Synthesis, Character and Crystal Structure of the Complex {Er（DMSO）7} PW12O40

The synthesis, X-ray crystal structure, thermal properties and electrochemistry of the new complex formulated as {Er(DMSO)7}PW12O40 are reported. The single-crystal X-ray analysis reveals that the crystal crystallizes in the monoclinic system, space group P21/c with a = 11.767(2), b = 14.909(3), c = 34.905(7) , β = 98.97(3)°, Mr = 3591.33, V = 6049(2) 3, Dc = 3.944 g/cm3, Z = 4, GOOF = 1.098, F(000) = 6340, R = 0.0490 and wR = 0.1202. Crystal structure analysis indicates that the Er(Ⅲ) is seven-coordinate with a distorted pentagonal bipyramid and combines to the anion [PW12O40]3- via static electric force.     

铌酸盐 Ba5YTi3 Nb7 O30的结构与介电性能

在BaO-TiO2-Mb2O5体系中通过掺Y3－合成了铌酸盐Ba5YTi3Nb7O30 ,采用粉晶X射线衍射（XRD）对其结构进行了分析,并测试了其烧结体的介电特性,结果表明,在室温下Ba4YT3 Nb7O30属于填满型四方钨青铜结构,晶胞参数,a=1.24332(2)nm,c=0.39453(1)nm,α=β=γ＝90度,Ba5TYi3Nb7O30在100度从铁电相转变为顺电相。     

新铌酸盐Sr5LnTi3Nb7O30的结构与介电性能

在SrO-Ln2O3-TiO2-Nb2O5(Ln=La, Y)体系中,通过固相反应法，合成了填满型钨青铜结构新铌酸盐Sr5LaTi3Nb7O30与Sr5YTi3Nb7O30.分别采用X射线衍射分析、扫描电镜进行了结构分析,并进行了介电性能测试.结果表明, Sr5LaTi3Nb7O30室温时为四方钨青铜结构顺电相,晶胞参数a=1.233 60(4) nm, c=0.388 01(2) nm;频率为1 MHz时,其陶瓷的室温相对介电常数为466,介电损耗约为5×10－3.Sr5YTi3Nb7O30为弛豫性铁电体, 10 kHz时居里温度为260 ℃;室温时为四方钨青铜结构铁电相,晶胞参数a=1.228 80(4) nm, c=0.387 05(2) nm; 1 MHz时,陶瓷体的室温相对介电常数为290.     

新铌酸盐Sr5NdTi3Nb7O30的合成与介电特性

一些铁电铌酸盐具有优良的电光性能和非线性光学性能,因此该类化合物的人工合成、结构与性能的研究受到了重视,其中钨青铜结构的系列晶体(例如SBN、KNSBN、SCNN)在材料的制备和器件的设计方面都取得了很大进展,它们在实时全息存储、集成     

提高Nb2O5中Ta2O5光谱分析的灵敏度

由于Ｎｂ２Ｏ５与Ｔａ２Ｏ５物理、化学性质相似，主体Ｎｂ２Ｏ５对Ｔａ分析线强度干扰很大。因此，Ｎｂ２Ｏ５中光谱测定Ｔａ２Ｏ５的灵敏度很差，为了提高Ｔａ分析线强度，通常的光谱条件选择是无效的。实验表明在旋流气室中，采用高含量Ａｒ的（Ａｒ、Ｏ２）控制气氛电弧激发，提高了Ｎｂ２Ｏ５中Ｔａ２Ｏ５的光谱分析灵敏度。然而，由于Ｎｂ２Ｏ５在高温下易于被碳还原，虽然用Ｓｔａｌｌｗｏｏｄ喷咀可以改善蒸发，减慢样品还原     

溶胶-凝胶法制备高取向K(Ta,Nb)O3薄膜

K(Ta,Nb)O_3具有良好的电光特性、非线性光学特性和热释电特性.K(Ta,Nb)O_3薄膜在光电子集成电路中有着良好的应用前景.国外主要是进行K(Ta,Nb)O_3单晶和陶瓷的研究工作,近年来也有制备K(Ta,Nb)O_3薄膜的报导.我们采用溶胶-凝胶法制备KTa_(0.65)Nb_(0.35)O_3薄膜.制备过程如下:把Ta(OC_2H_5)_5,Nb(OC_2H_5)_5和K(OC_2H_5)溶于无水C_2H_5OH 中配成0.2     

共沉淀法合成Pb3Nb2O8纳米粉

在PbO-Nb₂O₅-KOH-H₂O体系中,于90℃下得到纳米级Pb₃Nb₂O₈陶瓷粉.原料来源及配比、溶液碱度及合成温度对产物物相的形成有较大影响.在Pb₃Nb₂O₈的合成中,必须以可溶性铌酸盐和醋酸铅作为反应原料,同时以KOH调节体系中铌酸盐的聚集状态.当n(Pb)/n(Nb)接近1/1,KOH浓度在1～3mol/L时,得到Pb₃Nb₂O₈纯相,当KOH浓度大于3mol/L时容易生成反应活性较低的PbO,产生杂相.     

