Fabrication of agar-gel microelectrodes and their application in the study of ion transfer across the agar-water 1,2-dichloroethane interface

In this paper, we describe a simple procedure to make agar-gel microelectrodes by filling micropipettes. These microelectrodes were used to study K+ transfer across the agar-water \ 1,2-dichloroethane interface facilitated by dibenzo-18-crown-6 (DB18C6), and the transfer of tetraethylammonium (TEA(+)). The results observed were similar to those obtained at micro-liquid \ liquid interfaces. The effect of various amounts of agar in the aqueous phase was optimized and 3% agar was chosen based on the potential window and solidification time. The different shapes of micro-agar-gel electrodes were prepared in a similar way. The fabricated agar-gel microelectrodes obey the classical micro-disk steady-state current equation, which is different from the behavior of a normal micropipette filled with aqueous solution without silanization. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis and crystal structure of a novel amino-acid-containing polyoxometalate: K-6[Cu (Ala)(2) (H2O)(2)](2)[ CU4 (H2O)(2) (AsW9O34)(2)] center dot 16H(2)O

The novel amino-acid-containing polyoxometalate Ka(6) [Cu(Ala)(2) (H2O)(2)](2) [Cu-4 (H2O)(2) . (AsW9O34)(2)] . 16H(2)O was synthesized from the reaction of K-10[Cu-4(H2O)(2)(AsW9O34)(2)] . 20H(2)O with beta -alanine, Its structure has been determined by single crystal X-ray diffraction. It crystallizes in the triclinic space group P (1) over bar, with a=1. 196 3(2) nm, b=1. 536 5(3) nm, c=1. 591 4(3) nm, alpha =93. 97(3)degrees, beta= 110. 88(3)degrees, gamma =101. 07(3)degrees, V=2. 651 8(9) nm(3) and Z=1. Least-squares refinement of the structure leads to R and R-w factors of 0. 067 3 and 0. 162 8, respectively. An unusual structural feature of the compound is that the polyanion [Cu-4(H2O)(2) (AsW9O34)](10-) is linked with the amino-acid complex of Cu2+ by a mu -oxygen atom.

Four-level decay model of P-6(7/2) excited state of Eu2+ ion in KMgF3

A four-level model of P-6(7/2) excited state of Eu2+ ion in KMgF3: Eu2+ has been proposed. The decay profiles of the P-6(7/2) excited sstate of Eu2+ are two exponential and the physical implication of each term in the fit equation responsible for the model is interpreted. The data obtained spectroscopically are in good agreement with the fit results.

Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

In this work, we report the reverse electron transfer reaction between TCNQ in 1, 2-dichloroethane (DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effects of the concentrations of TBA(+) and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.

Study of energy transfer in KMgF3 : Eu-X (X = Gd, Cr, Ce) by the decay model of P-6(7/2) exited state of Eu2+

Energy transfer processes between Eu2+ and Gd3+, Cr3+, Ce3+ ions in KMgF3, which are difficult to study spectroscopically, have been investigated by using the proposed four-level decay model of the P-6(7/2) excited state of the Eu2+ ion. Gd3+ and Ce3+ transfer its energy to the vibronic transition of the P-6(7/2) --> S-8(7/2) transition of Eu2+, whereas Cr3+ receive energy from Eu2+ via the d-d interaction. The energy transfer from the Eu2+ 4f(6)5d level to the Ce3+ 4f5d state is observed spectroscopically, and the energy transfer mechanism is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis and crystal structure of (1,3-(Bu2C5H3)-Bu-t)(2)Sm(mu-Cl)(2)Li(THF)(2)

Anhydrous SmCl3 reacts with two equal of Li(1-3-(Bu2C5H3)-Bu-t) to give a complex (1,3-(Bu2C5H3)-Bu-t)(2) Sm(mu -Cl)(2)Li(THF)(2) (C34H58Cl2LiO2Sm, M-r = 726.99), monoclinic, space group P2(1)/n, a = 10.615(2), b = 21.037(4), c = 17.166(3) Angstrom, beta = 93.60(3)degrees, V = 3825.7 (13) Angstrom (3), Z = 4, D-c = 1.262 Mg/m(3), mu = 1.699 mm(-1) and F(000) = 1508, final R = 0.0387 and wR = 0.0741 for 5320 observed[I greater than or equal to2 sigma (I)] reflections. The average Sm - C distance is 2.73 Angstrom. Sm - Cl1 and Sm - Cl2 distances are 2.719 (2) and 2. 697 (2) Angstrom, respectively. Two 1, 3-(Bu2C5H3)-Bu-t-ring centroids and two mu (2)-bridging chloride atoms around Sm atom form a distorted tetrahedron.

应用扫描电化学显微镜研究水/1,2-二氯乙烷界面上离子诱导的电子转移反应

应用扫描电化学显微镜和微电极技术研究了水 / 1,2 二氯乙烷界面上的反向电子转移反应 .分别以K4 Fe(CN) 6和 7,7,8,8 四氰代二甲基苯醌 (TCNQ)作为水相和有机相的电活性物质 ,通过选择合理的共同离子 (TPAs+与TBA+)来控制界面电位差 ,实现了这一在热力学上通常不可能实现的反向电子转移反应 .利用扫描电化学显微镜给出的正负反馈信息 ,研究了界面电位差驱动的液 /液界面上的电子转移反应 ,并进一步得到了在不同的共同离子浓度比时 ,此异相界面反应速率常数kf 为 1 3× 10 -31 8× 10 -2 cm/s(共同离子为TBA+)和 2 5× 10 -32 8× 10 -2 cm/s(共同离子为TPAs+) .验证了此反应速率常数kf 是由界面电位差所决定的 .在此实验条件下 ,此反应速率常数kf 与界面电位差的关系遵守Butler Volmer公式 .

