硅钼杂多阴离子薄膜修饰电极的研究和应用——线性扫描伏安法测定水中可溶性硅酸盐

本文研究了以玻碳电极为基体的1:12硅钼杂多酸根(SiMo_(12)O_(40)~(4-)简称12-MSA)修饰电极的制备及其电化学行为,将12-MSA电极应用于线性扫描伏安法测定天然水中可溶性硅酸盐,结果满意.硅浓度在8.0×10~(-7)～1.7×10~(-3)mol/L,相对标准偏差(n=7)为1.85％,加标回收率为98.2％～103.6％,SiMo_(12)电极具有优良的选择性和稳定性。     

卡尔曼滤波分光光度法同时测定钢样中的硅、磷、砷

研究了在聚乙烯醇存在下,硅、磷、砷钼杂多酸与罗丹明6G形成离子缔合物的反应,建立了能同时测定硅、磷、砷的卡尔曼滤波分光光度法。用于钢样中微量硅、磷、砷的同时测定,操作简便快速,相对误差小于8％。     

Dynamic stereochemistry of hypervalent silicon, germanium and tin compounds containing amidomethyl C, O-chelating ligands

The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamomethyl, and related bidentate ligands are surveyed. For the series of works “Dynamic stereochemistry of hypervalent compounds of silicon, germanium, and tin,” the author was awarded the Academia Europea Prize for young scientists from CIS in 1996. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1912–1934. November, 1997.     

制备高比表面积碳化硅的几种影响因素

采用溶胶凝胶法，以蔗糖和正硅酸乙酯(TEOS)为原料，草酸为TEOS水解的催化剂，制备均相碳化硅前驱体，在氩气氛和高温条件下(1 350～1 600 ℃)将碳化硅先驱体进行碳热还原，制备出高比表面积的SiC。考察了水/TEOS物质的量的比、碳/硅物质的量的比及镍盐等因素对碳化硅比表面积的影响。结果表明，当n_water/n_TEOS=7.5，n_C/n_Si=4时，适宜的镍催化剂(n_Ni/n_TEOS=0.005)，凝胶形成的时间最短，镍盐的加入可使碳热还原温度降低200 ℃。     

Synthesis and characterization of new oligosilane derivatives of iron and molybdenum

By use of salt elimination, the transition metal substituted oligosilanes (η⁵-C₅Me₄Et)Fe(CO)₂SiMe₂SiMe₂Cl 1, (η⁵-C₅Me₄Et)Mo(CO)₃SiMe₂SiMe₂Br 2, (η⁵-C₅Me₄Et)Fe(CO)₂(SiMe₂)₆(CO)₂Fe(η⁵-C₅Me₄Et) 3 and (η⁵-C₅Me₄Et)Fe(CO)₂(SiMe₂)₆Br 4 were prepared and characterized. Compound 1 is well crystallized from pentane and its structure has been determined by X-ray diffraction analysis.     

Synthesis of New Lithium Ionic Conductor Thio-LISICON—Lithium Silicon Sulfides System

The new lithium ionic conductors, thio-LISICON (LIthium SuperIonic CONductor), were found in the ternary Li₂S-SiS₂-Al₂S₃ and Li₂S-SiS₂-P₂S₅ systems. Their structures of new materials, Li_4+xSi_1−xAl_xS₄ and Li_4−xSi_1−xP_xS₄ were determined by X-ray Rietveld analysis, and the electric and electrochemical properties were studied by electronic conductivity, ac conductivity and cyclic voltammogram measurements. The structure of the host material, Li₄SiS₄ is related to the γ-Li₃PO₄-type structure, and when the Li⁺ interstitials or Li⁺ vacancies were created by the partial substitutions of Al³⁺ or P⁵⁺ for Si⁴⁺, large increases in conductivity occur. The solid solution member x=0.6 in Li_4−xSi_1−xP_xS₄ showed high conductivity of 6.4×10^-4 S cm⁻¹ at 27°C with negligible electronic conductivity. The new solid solution, Li_4−xSi_1−xP_xS₄, also has high electrochemical stability up to ∼5 V vs Li at room temperature. All-solid-state lithium cells were investigated using the Li_3.4Si_0.4P_0.6S₄ electrolyte, LiCoO₂ cathode and In anode.     

The interactions of (=O→Si)-(benzoyloxymethyl)trifluoro-and -(benzoyloxymethyl) methyldifluorosilanes with a solvent

The IR spectra of solutions of (=OSi)-(benzoyloxymethyl)trifluorosilane (1),-(benzoyloxymethyl)methyldifluorosilane (2), and butyl benzoate (3) are examined in the region of thev(C=O) stretching vibrations in 24 solvents. The ability of compounds1—3 to undergo specific intermolecular interactions is evaluated from the dependence ofv(C=O) on the Kamlet-Taft (^*,, ) parameters, which was obtained for the carbonyl groups involved in the intramolecular coordinate (=OSi) bond and for free carbonyl groups. The corresponding values of the coefficients in the Kamlet-Taft equations are indicative of a weak ability of pentacoordinate silicon compounds1 and2 to undergo acid-base interactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 689–692, April, 1995.     

p—Si上电沉积Ni—W—P薄膜的结构与热稳定性

研究了ｐ－Ｓｉ上恒电流沉积Ｎｉ－Ｗ－Ｐ合金薄膜组成与结构的关系，讨论了镀层的组成、结构随沉积时间的变化．测定了非晶合金的晶体结构随热处理温度的改变以及ＤＴＡ曲线，结果表明，非晶Ｎｉ－Ｗ－Ｐ合金在晶化过程中形成两个纳米超微晶相，非晶Ｎｉ－Ｗ－Ｐ薄膜的热稳定性远高于通常使用的非晶Ｎｉ－Ｐ薄膜．     

Structural evolution of calcium-exchanged (NH4)2SiF6-dealuminated Y zeolite after various chemical treatments

The structural evolution of Y zeolite (Si/Al 2.17) weakly dealuminated by hexafluorosilicate (Si/Al 3.13), denoted Y_D, and exchanged with calcium (CaY_D), has been studied after acid–base treatments at 80 °C close to the cation exchange conditions. The stability of the samples was followed by X-ray diffraction and solid-state NMR of ²⁹Si and ²⁷Al; Y_D zeolite was completely destroyed by treatment with acid pH 2.5 and suffered serious degradation on treatment with alkali at pH 11.8. The introduction of calcium improved the stability of the zeolite in acid and base. In acid CaY_D was not destroyed until pH 1. At pH 2, silicon and aluminium were extracted and an amorphous phase was formed. Base treatment at pH 13 did not affect the calcium-exchanged zeolite.     

Towards EPC-syntheses of the structural class of cochleamycins and macquarimicins. Part 2: EPC-synthesis of the hydrindene subunit of the macquarimicins

The EPC-synthesis of the cis-hydrindene subunit of the macquarimicins, antibiotics with antitumour and anti-inflammatory activity, has been achieved. Desymmetrization of cis-1,4-cyclopent-2-enediol was succeeded by Diels-Alder reaction and functional group transformations to a tricyclic ketone. Regio- and stereoselective methylation via Claisen condensation and hydrogenation was followed by nucleophilic, intramolecular addition, reduction and acidic fragmentation. Further functional group transformations led to the target molecule.