An open-framework cobalt molybdate possessing {Mo2O7} building block: hydrothermal synthesis and structural characterization of [CoMo2O7(4,4′-bipy)1.5]

The hydrothermal reaction of Co(COO)₂?·?4H₂O, MoO₃, H₃PO₄ and 4,4′-bipyridine yields bipyridine-ligated cobalt dimolybdate [CoMo₂O₇(4,4′-bipy)_1.5] (1) (4,4′-bipy?=?4,4′-bipyridine) in the triclinic system with space group of P 1 and cell parameters of a?=?7.1951(8)?Å, b?=?11.1708(17)?Å, c?=?11.4514(11)?Å, α?=?98.545(7)°, β?=?90.315(2)°, γ?=?105.777(5)°, V?=?874.88(19)?ų, and Z?=?2. Its structure consists of Co/Mo/O bimetal oxide layers with {Mo₂O₇} building blocks, linked by the coordination of 4,4′-bipy ligand with Co and Mo atoms, into a 3D porous hybrid framework.     

Activation of α-keto acid-dependent dioxygenases: application of an {FeNO}7/{FeO2}8 methodology for characterizing the initial steps of O2 activation

The α-keto acid-dependent dioxygenases are a major subgroup within the O(2)-activating mononuclear nonheme iron enzymes. For these enzymes, the resting ferrous, the substrate plus cofactor-bound ferrous, and the Fe(IV)═O states of the reaction have been well studied. The initial O(2)-binding and activation steps are experimentally inaccessible and thus are not well understood. In this study, NO is used as an O(2) analogue to probe the effects of α-keto acid binding in 4-hydroxyphenylpyruvate dioxygenase (HPPD). A combination of EPR, UV-vis absorption, magnetic circular dichroism (MCD), and variable-temperature, variable-field (VTVH) MCD spectroscopies in conjunction with computational models is used to explore the HPPD-NO and HPPD-HPP-NO complexes. New spectroscopic features are present in the α-keto acid bound {FeNO}(7) site that reflect the strong donor interaction of the α-keto acid with the Fe. This promotes the transfer of charge from the Fe to NO. The calculations are extended to the O(2) reaction coordinate where the strong donation associated with the bound α-keto acid promotes formation of a new, S = 1 bridged Fe(IV)-peroxy species. These studies provide insight into the effects of a strong donor ligand on O(2) binding and activation by Fe(II) in the α-keto acid-dependent dioxygenases and are likely relevant to other subgroups of the O(2) activating nonheme ferrous enzymes.     

K2B4O7-Na2B4O7-Li2B4O7-H2O四元体系273 K介稳相平衡

采用等温蒸发平衡法研究了四元体系K2B4O7-Na2B4O7-Li2B4O7-H2O在273 K时的介稳相平衡及平衡液相的密度. 研究发现该四元体系为简单共饱和型, 无复盐及固溶体形成, 根据溶解度数据绘制了相图, 相图中有一个共饱点E, 三条单变度曲线E3E, E2E, E1E; 三个平衡固相分别为K2B4O7·4H2O、Na2B4O7·10H2O 和LiBO2·8H2O. 并简要讨论了实验结果.     

K2B4O7-Na2B4O7-Li2B4O7-H2O 四元体系15℃介稳相平衡研究

采用等温蒸发平衡法研究了四元体系K2B4O7-Na2B4O7-Li2B4O7-H2O15℃时的介稳相平衡及平衡液相的物化性质(密度,粘度,电导率,折光率,pH)。根据实验数据绘制了相图,相图中有一个共饱点E,三条单变度曲线E3F,E2F,E1F;三个平衡固相分别为：K2B4O7•4H2O,Na2B4O7•10H2O和Li2B2O4•16H2O;硼酸钾具有最大溶解度,硼酸钠具有最小溶解度。同时,根据试验数据绘制了组成－物化性质关系图,从图可见溶液的密度,粘度和折光率均随着溶液浓度的增大而逐渐增大,在共饱和点F处达到最大值,而溶液的pH值和电导率却随着溶液浓度的增大呈总体下降的趋势。     