BaY_2F_8∶Ce,Eu中Ce~(3+)→Eu~(2+)的能量传递和Ce~(3+)→Eu~(3+)的电子转移

采用高温固相反应法制备了 Ba Y2 F8∶ Ce3 + ,Ba Y2 F8∶ Eu2 + 和 Ba Y2 F8∶ Ce,Eu,测定了它们的激发、发射和漫反射光谱 .首次发现并研究了在 Ba Y2 F8共掺 Ce F3 和 Eu F3 体系中存在 Ce3 + → Eu2 + 的能量传递和Ce3 +→ Eu3 +的电子转移两种过程及其竞争 .根据光谱数据 ,讨论了 Ce4 +的可能取代格位

KMgF_3∶Eu和KMgF_3∶Eu-Ce单晶体中Eu~(2+)与Ce~(3+)的格位取代和能量传递

在 77K测定了两个晶体的高分辨发射光谱 ,讨论了单掺杂 Eu2 + 和双掺杂 Eu2 + 及 Ce3+ 的 KMg F3中的格位取代问题 .在 KMg F3∶ Eu-Ce中观察到了 Eu2 + 的 6P5/ 2 能级到 Ce3+ 的 4 f 5 d能级间的间接能量传递 ,讨论了能量传递机理

KMgF_3∶Eu,X(X=Ce,Cr,Gd,Cu)体系中Eu~(2+)振动光谱和共掺离子的格位取代

测定了一系列单掺杂 Eu2 +和双掺杂 Eu,X( X=Ce,Cr,Gd,Cu)的 KMg F3晶体在 30 0 K和 77K的高分辨发射光谱以及伴随的振动光谱 ,据此研究了 Eu2 + 在这些体系中的振动跃迁特征 ,并指认了每一振动峰所对应的正则振动模式 .首次发现了在共掺杂体系中 Eu2 +振动频率与其它掺杂离子格位取代间的相关性

三环己基锡-2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸酯的结构研究

合成了 3个三环己基锡 -2 -( 1 ,2 -亚乙二硫 )亚甲基 -3-羰基 -5 -芳基 -4 -戊烯酸酯化合物 .用 IR,1 H NMR,1 3 C NMR和 1 1 9Sn NMR光谱及 X射线衍射对所合成的化合物进行了表征 .结果表明标题化合物为四配位、具有畸变四面体结构的锡酯类化合物

应用玻璃微米/纳米管和循环伏安法研究邻菲咯啉加速质子在水/1,2-二氯乙烷界面的转移过程

利用循环伏安法研究了玻璃微米 /纳米管支持的水 / 1 ,2 -二氯乙烷 ( DCE)界面上邻菲咯啉加速质子的转移过程 .将装有水溶液的微米 /纳米管插入到 DCE溶液中 ,可以形成微米 /纳米级 -液 /液界面 ,在选定的实验条件下 ,其作用类似于微米 /纳米电极 .用微米管考察了此加速转移过程的半波电位与 p H值 ( 1 .1～7.5 )的关系 ,利用 Matsuda等提出的理论公式计算了邻菲咯啉与质子在有机相和水相中的络合常数比 .并用纳米管计算得到邻菲咯啉加速质子在水 / DCE界面转移过程中的标准速率常数 ( k0 )和转移系数 (α)分别为( 0 .1 83± 0 .0 5 4 ) cm/ s和 0 .70± 0 .0

Ce_(1-x)Ca_xO_(2-x)的溶胶-凝胶法的合成及其性质

用溶胶 -凝胶法合成了 Ce1-x Cax O2 -x(x=0～ 0 .3 5 )系列固体电解质 ,系统地研究了其晶体结构随Ca O含量的变化关系 .XRD测试表明 ,该体系于 1 60℃即形成萤石结构纯相 .高温 XRD表明 ,从室温至80 0℃ ,Ce1-x Cax O2 -x(x=0～ 0 .3 5 )未出现结构相变 .此法合成温度远低于传统的高温固相合成法和水热合成法的温度 .合成物的颗粒小 ,粒度均匀 .在 1 3 0 0℃即可烧结成高致密度样品 .XPS测试表明 ,掺杂 Ca O后吸附氧浓度明显增大 ,氧空位增多 ,电导率和氧离子迁移数增大 ,改善了 Ce O2 基固体电解质的性能 .

Synthesis and characterization of a new layered zinc phosphate: (C3H4N2)(3)Zn-4(HPO4)(PO4)(2) with imidazole coordinating to Zn atoms

A new two-dimensional hybrid zinc phosphate with electro-neutral open-framework has been hydrothermally synthesized by using imidazole as a structure-directing agent, whose structure is characterized with 3-, 4-, 5, and 12-ring layers and coordination bonds between imidazole groups and zinc atoms, resulting in primary building units of ZnO2N2 and ZnO3N.

The effect of KSCN on the partition of proteins in polyethylene glycol/(NH4)(2)SO4 aqueous two-phase system

The effect of potassium thiocyanate on the partitioning of lysozyme and BSA in polyethylene glycol 2000/ammonium sulfate aqueous two-phase system has been investigated. As a result of the addition of potassium thiocyanate to the PEG/ammonium sulfate system, the PEG/mixed salts aqueous two-phase system was formed. It was found that the potassium thiocyanate could alter the pH difference between the two phases, and, thus, influence the partition coefficients of the differently charged proteins. The relationship between partition coefficient of the proteins and pH difference between two phases has been discussed. It was proposed that the pH difference between two phases could be employed as the measurement of electrostatic driving force for the partitioning of charged proteins in polyethylene glycol 2000/ammonium sulfate aqueous two-phase system.