Luminescence of RE~(3+) and energy transfer from Gd~(3+) to RE~(3+) (RE = Dy, Eu) in SrGdAlO_4:RE~(3+)

Spectral properties of Gd3+, Dy3+ and Eu3+ ions in SrGdAlO4 are reported in detail. A cooperative vibronic transition of Gd3+ and the emission from the higher 5DJ (J=1, 2, 3) levels of Eu3+ were observed. Energy transfer occurs from Gd3+ to Dy3+ and to Eu3+. The influence of Gd3+ and Dy3+ concentrations on the luminescence intensity is discussed.     

Emission analysis of Sm(3+) and Dy(3+):MgLaLiSi(2)O(7) powder phosphors

This paper reports on the structural and emission properties of newly synthesized Sm(3+) and Dy(3+):MgLaLiSi(2)O(7) powder phosphors based on the measurement of their XRD, SEM, FTIR and photoluminescence spectra. Emission spectra of the Sm(3+):MgLaLiSi(2)O(7) phosphors with lambda(exci)=402 nm ((6)H(5/2)-->(4)F(7/2)) and Dy(3+):MgLaLiSi(2)O(7) phosphors with lambda(exci)=385 nm ((6)H(15/2)-->(4)I(13/2)) have been analyzed. Emission mechanisms of these phosphors have also been explained.     

Photoluminescence and energy transfer studies of Dy(3+)-doped fluorophosphate glasses

Dy(3+)-doped fluorophosphate glasses with composition (in mol%) (56-x/2)P(2)O(5)+17K(2)O+(15-x/2)BaO+8Al(2)O(3) + 4AlF(3)+ xDy(2)O(3), x=0.01, 0.05, 0.1, 1.0 and 2.0, have been prepared by melt quenching technique. The luminescence spectra and lifetimes of (4)F(9/2) level of Dy(3+) ions in these glasses have been measured using the 457.9 nm line of argon ion laser as an excitation source. The free-ion calculation and Judd-Ofelt analysis have been performed. The room temperature emission spectra corresponding to (4)F(9/2)-->(6)H(J) (J=7/2, 9/2, 11/2, 13/2 and 15/2) transitions of Dy(3+) ions were measured. The fluorescence decay from (4)F(9/2) level have been measured by monitoring the intense (4)F(9/2)-->(6)H(13/2) transition. The lifetime of the decay is obtained by taking the first e-folding times of the decay curves and is found to decrease with increase in Dy(3+) ions concentration due to concentration quenching. The decay curves are found to be perfectly single exponential for samples with low Dy(3+) ion concentration. The non-exponential decay curves observed for higher concentrations are well fitted to the Inokuti-Hirayama model for S=6, which indicates that the energy transfer between the donor and acceptor is of dipole-dipole nature. The energy transfer parameter and donor to acceptor interaction increases with Dy(3+) ions concentration due to increase of energy transfer from Dy(3+) (donor) to unexcited Dy(3+) (acceptor) ions.     

Emission analysis of Dy(3+):Ca(4)GdO(BO(3))(3) powder phosphor

Emission spectrum of Dy(3+):Ca(4)GdO(BO(3))(3) powder phosphor has been analyzed. Two emission bands at 492 and 588 nm with lambda(exci)=311 nm ((6)H(15/2)-->(4)L(19/2)) have been measured from this phosphor. For the intense yellow emission at 588 nm ((4)F(9/2)-->(6)H(13/2)), its lifetime has been measured. Emission performance of this phosphor has been explained in terms of an energy level diagram. Besides carrying out the emission analysis, XRD, SEM and FTIR studies have also been carried out in order to understand the nature and structural details of the optical material studied.     

