tb3+,Eu3+)荧光粉的制备与发光性能研究

采用高温固相反应法制备了KSrBP2O8:RE(RE=Eu2+,Tb3+,Eu3+)系列荧光粉。利用X射线衍射仪对样品的物相结构进行了分析,结果表明:稀土离子的掺入没有改变荧光粉的主晶相。利用荧光光谱仪对样品的发光性能进行了测试,发现在近紫外光激发下掺杂Eu2+离子的样品具有宽带发射峰,最强发射位于450 nm左右,对应于Eu2+离子的4f65d1→4f7辐射跃迁。随着Eu2+掺杂量的增加,发射光从蓝光逐渐转变到蓝白光。另外,KSrBP2O8:Tb3+和KSrBP2O8:Eu3+能够在近紫外光激发下分别发射出绿光和红光,其最佳掺杂浓度分别为0.04%和0.08%(摩尔分数)。     

Magnetic properties of cyano-bridged Ln3+-M3+ complexes. Part I: trinuclear complexes (Ln3+ = La, Ce, Pr, Nd, Sm; M3+ = FeLS, Co) with bpy as blocking ligand

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(mu-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6].8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and pi-pi stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions.     

Magnetism of cyano-bridged Ln3+-M3+ complexes. Part II: one-dimensional complexes (Ln3+ = Eu, Tb, Dy, Ho, Er, Tm; M3+ = Fe or Co) with bpy as blocking ligand

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(mu-CN)2Ln(H2O)4(bpy)]n.4nH2O.1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe]n (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and pi-pi interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K.     

K5LnLi2F10(Ln=La,Gd, Y)的合成和Ce^3^+在其中的发光

在Ar气氛中, 采用高温固相反应法合成了K5LnLi2F10(Ln=La, Ce, Gd, Y)化合物,X射线衍射图表明: 除K5YLi2F10外, 均具有与K5NdLi2F10(KNLF)相同的结构。计算了K5LnLi2F10(Ln=Ln, Ce, Gd)的晶胞参数和晶胞体积, 它们随着La^3^+, Ce^3^+,Gd^3^+的离子半径减小而有规律地减小, 测定了K5CexLn1-xLi2F10化合物的激发光谱和荧光光谱, 发现Ce^3^+的激发波长和发射波长随着La^3^+, Gd^3^+, Y^3^+离子的改变几乎不变, 并对这种现象进行了讨论。     

镧系(Nd3+、Ho3+、Er3+)与1-苯基-3-甲基-4-三氟乙酰基吡唑酮-5和二安替吡啉甲烷三元配合物的研究

用分光光度法对镧系离子(Nd~(3+),Ho~(3+),Er~(3+))与1-苯基-3-甲基-4-三氟乙酰基吡唑酮-5(PMTFP)和二安替吡啉甲烷(DAM)水-乙醇溶液体系的研究以及对制备钕的相应配合物的元素分析证实:形成的三元配合物的的组成比为Ln~(3+):PMTFP:DAM=1:3:1。计算了相应配合物超灵敏跃迁的光吸收振子强度,并图示了它们之间的线性关系。研究了固态钕的三元配合物的红外吸收光谱和热稳定性。 镧系离子(Ln~(3+))同DAM和1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(PMBP)等β-二酮以及Ln~(3+)与PMTFP和三辛基磷氧化物(TOPO)的三元配合物的研究已有报导。本文报导了Ln~(3+)(Nd~(3+)、Ho~(3+)、Er~(3+))-PMTFP-DAM体系中的超灵敏跃迁现象与配位作用,以及Nd(Ⅲ)-PMTFP-DAM配合物的合成、组成和性质。     

两种磺酰胺类化合物的合成及其对Fe3+的氧化-还原荧光“开-关”性质

合成了两种磺酰胺类化合物, 并研究了其荧光性能. 通过它们对金属阳离子的选择性识别实验, 发现其在乙醇水溶液中均对Fe3+有专一性的识别作用, 并在NH2OH·HCl和H2O2的存在下, 两种化合物对Fe3+都具有氧化-还原荧光“开-关”作用.     

Colloidal nanoparticles of Ln3+-doped LaVO4: energy transfer to visible- and near-infrared-emitting lanthanide ions

Colloidal, organic solvent-soluble Ln3+-doped LaVO4 nanoparticles have been synthesized by a precipitation reaction in the presence of (C18H37O)2PS2- as ligand, that coordinates to the surface of the nanoparticles. The materials are well soluble in chlorinated solvent such as chloroform. Energy transfer of excited vanadate groups has been observed for Ln3+ ions that emit in the visible and the near-infrared (Eu3+, Tm3+, Nd3+, Er3+, Ho3+, Dy3+, Sm3+, Pr3+), thus making it a very generic sensitization mechanism. The LaVO4 nanoparticles have a different crystal structure than bulk LaVO4 ones (xenotime instead of monazite), similar to YVO4 nanoparticles. This xenotime crystal structure results in a more asymmetric crystal field around the Ln3+ ions that is advantageous to their luminescence, for it increases the radiative rate constant, thus reducing quenching processes.     