Synthesis,characterization,properties and crystal structure of heterometallic 1D coordination polymers {[CuLZn·CuLZn(H_2O)]·H_2O}_n

Heterometallic complexes with novel structure have attracted much attention both from the material sci- ence and model study of metal enzymes[1―6]. Over the last two decades, a number of heterometallic binuclear complexes have been synthesized and investin- gated[7―9], many heterometallic polynuclear complexes have also been reported, but investigation of coordina- tion polymers is still very limited. One of the success- ful strategies in obtaining the desired heterometallic complexes is the…     

ICP-AES法测定镍铜合金中的Fe,Mn,Cr,Nb

建立了ICP–AES法测定镍铜合金中Fe,Mn,Cr,Nb元素的分析方法。进行了基体元素Ni,Cu及共存元素对分析元素的光谱干扰研究,分别选择259.940,257.610,283.563,316.340 nm作为分析谱线,确定内标用量为2.00 mL。测定结果的相对标准偏差为0.48%～4.71%(n=8),加标回收率为95.0%～103.4%。该法满足分析要求。     

Molecular electrostatic potentials and electron deformation densities from Xα calculations. The case of O2, O2− and O22−

A molecular-orbital study, performed using both multiple scattering Xα and ab initio SCF models, is reported for the protonation process of O₂, O₂⁻ and O₂²⁻. The main features of both molecular electrostatic potential and electron deformation density contour maps are compared and discussed.     

Bis[tetraruthenium(IV)]-containing polyoxometalates: [{Ru(IV)4O6(H2O)9}2Sb2W20O68(OH)2]4- and [{Ru(IV)4O6(H2O)9}2{Fe(H2O)2}2{β-TeW9O33}2H]-

The reaction of [Sb(2)W(22)O(74)(OH)(2)](12-) and [Fe(4)(H(2)O)(10)(β-TeW(9)O(33))(2)](4-) with (NH(4))(2)[RuCl(6)] in aqueous solution resulted in the novel ruthenium(IV)-containing polyanions [{Ru(IV)(4)O(6)(H(2)O)(9)}(2)Sb(2)W(20)O(68)(OH)(2)](4-) and [{Ru(IV)(4)O(6)(H(2)O)(9)}(2){Fe(H(2)O)(2)}(2){β-TeW(9)O(33)}(2)H](-), exhibiting two cationic, adamantane-like, tetraruthenium(IV) units {Ru(4)O(6)(H(2)O)(9)}(4+) bound to the respective polyanion in an external, highly accessible fashion.     

{[(n-Bu)2Sn(O2CCH=CHAr)]2O}2的合成、表征和{[(n-Bu)2Sn(O2CCH=CHPh)]2O}2的晶体结构

利用(n-Bu)2SnO与ArCH=CHCO2H反应,合成5个二聚二丁基锡芳基丙烯酸酯氧化物{[(n-Bu)2Sn(O2CCH=CHAr)]2O}2.通过元素分析、红外光谱和核磁共振氢谱对其结构进行了表征.用X射线单晶衍射测定了{[(n-Bu)2Sn-(O2CCH=CHPh)]2O}2 (1)的晶体结构,结果表明,化合物1是以Sn2O2四面体为中心的,中心对称的二聚体结构,内环锡为五配位的畸变三角双锥构型,外环锡为六配位的畸变加帽体三角双锥结构.该化合物属三斜晶系,空间群P1-, a=1.0172(11) nm, b=1.3804(16) nm, c=1.4703(17) nm, α=106.750(18)°, β=105.61(2))°, γ=100.295(18)°, Z=1, V=1.829(4) nm-3, Dc=1.413 g/m3, μ=1.400 mm-1, F(000)=792, R=0.0559, wR=0.1250.     

Nb2O5·nH2O as a heterogeneous catalyst with water-tolerant Lewis acid sites

Niobic acid, Nb(2)O(5)·nH(2)O, has been studied as a heterogeneous Lewis acid catalyst. NbO(4) tetrahedra, Lewis acid sites, on Nb(2)O(5)·nH(2)O surface immediately form NbO(4)-H(2)O adducts in the presence of water. However, a part of the adducts can still function as effective Lewis acid sites, catalyzing the allylation of benzaldehyde with tetraallyl tin and the conversion of glucose into 5-(hydroxymethyl)furfural in water.