EPR g factors of trigonal Dy(3+) center in ThO(2) crystal

The perturbation formulas of EPR g factors g(parallel) and g( perpendicular ) for the lowest Kramers doublet of 6H(15/2) of a 4f(9) ion in trigonal symmetry are established in this paper. In these formulas, besides the contribution due to the interaction within the lowest 6H(15/2) manifolds considered in the previous papers, the contributions due to the J-mixing among the 6H(15/2), 6H(13/2) (first excited state) and 6H(11/2) (second excited state) via crystal-field interaction, the admixtures among the states with the same J value via spin-orbit coupling interaction and those between the lowest Kramers doublet Gammagamma and other Kramers doublets Gamma(X) within the states 6H(J) (J=15/2,13/2,11/2) via crystal-field and orbital angular momentum interactions are included. From these formulas, the g factors g(parallel) and g( perpendicular ) for the trigonal Dy(3+) center in ThO(2) crystal are calculated. The results are discussed.     

异核高氯酸钐、镝在二苯亚砜体系中的共发光

合成了一系列异核高氯酸钐、镝二苯亚砜配合物：SmxDy1-x(DPSO)7(ClO4)(x=1.000-0.000,DPSO为二苯亚砜）。测定了配合物的组成、IR谱、荧光激发和发射光谱。荧光发射光谱表明：在二苯亚砜体系中Sm^3 对Dy^3 的发光有明显的猝灭作用,而Dy^3 对Sm^3 的发光有较强的敏化作用。根据配合物的荧光光谱计算了（Sm^3 、Dy^3 )及配体DPSO的有关能级,并研究了猝灭和敏化的机理。     

A study on hydrolytic polymerization of lanthanide ions

Experimental data of hydrolytic polymerization of lanthanide ions in aqueous solution were treated by graphic method, computer fitting and pq analysis, species present were ascertained and hydrolysis constants obtained. Ln (OH)²⁺ and Ln₂ (OH)₂⁴⁺ predominated in the species of all hydrolysis products. When the first and the second hydrolysis constants were plotted against radii and effective nuclear charge of lanthanide ions, the curves obtained conformed with the “three-division groups” rule. Correlation between hydrolysis constants of Ln₂ (OH)₂⁴⁺ and other hydrolysis constants is linear. Using the above empirical correlations we calculated hydrolysis constants of all lanthanide ions and obtained satisfactory results which showed good regularity for hydrolysis of lanthanide ions and thus systematized all data of the reaction.     

Studies on the Hydrolytic Behavior of Zirconium(IV)

The stability constants of zirconium(IV) hydrolysis species have been measured at 15, 25, and 35 °C [in 1.0 mol-dm^–3 (H,Na)ClO₄] using both potentiometry and solvent extraction. In addition, the solubility of [Zr(OH)₄(am)] has been investigated in a 1 mol-dm^–3 (Na,H)(ClO₄,OH) medium at 25 °C over a wide range of –log [H⁺] (0-15). The results indicate the presence of the monomeric species Zr(OH)³⁺, Zr(OH)₂ ²⁺, Zr(OH)₃ ⁺, and Zr(OH)₄ ⁰(aq) as well as the polymeric species Zr₄(OH)₈ ⁸⁺ and Zr₂(OH)₆ ²⁺. The solvent extraction measurements required the use of acetylacetone. As such, the stability constants of zirconium(IV) with acetylacetone were also measured using solvent extraction. All stability constants were found to be linear functions of the reciprocal of temperature (in kelvin) indicating that H ^o and S ^o are both independent of temperature (over the temperature range examined in the study). The results of the solubility experiments have shown four distinctly different solubility regions. In strongly acidic solutions, the solubility is controlled by the formation of polynuclear hydrolysis species in solution whereas in less acidic solution the formation of mononuclear hydrolysis species becomes dominant. The largest portion of the solubility curve is controlled by equilibrium with aqueous Zr(OH)₄ ⁰(aq) where the solubility is independent of the proton concentration. In alkaline solutions, the solubility increases due to formation of the zirconate ion. The middle region was used to determine the solubility constant (log *K _s10) of Zr(OH)₄(s). From the data in the alkaline region, a value of the stability of the zirconate ion has been determined. This is the first time that the possible evidence for the zirconate ion has been identified in aqueous solution that has previously been found only in the solid phase.     

