共查询到20条相似文献,搜索用时 15 毫秒
1.
A solvent extraction method withTBP as an extractant was used for the determination of the stability constantsK
1
o
for the SmNO
3
2+
complex, for different least approach distanceså of ions. It was established thatå=6.5 Å for SmNO
3
2+
.
Zur Assoziation von Nitrat-Ion mit Sm3+
Zusammenfassung Die StabilitätskonstantenK 1 o für den SmNO 3 2+ -Komplex bei verschiedenen Mindestannäherungsdistanzenå der Ionen wurden mittels einer Lösungsmittelextraktionsmethode mitTBP ermittelt. Der beste Wert fürå war 6.5 Å.相似文献
2.
Summary A spectroscopic study of the association in the Nd3+-SCN– system is presented. A characteristic change of the molar absorptivity of the solution with a plateau at 2–4M [SCN–] and an increase at 4–8M [SCN–] reflects the change from outer- to innersphere complexation.
Untersuchungen zur Komplexierung im Nd3+-SCN–-System
Zusammenfassung Es wird eine spektroskopische Studie der Assioziationsverhältnisse im Nd3+-SCN–-System präsentiert. Die charakteristische Änderung in der molaren Absorption der Lösung mit einem Plateau bei 2–4M [SCN–] und ein Anstieg bei 4–8M [SCN–] ist auf einen Wechsel von außensphärischer zu innensphärischer Komplexierung zurückzuführen.相似文献
3.
The overall stability constantsK
1 andK
2 of NdNO
3
2+
and Nd(NO3)
2
+
complexes were determined (K
1=1.77;K
2=1.28) using an extraction method with tri-n-butyl phosphate as the extractant. The ratio 1/2 of the stepwise stability constants is discussed. It was established that the Nd(NO3)
2
+
complex was an outer-sphere ion pair.
Die Assoziation von Nitrat-Ion mit Nd3+
Zusammenfassung Mittels einer Extraktionsmethode wurden die StabilitätskonstantenK 1 undK 2 von NdNO 3 2+ - und Nd(NO3)+-Komplexen bestimmt (K 1=1.77;K 2=1.28; Tri-n-butylphosphat als Extraktionsmittel). Das Verhältnis 1/2 der stufenweisen Stabilitätskonstanten wird diskutiert. Es stellte sich heraus, daß der Nd(NO3)+-Komplex als ein Outer-Shere-Ionenpaar vorliegt.相似文献
4.
Two N‐2‐hydroxy‐1‐phenylethyl and N‐2‐hydroxy‐2‐phenylethyl derivatives of DTPA (3,6,9‐tri(carboxymethyl)‐3,6,9‐triazaundecanedioic acid), DTPA‐H1P = 3,9‐di(carboxymethyl)‐6‐2‐hydroxy‐1‐phenylethyl‐3,6,9‐triazaundecanedioic acid, and DTPA‐H2P = 3,9‐di(carboxymethyl)‐6‐2‐hydroxy‐2‐phenylethyl‐3,6,9‐triazaundecanedioic acid were synthesized. Their protonation constants were determined by Potentiometric titration in 0.10 M Me4NNO3 and by NMR pH titration at 25.0 ± 0.1°C. The formations of lanthanide(III), copper(II), zinc(II) and calcium(II) complexes were investigated quantitatively by potentiometry. The stability constant for Gd(III) complex is larger than those for Ca(II), Zn(II) and Cu(II) complexes with these two ligands. The selectivity constants and modified selectivity constants of the DTPA‐H1P and DTPA‐H2P for Gd(III) over endogenously available metal ions were calculated. Comparing pM values at physiological pH 7.4 assesses effectiveness of these two ligands in binding divalent and trivalent metal ions in biological media. The observed water proton relaxivity values of [Gd(DTPA‐H1P)]? and [Gd(DTPA‐H2P)]? became constant with respect to pH changes over the range of 4‐10. 17O NMR shifts showed that the [Dy(DTPA‐H1P)]? and [Dy(DTPA‐H2P)]? complexes at pH 6.30 had 1.91 and 2.28 inner‐sphere water molecules, respectively. Water proton spin‐lattice relaxation rates of [Gd(DTPA‐H1P)]? and [Gd(DTPA‐H2P)]? complexes were also consistent with the inner‐sphere Gd(III) coordination. 相似文献
5.
