高温高压法提取金属富勒烯Ln_m@C_(2n)(Ln=Y,Gd,Tb)

笼内金属富勒烯以其独特的结构性质和潜在的应用价值而引起了人们极大的注意 [1～ 3] ,但因制备技术复杂、产率低以及将其从伴生的空心富勒烯中分离出来比较困难而使其研究受到很大的限制 .笼内金属富勒烯的分离提取始终是金属富勒烯研究的一个重要分支 .通常的方法是将放电得到的烟炱采用甲苯索氏提取的方法粗提 ,然后用高压液相色谱法分离得到纯品 ,笼内金属富勒烯的产率仅为烟炱的 0 .1 % [4～ 6] .我们改进了常规的提取方法 ,建立了一种新的提取方法—高温高压提取法 .具体的做法是采用甲苯索氏提取法从烟炱中提取出空心富勒烯和少量金属富勒烯 ,对剩余物用 1 ,2 ,4-氯苯高温高压法提取 .笼内金属富勒烯的产率增大了 5倍 ( 0 .5 % ) ,这一结果目前尚未见文献报道 .1　实验部分1 .1　金属富勒烯的合成　笼内金属富勒烯 Lnm@C2 n( Ln=Y,Tb,Gd)采用电弧放电法 ,在自制的一套电弧放电器中合成 .将 8mm× 2 0 0 mm的光谱纯级石墨棒钻出 5 mm× 1 5 0 mm的深孔 ,充填经预先处理的各种稀土氧化物和石墨粉的混合物 ,混合物中稀土原子和碳原子物质的量比为 1∶ 5 ...

Studies of Gd-diethylenetriamine pentaacetic acid in boving serum albumin solution by nuclear magnetic resonance spectroscopy

In this paper, the water relaxation enhancement behavior of Gd-diethylenetriamine pentaacetic acid(DTPA) in water and in aqueous solution of bovine serum albumine(BSA) has been studied. The T-1 relaxivity of Gd-DTPA in BSA solution is higher than that in aqueous solution. The results indicate that Gd-DTPA can integrate non-covalently with BSA mainly in forms of (Gd-DTPA) . BSA, (Gd-DTPA)(2) . BSA, for which the apparent equilibrium constant is 0.026 mmol(-1).L,0.0018 mmol(-2).L-2 respectively. This method would be used to study the interactivities between protein and contrast agent.

Studies on insoluble species of Gd (III) in human blood plasma by computer simulation

The insoluble species of Gd (III) in human blood plasma were investigated by computer simulation. The distribution of the Gd (I) species was obtained. It was found that most of the Gd (III) ions were bound to phosphate to form precipitate GdPO4 at the concentration of 1. 000 x 10(-7) mol/L and when the concentration of the Gd (III) increased to 3. 750 x 10(-4) mol/L, in excess of the concentration of phosphate, the Gd (III) ions were bound to carbonate to form another kind of precipitate, Gd-2 (CO3)(3).

Infrared spectra and VUV excitation properties of BaLnB(9)O(16): Re (Ln = La, Gd; Re = Eu, Tb)

The infrared spectra of BaLnB(9)O(16):Re, along with the VUV excitation spectra, have been measured. The spectra were tentatively interpreted in terms of the data on absorptions of the borate groups and band structure. It was observed that there are absorption due to BO3 and BO4 groups, indicating that there are BO3 and BO4 groups in BaLnB(9)O(16). It is found that absorption of the borate groups is located in the range from 120 to 170 mn. This result reveals that there is an energy transfer from host to the rare earth ions. It also observed that the energy of charge transfer band, the host absorption, the total crystal field splitting of d-levels of Tb3+ increase with the decrease in the Ln(3+) radius. (C) 2001 Elsevier Science B.V. All rights reserved.