Homoleptic rare-earth metal(III) tetramethylaluminates: structural chemistry, reactivity, and performance in isoprene polymerization

The complexes [Ln(AlMe4)3] (Ln=Y, La, Ce, Pr, Nd, Sm, Ho, Lu) have been synthesized by an amide elimination route and the structures of [Lu{(micro-Me)2AlMe2}3], [Sm{(micro-Me)2AlMe2}3], [Pr{(micro-Me)2AlMe2}3], and [La{(micro-Me)2AlMe2}2{(micro-Me)3AlMe}] determined by X-ray crystallography. These structures reveal a distinct Ln3+ cation size-dependency. A comprehensive insight into the intrinsic properties and solution coordination phenomena of [Ln(AlMe4)3] complexes has been gained from extended dynamic 1H and 13C NMR spectroscopic studies, as well as 1D 89Y, 2D 1H/89Y, and 27Al NMR spectroscopic investigations. [Ce(AlMe4)3] and [Pr(AlMe4)3] have been used as alkyl precursors for the synthesis of heterobimetallic alkylated rare-earth metal complexes. Both carboxylate and siloxide ligands can be introduced by methane elimination reactions that give the heterobimetallic complexes [Ln{(O2CAriPr)2(micro-AlMe2)}2(AlMe4)(C6H14)n] and [Ln{OSi(OtBu)3}(AlMe3)(AlMe4)2], respectively. [Pr{OSi(OtBu)3}(AlMe3)(AlMe4)2] has been characterized by X-ray structure analysis. All of the cerium and praseodymium complexes are used as precatalysts in the stereospecific polymerization of isoprene (1-3 equivalents of Et2AlCl as co-catalyst) and compared to the corresponding neodymium-based initiators reported previously. The superior catalytic performance of the homoleptic complexes leads to quantitative yields of high-cis-1,4-polyisoprene (>98%) in almost all of the polymerization experiments. In the case of the binary catalyst mixtures derived from carboxylate or siloxide precatalysts quantitative formation of polyisoprene is only observed for nLn:nCl=1:2. The influence of the metal size is illustrated for the heterobimetallic lanthanum, cerium, praseodymium, neodymium, and gadolinium carboxylate complexes, and the highest activities are observed for praseodymium as a metal center in the presence of one equivalent of Et2AlCl.     

Spectroscopic properties of Dy(3+) ions in NaF-B(2)O(3)-Al(2)O(3) glasses

This paper reports the optical properties of Dy(3+) in sodium fluoroborate glasses of the type XNaF.(89-X)B(2)O(3).10 Al(2)O(3).1Dy(2)O(3) (where X=8, 12, 16, 20 and 24). Judd-Ofelt intensity parameters (Omega(2), Omega(4), Omega(6)) are derived from the absorption spectra. The Judd-Ofelt theory has been applied to interpret the local environment of Dy(3+) ions and bond covalency of RE-O bond. These parameters have been used to calculate radiative transition probabilities (A(rad)), lifetimes (tau(R)) and branching ratios (beta(R)) for the excited level (4)F(9/2). The predicted values of tau(R) are compared with the measured values for (4)F(9/2) level for five glass compositions (Glass (A-E)). The stimulated emission cross-section sigma(lambda(P)) are also evaluated for the (4)F(9/2)-->(6)H(J) (J=11/2, 13/2, and 15/2) transitions.     

The Photophysical Properties of Quaternary Lanthanide (Eu3+, Tb3+, Sm3+, Dy3+) Functional Molecular Complexes

Summary. In this paper, according to the molecular fragment principle, a series of twelve quaternary luminescent lanthanide complex molecular systems were assembled. Both elemental analysis and infrared spectroscopy allowed to determine the complexes formula: Ln(Nic)₃(L)·H₂O, where Ln=Sm, Eu, Tb, Dy; HNic=pyridine-3-carboxylic acid; L=N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), pyrrolidone (pyro). The photophysical properties of these functional molecular systems were studied by recording both ultraviolet-visible absorption, phosphorescence, fluorescence excitation, and emission spectra. It was found that the conjugated pyridine-3-carboxylic acid acts as the main energy donor and luminescence sensitizer due to the suitable energy match and effective energy transfer to the luminescent Ln ³⁺ ions. Amide molecules (DMF, DMA, pyro) were only used as assistant structural ligands to enhance the luminescence. Especially the europium complexes show the strongest luminescence due to the optimum energy transfer between the HNic triplet state energy level and Eu³⁺.     