N-乙酸基取代四氮杂大环及其镧系配合物的热力学研究 总被引:2,自引:0,他引:2
用pH电位滴定法分别在25±0.1℃,40±0.1℃和80±0.1℃,0.5mol/LKNO3水溶液中测定了H_4L(5,7,12,14-四甲基-1,4,8,11-四氮杂环十四烷-N',n",N"',N""-四乙酸)的逐级质子化常数和焓值。又在40±0.1℃和80±0.1℃条件下测定了H4L与镧系金属离子(La~(3+),Nd~(3+),pr~(3+),Sm~(3+),Eu~(3+),Gd~(3+),Dy~(3+),Yb~(3+))配合物的稳定常数。结果表明:配合物稳定性高。 相似文献
6.
稀土离子(La3+, Gd3+, Yb3+)对线粒体产生活性氧的影响 总被引:2,自引:0,他引:2
研究了稀土离子对分离的线粒体产生活性氧(ROS)的影响. 采用荧光光度法跟踪线粒体内H2O2生成的动力学, 发现三种稀土离子(La3+, Gd3+, Yb3+)均能降低线粒体H2O2的生成; 用黄嘌呤-黄嘌呤氧化酶体系进一步证明稀土对超氧阴离子(·O-2)存在清除作用, 而对H2O2无清除作用; 测定了稀土对线粒体ROS代谢酶(谷胱甘肽过氧化物酶和超氧化物歧化酶)的活性影响. 结果表明, 三种稀土离子对线粒体谷胱甘肽过氧化物酶的活性基本没有影响, 而Gd3+和Yb3+稀土离子能明显抑制线粒体超氧化物歧化酶的活性. 相似文献
7.
主要考察了稀土离子对线粒体氧化损伤(膜脂质过氧化、膜蛋白氧化、线粒体DNA氧化)的作用。结果表明,稀土离子(La3 ,Gd3 ,Yb3 ,Ce3 )浓度大于2×10-5mol.L-1时,对线粒体膜脂质过氧化、膜蛋白氧化均有明显的促进作用;在对Fe2 诱导的线粒体氧化过程中,La3 ,Gd3 和Yb3 能明显地增强Fe2 的氧化作用,而Ce3 对Fe2 的作用表现出明显的拮抗作用,此外Ce3 对Fe2 诱导的线粒体DNA氧化损伤表现出明显的拮抗作用,显示了Ce3 的特殊性。 相似文献
8.
钇(Ⅲ)、铽(Ⅲ)、铒(Ⅲ)对氨基苯甲酸配合物共掺杂二氧化硅的光声光谱研究 总被引:1,自引:0,他引:1
合成了Tb(p-ABA)3·H2O和Ln(p-ABA)3·H2O(p-ABA: 对氨基苯甲酸, Ln: Y或Er)配合物共掺杂的SiO2样品. 荧光光谱测定结果表明, Y(p-ABA)3·H2O的引入增强了样品中Tb3+离子的特征发光, 而Er(p-ABA)3·H2O的引入使Tb3+的发光减弱. 光声光谱结果表明, 与Tb3+配合物单掺的样品相比, Tb3+和Y3+配合物共掺样品的光声强度降低; 而Tb3+和Er3+配合物共掺的样品则情况相反. 实验测定了共掺杂样品的相对量子发光效率和发光寿命, 从无辐射跃迁和辐射跃迁的角度提出共发光效应可能的机制. 结合对室温下陈化干燥样品的分析发现, 只有经适当的热处理过程才能在SiO2凝胶中形成具有多核结构的稀土配合物. 相似文献
9.