MAl_2O_4:Eu~(2+)、RE~(3+)长余辉发光性质的研究

研究鳞石英结构碱土铝酸盐MAl2O4 Eu2+、RE3+(M=Mg,Ca,Sr,Ba;RE=Y,La,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu)的荧光及长余辉发光性质.其发光由Eu2+的4f-5d跃迁产生.Re3+作为辅助激活离子,提供合适的陷阱能级.即使用RE3+的特征波长激发,在MAl2O4 Eu2+、RE3+的发光中也观察不到RE3+的发光.基于其荧光,热释光,X-射线,红外光谱等实验结果,分析这一结构对稀土发光的影响,并总结其发光规律

Gd(DTPA-BIN)的热力学性质及与牛血清白蛋白作用的NMR研究

报道了一种新合成的DTPA酰胺类衍生物DTPA－BIN的质子解离过程，其质子化常数总和与稳定性大于DTPA－BMA并采用核磁共振弛豫分析法研究了Gd（DTPA、BIN）在水溶液和牛血清白蛋白溶液中的诱导弛豫增强性质．Gd（DTPA－BIN）配合物在水溶液中弛豫效率为3.28mmol－1·L-1。牛血清白蛋白分子可以与Gd（DTP－BIN）配合物非共价地结合，这种非共价结合体的旋转相关时间明显长于自由配合物，使Gd（DTPA－BIN）在蛋白质溶液中弛豫效率增高．本文结果表明弛豫增强方法可以用来研究顺磁性金属配合物与蛋白质之间的相互作用情况.

NMR studies of Gd(DTPA-BIN) in human serum albumin solution

Stable gadolinium complexes, such as Gd(DTPA) and Gd(DOTA), are usually used as the contrast agents for magnetic resonance imaging(MRI). Reported here are the enhanced relaxation properties of a novel gadolinium complex, diethylene-triaminopentaacetate Lis (isoniazid) [Gd(DTPA-BIN)], in aqueous and in human serum albumin(HSA) solution, which indicates that (1) two Gd(DTPA-BIN) can integrate non-covalently with one HSA with an equilibrium constant of 0. 02 mmol(-2) . L-2 ; (2) the relaxivities are 3. 28 and 4. 92 mmol(-1) . L . s(-1) for the free Gd(DTPA-BIN) and the [Gd(DTPA-BIN)](2), HSA conjugator, respectively; (3) the rotational correlation time of protein conjugator is notably higher than that of the free complex, The above results may imply that Gd(DTPA-BIN) has a higher tissue selectivity than that of its parent Gd(DTPA).

Calculation of nonlinear optical coefficients of orthorhombic Re-2(MoO4)(3) crystals

From the chemical bond viewpoint, the second-order nonlinear optical (NLO) tensor coefficients of some Re-2(MoO4)(3) (ReMO)-type tare earth molybdates, with Re = Pr, Nd, Sm, Eu, Gd, Tb and Dy, have been calculated by using the chemical bond theory of complex crystals and the modified bond charge model. All kinds of constituent chemical bonds are considered in the calculation. The major part of the NLO properties of these ReMO crystals is found from the ReO7 groups. The NLO coefficients of these ReMO crystals decrease with Re from Pr to Dy. (C) 1998 Elsevier Science Ltd. All rights reserved.

The bond ionicity in RBa2Cu3O7 (R=Pr, Sm, Eu, Gd, Dy, Y, Ho, Er, Tm)

RBa2Cu3O7 (R = Pr, Sm, Eu, Gd, Dy, Y, Ho, Er, Tm) has been studied using complex chemical bond theory. The results indicated that with the decreasing of R radius, the ionicities for all considered types of bond decrease. This is in good agreement with the experimental fact that T-c decreases with the decreasing of R radius. PrBa2Cu3O7 with no Ba-site Pr in this calculation is also predicted to be a superconductor. This supports the conclusion obtained by Blackstead et al. The ionicity for each bond obeys the following order: Ba-O > R-O > Cu(2)-O(1) > Cu(2)-O(2,3) > Cu(1)-O(4) similar to Cu(1)-O(1).