HPMBP和二苯胍对Ho~(3+)的协同萃取机理研究

研究了 1-苯基 - 3-甲基 - 4 -苯酰基吡唑酮 - 5(HPMBP)和二苯胍 (DPG)的三氯甲烷溶液对硝酸介质中Ho3+萃取机理。实验结果表明 :在体系Ho3+(～ 10 - 4mol/L)HNO3　NaNO3( μ =0 2 ) /HPMB -DPG -CH3Cl中 ,存在明显的协同效应。利用斜率法测得萃合物的组成为 [HB]+[HoA4 ](HA代表HPMBP ,B代表DPG) ,常温时的萃取平衡常数K =2 7.2 4 ;讨论了协同萃取机理和萃合物的结构。     

Ring-opening polymerization of lactones by rare-earth metal triflates and by their reusable system in ionic liquids

The ring-opening polymerizations (ROPs) of lactones catalyzed by rare-earth metal trifluoromethanesulfonates (triflates) (RE(OTf)₃) were examined. Among various complexes, scandium triflate (Sc(OTf)₃) emerged as an effective catalyst in toluene. The ROP of lactones by Sc(OTf)₃ proceeded in a living fashion, and the number of polymer molecules was controlled by the amount of protic additives such as benzyl alcohol and H₂O. In other words, one molecule of Sc(OTf)₃ catalytically produced a number of polymer molecules (up to 40 molecules) depending on the amount of protic additives. The plausible mechanism was depicted as an activated monomer mechanism. The polylactones with a number-average molecular weight over 25,000 were successfully synthesized. Immobilization of RE(OTf)₃ was investigated in three ionic liquids, and cerium triflate (Ce(OTf)₄) showed relatively high catalytic activity in a biphasic system of 1-butyl-3-methylimidazolium hexafluoroantimonate and toluene in the ROP of ?-caprolactone (CL). The ionic liquid containing Ce(OTf)₄ was used, at least three times, in the ROP of CL without losing catalytic activity.     

二乙三胺锌(Ⅱ)配合物对水解酶的模拟研究

研究了二乙三胺 (Dien)锌 (Ⅱ )配合物作水解酶模拟物催化对硝基苯酚醋酸酯 (NA)水解的动力学。结果表明 :催化水解速率对底物 (NA)及配合物 (ZnDien)浓度均呈一级反应 ,水解反应遵循速率方程dC/dt=(kobs[Zn Dien]+KOH[OH-]+… ) [NA],催化反应受酸碱平衡控制 ,催化机理与天然酶一致 ,表明了该项研究设计的配体和锌酶中配位环境与天然酶相似的特点。     

稀土固体超强酸SO_4~(2-)/TiO_2-La~(3+)催化合成尿囊素

尿囊素(1 脲基间二氮杂茂烷二酮—(2,4),allantoin)是一种两性化合物,可作为医药、化妆品、农业等化工原料中间体。通常用硝酸或过氧化氢氧化乙二醛生成乙醛酸后,再在酸催化下由乙醛酸与尿素缩合而成。但采用浓H2SO4、HNO3等作催化剂,产率偏低(<50%),选择性差,产品质量不好,同时设备腐蚀严重,污染环境。用SO2-4/MxOy型固体超强酸催化剂催化合成尿囊素[2 3],仍有产率偏低等不足之处。我们用La3+掺杂改性SO2-4/TiO2体系,合成了稀土固体超强酸催化剂SO2-4/TiO2 La3+,考察了合成尿囊素缩合反应的催化条件,在最适宜的反应条件下,催化…     

Heteroscorpionate rare-earth metal zwitterionic complexes: syntheses, characterization, and heteroselective catalysis on the ring-opening polymerization of rac-lactide