A. A. Helal D. M. Imam H. F. Aly 《Journal of Radioanalytical and Nuclear Chemistry》1998,237(1-2):7-11
Humin is separated from a soil sample and characterized by elemental analysis, IR and potentiometric titration. These investigations
indicated that humin displayed similar characteristics as humic acid. The sorption behavior of137Cs,90Sr and153Gd with humin was investigated from aqueous solution. The results indicated that the sorption process follows the order: Gd3+≫Sr2+>Cs+. It was time dependent and increased with pH. The sorption in the presence of humic acid or EDTA showed that both form a
metal-ligand complex and consequently decrease the % uptake. 相似文献
10.
Interaction of the Fungal Metabolite Harzianic Acid with Rare-Earth Cations (La3+, Nd3+, Sm3+, Gd3+)
Gaetano De Tommaso Maria Michela Salvatore Antonietta Siciliano Alessia Staropoli Francesco Vinale Rosario Nicoletti Marina DellaGreca Marco Guida Francesco Salvatore Mauro Iuliano Anna Andolfi 《Molecules (Basel, Switzerland)》2022,27(6)
Rare-earth elements are emerging contaminants of soil and water bodies which destiny in the environment and effects on organisms is modulated by their interactions with natural ligands produced by bacteria, fungi and plants. Within this framework, coordination by harzianic acid (H2L), a Trichoderma secondary metabolite, of a selection of tripositive rare-earth cations Ln3+ (Ln3+ = La3+, Nd3+, Sm3+, and Gd3+) was investigated at 25 °C, and in a CH3OH/0.1 M NaClO4 (50/50 w/w) solvent, using mass spectrometry, circular dichroism, UV–Vis spectrophotometry, and pH measurements. Experimental data can be satisfactorily explained by assuming, for all investigated cations, the formation of a mono-complex (LnL+) and a bis-complex (LnL2−). Differences were found between the formation constants of complexes of different Ln3+ cations, which can be correlated with ionic radius. Since gadolinium is the element that raises the most concern among lanthanide elements, its effects on organisms at different levels of biological organization were explored, in the presence and absence of harzianic acid. Results of ecotoxicological tests suggest that harzianic acid can decrease gadolinium biotoxicity, presumably because of complex formation with Gd3+. 相似文献
11.
Melissa S. Caetano Teodorico C. Ramalho Douglas F. Botrel Elaine F. F. da Cunha Walclee Carvalho de Mello 《International journal of quantum chemistry》2012,112(15):2752-2762
Glyphosate is the active component of one of the top‐selling herbicides, which is also a potent EPSP synthase inhibitor. The herbicide is absorbed by living tissue and translocated via the phloem, to plant roots and rhizomes. When applied directly into the soil it has low activity, due to the high adsorption by soil constituents. Understanding the specific interactions between metals in the soil and glyphosate is the main step in understanding the low activity of the herbicide when applied directly into the ground and not pulverized. We can observe there is a stability order for both tetrahedral and octahedral complexes between glyphosate and metals: Zn>Cu>Co>Fe>Cr>Al>Ca>Mg. © 2012 Wiley Periodicals, Inc. 相似文献
12.
The multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres were successfully synthesized via a template-free solvothermal route without the use of surfactant from commercially available Ln (NO3)3·6H2O (Ln = Gd, Tb and Eu), absolute ethanol, ethanediamine and sublimed sulfur as the starting materials. The phase, structure, particle morphology and photoluminescence (PL) properties of the as-obtained products were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectra. The influence of synthetic time on phase, structure and morphology was systematically investigated and discussed. The possible formation mechanism depending on synthetic time t for the Gd2O2S phase has been presented. These results demonstrate that the Gd2O2S hollow spheres could be obtained under optimal condition, namely solvothermal temperature T = 220 °C and synthetic time t = 16 h. The as-obtained Gd2O2S sample possesses hollow sphere structure, which has a typical size of about 2.5 μm in diameter and about 0.5 μm in shell thickness. PL spectroscopy reveals that the strongest emission peak for the Gd2O2S:xTb3+ and the Gd2O2S:yEu3+ samples is located at 545 nm and 628 nm, corresponding to 5D4→7F5 transitions of Tb3+ ions and 5D0→7F2 transitions of Eu3+ ions, respectively. The quenching concentration of Tb3+ ions and Eu3+ ions is 7%. In the case of Tb3+ and Eu3+ co-doped samples, when the concentration of Tb3+ or Eu3+ ions is 7%, the optimum concentration of Eu3+ or Tb3+ ions is determined to be 1%. Under 254 nm ultraviolet (UV) light excitation, the Gd2O2S:7%Tb3+, the Gd2O2S:7%Tb3+,1%Eu3+ and the Gd2O2S:7%Eu3+ samples give green, yellow and red light emissions, respectively. And the corresponding CIE coordinates vary from (0.3513, 0.5615), (0.4120, 0.4588) to (0.5868, 0.3023), which is also well consistent with their luminous photographs. 相似文献
13.
Two bis(N,N-dialkylamide) derivatives of DTPA [(carboxymethyl)iminobis (ethylenenitrilo) tetraacetic acid], DTPA-BDMA = the bis(N,N-dimethylamide) and DTPA-BDEA = the bis(N,N-diethylamide) were synthesized. Their protonation constants were determined by potentiometric titration in 0.10 M Me4NNO3 and by NMR pH titration at 25.0 ± 0.1 °C. Stability and selectivity constants were measured to evaluate the possibility of using the corresponding gadolinium(III) complexes for magnetic resonance imaging contrast agents. The stability constants of gadolinium(III), copper(II), zinc(II), and calcium(II) complexes with DTPA-BDMA and DTPA-BDEA were investigated quantitatively by potentiometry. The stability constant for gadolinium(III) complexes is larger than those for Ca(II), Zn(II), and Cu(II) complexes. The selectivity constants and modified selectivity constants of the amides for Gd3+ over endogenously available metal ions were calculated. Effectiveness of these two ligands in binding divalent and trivalent metal ions in biological media is assessed by comparing pM values at physiological pH 7.4. Spin-lattice relaxivity values R1 for Gd(III) complexes were also determined. The observed relaxivity values were found to decrease with increasing pH in the acid range below pH 4 and relaxivity values became invariant with respect to pH changes over the range of 4–10. 17O NMR shifts showed that the [Dy(DTPA-BDMA)] and [Dy(DTPA-BDEA)] complexes had one inner-sphere water molecule. Water proton spin-lattice relaxation rates for the [Gd(DTPA-BDMA)] and [Gd(DTPA-BDEA)] complexes were also consistent with one inner-sphere gadolinium(III) coordination position. 相似文献
14.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
15.
Tb^3+和La^3+与牛血清白蛋白作用的光谱研究 总被引:1,自引:1,他引:1
Tb~(3+)和La~(3+)与牛血清白蛋白作用的光谱研究冯志祥,张树功,刘启民,倪嘉缵(中国科学院长春应用化学研究所稀土化学与物理开放实验室长春130022)苗健,油书恒(河南医科大学生化教研室郑州)关键词镧离子,铽离子,牛血清白蛋白,光谱法血清白... 相似文献
16.