(NH4)(3)[PMo12O40]center dot 21H(2)O

The determination of the crystal structure of the title compound, triammonium hexatriacontaoxo(tetraoxophosphato)dodecamolybdate(3-) henicosahydrate, shows that the polyanion has a pseudo-Keggin structure with m (3) over bar m symmetry. The central PO4 group is disordered with P-O distances of 1.55 (3) Angstrom. The Mo-O distances range from 1.617 (14) to 2.414 (14) Angstrom.

CaAl_3BO_7:RE(RE=Ce,Gd,Tb)中稀土离子的光谱特性

采用固相反应法合成了ＣａＡｌ３ＢＯ７ＲＥ（ＲＥ＝Ｃｅ，Ｇｄ，Ｔｂ），研究了Ｃｅ３＋，Ｇｄ３＋和Ｔｂ３＋的光谱特性．发现铈离子周围存在较强的晶场，使基态的４ｆ能级劈裂较大，从而导致铈离子的特征发射峰重叠较大；Ｃｅ３＋的５ｄ能级明显低于Ｇｄ３＋的６Ｉ、６Ｐ能级；Ｃｅ３＋和Ｔｂ３＋之间存在有效的能量传递

The reactivity of lanthanide alkyl compounds with phenylacetylene: Synthesis and structure of [(Bu(t)Cp)(2)LnC CPh](2) (Ln=Nd, Gd)

[(Bu(t)Cp)(2)LnCH(3)](2) (Ln = Nd, Gd) react with PhC=CH to form the dimeric alkynide-bridged complexes [(Bu(t)Cp)(2)LnC=CPh](2) [Ln = Nd (I), Gd (II)]. Both compounds crystallized from toluene in the monoclinic space group C2/c. The two complexes are homologous, composed of asymmetric metal-alkynide bridges with Nd-C, Gd-C (alkynide) bond lengths of 2.602(4), 2.641(5) (I) and 2.532(6), 2.601(7) Angstrom (II), respectively. The average Nd-C (ring) and Gd-C (ring) distances are 2.746(13) and 2.703(19)Angstrom.

Synthesis and crystal structure of (eta(8)-C8H8)Gd(eta(5)-C6H5CH2C5H4)center dot DME

LnCl(3) reacted with C6H5CH2C5H4Na in THF (tetrahydrofuran) in the ratio 1.1 at room temperature for 1 h giving C(6)H(5)CH(2)C(6)H(4)LnCl(2) . nTHF, which reacted with C8H8K2/THF and the crystals obtained were recrystallized in DME to yield the title complex. The crystal structure of (C8H8) Ln (C6H5CH2C5H4). DME was determined revealing that the Gd complex has one conformation. One benzylcyclopentadienyl (eta(5)), one cyclooctatetraenyl (eta(8)) and the two oxygen atoms of DME (dimethoxyethane) are coordinated to Gd with the effective coordination number of 10.

SEMICONDUCTOR TO METAL TRANSITION IN LN(2)MO(3)O(9) COMPOUNDS

Ln(2)Mo(3)O(12) and Ce2Mo3O12.25 are reduced by hydrogen yielding Mo4+ oxides of the formula Ln(2)Mo(3)O(9) (Ln = La, Ce, Pr, Nd, Sm, Gd and Dy). The new compound Ce2Mo3O9 has the same structure as other Ln(2)Mo(3)O(9) compounds. All of the products are single phase materials and crystallize in a tetragonal scheelite type structure with Mo2O6 clusters. The IR spectra of the Ln(2)Mo(3)O(9) oxides show two absorption bands. These compounds are black n-type semiconductors, and exhibit Curie-Weiss Law behavior from 100K to 250K. Temperature dependence of the electrical properties of these compounds were measured for the first time, and a semiconductor-metal transition was found at about 250 degrees C.

A STUDY ON THE LUMINESCENCE PROPERTIES OF EU3+ AND DY3+ IN M(2)RE(8)(SIO4)(6)O-2 (M=MG, CA RE=Y, GD, LA)

In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.