The solution structure of rhombic lanthanide complexes analyzed with a Model-free and crystal-field independent paramagnetic NMR method: application to nonaxial trimetallic complexes [LnxLu(3-x)(TACI-3H)2(H2O)6]3+ (x = 1-3)

The model-free approach has been extended with the derivation of a novel three-nuclei crystal-field independent method for investigating isostructurality in nonaxial (i.e., rhombic) complexes along the lanthanide series. Application of this technique to the heterotrimetallic sandwich complexes [LnLu2(TACI-3H)2(H2O)6]3+, which possess a single C2v-symmetrical paramagnetic center, unambiguously evidences isostructurality for Ln = Pr-Yb, while the variation of the second-rank crystal-field parameters and along the series prevents reliable structural analyses with the classical one-nucleus equation. Extension toward polymetallic magnetically noncoupled rhombic lanthanide complexes in [Ln2Lu(TACI-3H)2(H2O)6]3+ (two paramagnetic centers with Cs microsymmetry) and [Ln3(TACI-3H)2(H2O)6]3+ (three paramagnetic centers with C2v microsymmetry) requires only minor modifications of the original three-nuclei equation. Isostructurality characterizes [Ln2Lu(TACI-3H)2(H2O)6]3+ (Ln = Pr-Yb), while [Ln3(TACI-3H)2(H2O)6]3+ exhibit a structural change between Eu and Tb which results from the concomitant contraction of the three metallic centers. Particular attention has been focused on (i) the stepwise increase of contact (i.e., through-bond) and pseudocontact (i.e., through-space) contributions when the number of paramagnetic centers increases, (ii) the assignment of 13C resonances in the strongly paramagnetic complexes [Ln3(TACI-3H)2(H2O)6]3+ (Ln = Tb-Yb) for which reliable T1 measurements and [1H-13C] correlation spectra are not accessible, and (iii) the combination of crystal-field dependent and independent methods for analyzing the paramagnetic NMR spectra of axial and nonaxial lanthanide complexes.     

Synthesis and characterization of heterodinuclear Ln(3+)-Fe3+ and Ln(3+)-Co3+ complexes,bridged by cyanide ligand (Ln3+ = lanthanide ions). Nature of the magnetic interaction in the Ln(3+)-Fe3+ complexes

The reaction of Ln(NO3)3.aq with K3[Fe(CN)6] or K3[Co(CN)6] in N,N'-dimethylformamide (DMF) led to 25 heterodinuclear [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O and [Ln(DMF)4(H2O)3(mu-CN)Co(CN)5].nH2O complexes (with Ln = all the lanthanide(III) ions, except promethium and lutetium). Five complexes (Pr(3+)-Fe3+), (Tm(3+)-Fe3+), (Ce(3+)-Co3+), (Sm(3+)-Co3+), and (Yb(3+)-Co3+) have been structurally characterized; they crystallize in the equivalent monoclinic space groups P21/c or P21/n. Structural studies of these two families show that they are isomorphous. This relationship in conjunction with the diamagnetism of the Co3+ allows an approximation to the nature of coupling between the iron(III) and the lanthanide(III) ions in the [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O complexes. The Ln(3+)-Fe3+ interaction is antiferromagnetic for Ln = Ce, Nd, Gd, and Dy and ferromagnetic for Ln = Tb, Ho, and Tm. For Ln = Pr, Eu, Er, Sm, and Yb, there is no sign of any significant interaction. The isotropic nature of Gd3+ helps to evaluate the value of the exchange interaction.     

Simultaneous uptake of Ni2+, NH4+ and PO4(3-) by amorphous CaO-Al2O3-SiO2 compounds

Simultaneous uptake of Ni2+, NH4+, and PO4(3-) by amorphous CaO-Al2O3-SiO2 (C-A-S) compounds was investigated using batch and column methods. Fifteen different C-A-S samples with systematically varied chemical compositions were prepared by coprecipitation from ethanol-water solutions containing Ca(NO3)2.4H2O, Al(NO3)3.9H2O, and Si(OC2H5)4, using NH4OH as the precipitating agent. The resulting precipitates were dried and heated at various temperatures to produce the C-A-S samples, which were then characterized by XRD, FTIR, solid state MAS NMR, DTA-TG, and N2 adsorption. All the C-A-S samples prepared at 600-900 degrees C were amorphous, apart from the CaO-rich samples. Simultaneous uptake of Ni2+, NH4+, and PO4(3-) was determined by a batch method using a solution with an initial concentration of 2 mM. In these experiments, the uptake abilities of the C-A-S samples for Ni2+ and PO4(3-) were high, but were relatively low for NH4+. The uptake abilities for Ni2+ and PO4(3-) increased but that for NH4+ decreased as the silica content in the C-A-S decreased, suggesting that similar uptake mechanisms (ion substitution and/or precipitation) are operating for Ni2+ and PO4(3-), but the uptake mechanism for NH4+ is different (physical adsorption). The column experiments indicate that the order of uptake ability of C-A-S for the three ions is NH4+ < PO4(3-) < Ni2+. Although the silica content of the C-A-S does not have the expected influence on the uptake of these three ions, for NH4+ it plays an important role in the formation of the amorphous phase and also in the suppression of Ca2+ and/or Al3+ release from the C-A-S during the uptake experiments. The optimum uptake properties of the C-A-S can thus be controlled by adjusting the chemical compositions and heating conditions under which the samples are prepared.