The effect on the structural and thermodynamic properties in water/n-heptane interfaces on addition of NaCl, MgCl(2), and ZnCl(2) has been examined through five independent 100-ns molecular dynamics simulations. Results indicate that the interfacial thickness within the framework of the capillary-wave model decreases on addition of electrolytes in the order Na(+) < Mg(2+) < Zn(2+), whereas the interfacial tension increases in the same order. Ionic density profiles and self-diffusion coefficients are strongly influenced by the strength of the first hydration shell, which varies in the order Na(+) < Mg(2+) < Zn(2+). On the other hand, the Cl(-) behavior, that is, diffusion and solvation sphere, is influenced by its counterion. Accordingly, cations are strongly expelled from the interface, which is especially remarkable for the small divalent cations. This fact alters the water geometry near the interface and in a lesser extent n-heptane order and number of hydrogen bonds per water molecule close to the interface. 相似文献
17.
Investigation of Luminescence Properties of Eu3+, Dy3+ and Gd3+ Doped MgAl2Si2O8 Red‐emitting Phosphors
下载免费PDF全文
![点击此处可从《中国化学会会志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rare‐earth‐doped aluminosilicates of alkaline earth MgAl2Si2O8: Eu3+, Dy3+ and MgAl2Si2O8: Eu3+, Gd3+ were synthesized by the solid state reaction method at 1300 oC. The phosphors were characterized by X‐ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). X‐ray powder diffraction studies show that the phosphors were crystallized in the triclinic crystal system. The phosphors show characteristic broad band phosphorescence of Eu3+. This broad band phosphorescence has red emission bands in the range of 580–705 nm corresponding to 5D0 → 7Fj (j:0,2,3,4) transitions of Eu3+. 相似文献
18.
Sulfhydryl MCM-41 (SH-MCM-41) mesoporous materials were prepared via a hydrothermal method, and -SH was successfully imported by a post-grafting method. The structure and surface properties of the materials were characterized using Fourier Transform infrared spectroscopy, X-ray diffraction and Transmission Electron Microscopy analysis. The low concentrations of La3+, Gd3+ and Yb3+ adsorption on the material were investigated. This paper discusses the effects of system factors, such as pH and the solid-liquid ratio, on the performance of the adsorption process. The adsorption thermodynamics and kinetics were also explored. Experimental results indicated that the materials were in good order and had high specific surface area (956 m2/g) with an average pore diameter of 2.1 nm; the mercapto groups were successfully grafted onto a molecular sieve, and the best grafted amount was 1.46 × 10?3 mol/g. The materials showed preferable adsorption of La3+, Gd3+ and Yb3+ with maximum adsorption capacities of 560.56 mg/g, 467.60 mg/g and 540.68 mg/g, respectively. The adsorption process can be described by the Freundlich isotherm model, and the adsorption data fits pseudo-second-order kinetics. After repeating the elution-regeneration cycle four times, the adsorption capacity of rare earth ions was mostly maintained, indicating that the adsorbent can be regenerated well and recycled to save costs. It has potential in practical application. 相似文献
19.
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 O2- to Sm3+ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm3+ f-f transitions of 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2). The O2--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. 相似文献
20.
PENG Wen HU Bin CHEN Yan HU Wei-wei GUO Li YUAN Hong-ming FENG Shou-hua 《高等学校化学研究》2011,27(2):161-165
Pyrochlore titanate oxides, R2Ti2O7(R=Gd3+, Tb3+, Dy3+), were synthesized under mild hydrothermal conditions. The crystal growth of pyrochlore titanate oxides and taking place of chemical reaction in the hydrothermal processing were sensitive to the alkalinity, temperature, reaction time, the nature of the rare earth ion and the composition of initial reaction mixture. The as-prepared samples were characterized by powder X-ray diffraction, scanning electron microscopy, Raman spectrum and variable temperature dc magnetic susceptibility(SQUIDS). The magnetic studies gave 7.29×10–23 A•m2/Gd3+ and –8.28 K, 8.75×10–23 A•m2 /Tb3+ and –19.7 K, and 8.85×10–23 A•m2/Dy3+ and 0.84 K effective moments and Weiss constants for Gd2Ti2O7, Tb2Ti2O7 and Dy2Ti2O7, respectively. 相似文献