三价铬离子水解聚合作用的研究 VII.反丁烯二酸存在下高铬浓度区水解产物的pqr分析

本文报道用静置平衡pH法研究在较高的铬浓度(CA=0.01, 0.015,0.02mol.dm^-^3)存在下,Cr^3^+在水溶液中的状态,用Newton-Raphson法和非线性Gauss-Newton法进行优化处理,自编成LEMIT程序、用此程序在电子计算机上对铬配合物HPMqAr的组成进行pqr分析,求得粒子的最佳组成为[CrOH]^2^+,[Cr~OH]^5^+,[Cr(OH)A]和[Cr~2(OH)A]^3^+.用此程序同时计算30个数据点,求得各粒子的水解常数,拟合结果良好,说明LEMIT程序能用于复杂体系的计算。     

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.     

Cr[3+]的水解聚合作用VI,反丁烯二酸存在下低浓度铬的水解聚合

铬(III)离子与反丁烯二酸生成的羟联多核配合物可用作偶联剂,但其在溶液中的状态尚缺乏定量研究。本文用静置平衡pH法在四种不同浓度(0.00175,0.0025,0.00375和0.005mol.dm[-8])的反丁烯二酸存在下和低铬浓度(0.0025mol.dm[-3])时,研究了Cr[3+]在溶液中的状态,并用New-ton-Raphson法和非线性最小平方法计算了在四种反丁烯二酸浓度下[Cr2OH][5+],[Cr2(OH)A][3+]和[Cr2(OH)A2][+]的水解常数和形成常数,在四种浓度下所得结果颇为一致。本文的结果对合成偶联剂和解释偶联作用的机理提供了线索。     

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.     

VUV spectroscopic properties of rare-earth (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE³⁺- activated (RE³⁺ = Sm³⁺, Eu³⁺, Tb³⁺ and Dy³⁺) Ba₆Gd₉B₇₉O₁₃₈ borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE³⁺-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm³⁺-activated BGBO, the charge transfer transition from O^2- to Sm³⁺ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm³⁺ f-f transitions of ⁴G_5/2 → ⁶H_J (J = 5/2, 7/2 and 9/2). The O^2--Eu³⁺ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu³⁺-doped BGBO. For Tb³⁺-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb³⁺, respectively. In addition, the absence of the f-d transitions of Sm³⁺ and Dy³⁺ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators.     

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.     

铕(Ⅲ)激活的磷酸镧发光性质研究

LaPO₄:Eu³⁺的发射光谱包含较强的Eu³⁺⁵D_o→⁷F₁跃迁发射和较弱的⁶D₁→⁷F₁跃迁发射。主发射峰583nm,对应于Eu³⁺5D_o→⁷F₁跃迁.通过对Eu³⁺的两种跃迁发射强度及荧光寿命和Eu³⁺浓度关系的测定和理论分析,探讨了发光中心Eu³⁺离子同的交叉弛豫和能量迁移机理。     

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.     

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。     

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⁺.     

Syndiotactic polymerization of styrene and copolymerization with ethylene catalyzed by chiral half-sandwich rare-earth metal dialkyl complexes

The syndiotactic polymerization of styrene(St) and the copolymerization of St with ethylene(E) were carried out by using a series of chiral half-sandwich rare-earth metal dialkyl complexes(Cp~x*) as the catalysts. The complexes are Ln(CH_2SiMe_3)_2(THF)(1-4: Ln = Sc(1), Ln = Lu(2), Ln = Y(3), Ln = Dy(4)) bearing chiral cyclopentadienyl ligand containing bulky cylcohexane derivatives in the presence of activator and AliBu_3. For the St polymerization, a high activity up to 3.1 × 10~6 g of polymer mol Ln~(-1)·h~(-1) and a high syndiotactic selectivity more than 99% were achieved. The resulting syndiotactic polystyrenes(sPSs) have the molecular weights(Mn) ranging from 3700 g·mol~(-1) to 6400 g·mol~(-1) and the molecular weight distributions(Mw/Mn) from 1.40 to 5.03. As for the copolymerization of St and E, the activity was up to 2.4 × 10~6 g of copolymer mol Sc~(-1)·h~(-1)·MPa~(-1), giving random St-E copolymers containing syndiotactic polystyrene sequences with different St content in the range of 15 mol%-58 mol%. These results demonstrate that the bulky cyclopentadienyl ligands of the chiral half-sandwich rare-earth metal complexes effectively inhibit the continued insertion of St monomers into the(co)polymer chain to some extent in comparison with the known half-sandwich rare-earth metal complexes.     

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.