Novel neutral phosphine-modified heteroscorpionate ligand (3,5-Me(2)Pz)(2)CHPPh(2) (1) and its derivatives oxophosphine (2) and iminophosphine (3) heteroscorpionates were synthesized for the first time. These neutral heteroscorpionate ligands displayed unique chemistry towards rare-earth metal tris(alkyl)s [Ln(CH(2)SiMe(3))(3)(thf)(2)] (Ln=Y, Lu, Sc). The reaction between compound 1 and [Ln(CH(2)SiMe(3))(3)(thf)(2)] afforded heteroscorpionate rare-earth metal trialkyl adduct complexes 4a-c. Compounds 2 and 3 were treated with [Ln(CH(2)SiMe(3))(3)(thf)(2)] to give the unprecedented zwitterionic heteroscorpionate rare-earth metal dialkyls 5 and 6, respectively. In the process, the heteroscorpionates transferred to the carbanions by means of methine C-H bond cleavage that was attributed to the presence of the electron-withdrawing groups. In addition the ligand and central metal showed a concerted effect on both the catalytic activity and specific selectivity of complexes 4-6 for the ring-opening polymerization (ROP) of rac-lactide (rac-LA). All the adduct complexes 4 were nonselective and gave atactic polylactide (PLA), probably due to the dissociation of ligand 1 from the active metal center during the polymerization. Strikingly, zwitterionic complexes 5 catalyzed rapid ROP of rac-LA to produce PLAs with heterotacticity up to 0.87. However, the zwitterionic complexes 6 were less active and less selective than 5, which might be on account of the stronger coordination of the tetradentate ligand. Complexes 5 represent rare examples of the selective ROP of rac-LA mediated by rare-earth metal complexes supported by non-bisphenolate ligands.     

Studies on structural and electrical properties of transition metal ions (Mn, Co and Cu) co-doped Bi0.9Dy0.1FeO3 thin films

Effects of rare earth Dy and transition metal (TM = Cu, Co and Mn) ions co-doping on the structural, electrical and ferroelectric properties of the BiFeO₃ thin films prepared on Pt(111)/Ti/SiO₂/Si(100) substrates by using a chemical solution deposition method were investigated. All thin films formed as randomly oriented polycrystalline, with no detectable impurity or secondary phases. Among the thin films, the (Bi_0.9Dy_0.1)(Fe_0.975Mn_0.025)O₃ thin film exhibited well saturated hysteresis loops with remnant polarization (2P _r ) of 51 μC/cm² and low coercive electric field (2E _c ) of 685 at 935 kV/cm and low leakage current density of 1.4 × 10^?5 A/cm² at 100 kV/cm. The enhanced properties observed in the co-doped thin films could be considered as being the results of the suppression of ionic defects and of the modified microstructure.     

Hydrolytic polycondensation of alkoxysilanes and modification of polymerization reactions

Polymers having oxide network chains are produced by hydrolytic polycondensation of metal alkoxides and alkoxysilanes. Molecular morphology and molecular size distribution of these inorganic polymers are strongly affected by certain nonchemical parameters. Included among these parameters is the molecular separation of interacting species during the polymerization. There is strong evidence that the molecular size expansion occurs by two distinct processes: initially by a gradual “growth” process, and later by “recombination” of high-molecular weight species. The later process often leads to a bi-modal molecular size distribution. The concentration of water-rich siloxane solutions leads to significant molecular size expansion by further oxide network formation. No similar polymer size growth occurs during the concentration of alcohol based solutions. This difference in the polymeric activities can be related to the difference in the terminal bond under the two different conditions.     

Studies on the synthesis and thermal decomposition mechanisms of rare-earth metal (Pr,Nd, Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one

Three new rare-earth metal (Pr, Nd and Sm) salt hydrates of 3-nitro-1,2,4-triazol-5-one (NTO) were prepared and characterized. The thermal behaviour of the three salt hydrates, M(NTO)₃·nH₂O (M=Pr and Nd,n=9;M=Sm,n=8) were studied by means of TG and DSC under conditions of linear temperature increase. The thermal decomposition intermediates were determined by means of IR, MS and X-ray diffraction spectrometry. The thermal decomposition mechanisms of these hydrates were proposed as follows: We express our thanks to Professor Zhu Chunhua, Associate Professor Fu Xiayun, and Lecturers Fan Tao and Liang Yanjun for their help in this work.