白钨矿型钨酸盐和钼酸盐纳米晶/微晶制备研究进展

综述近年来自钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术领域的研究进展,重点介绍熔盐法、有机配合物前驱法、模板法、微乳液法、水热法、溶剂热法和微乳液.溶剂热法的原理和技术特点,比较各种方法的异同点,并提出白钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术的发展趋势.     

铁酸盐的制备、表征及其催化性能的研究

采用空气氧化湿法制备了含Zn、 Ni、 Co的尖晶石型铁酸盐。运用XRD、IR、UV-DRS和TPR等方法对所制备的样品进行了表征。研究了铁酸盐的化学组成、结构和氧化还原性质。考察了铁酸盐对二氧化碳选择性氧化乙苯制苯乙烯的催化性能,并讨论了催化剂的结构、组成对反应活性的影响以及二氧化碳的作用。     

溶胶-凝胶法制备铁酸盐超微粒子催化剂

采用溶胶－凝胶法制备了含Zn,Ni,Co的铁酸盐超微粒子催化剂，运用DTA－TG、IR、XRD以及BET比表面测试等手段对所制备的样品进行了表征。同时，考察了铁酸盐对二氧化碳选择性氧化乙苯制苯乙烯的催化性能。结果表明：制备的铁酸盐均为尖晶石型晶体，粒子的比表面积为31．9－36．3m^2/g，晶粒大小约为30－35nm，在由二氧化碳选择性氧化乙苯制苯乙烯的反应中表现出较好的催化活性。     

CoxFe3—xO4纳米晶的合成与性能研究

Co_xFe_(3-x)O_4晶体属尖晶石型结构,具有良好的磁光效应及化学稳定性。在尖晶石型铁氧体中,金属离子存在着A-A、B-B和A-B晶位间超交换作用,其中以A-B间的超交换作用最强。超交换作用引起不同次晶格的磁矩反向排列,而铁氧体的亚铁磁性则来源于晶格中A、B位上未抵消的反向磁矩。尖晶石型单一铁氧体MFe_2O_4晶格中离子分布通常为Fe_xM_(1-x)[M_xFe_(2-x)]O_4。在三价铁盐和二价钴盐混合水溶液中滴加碱液可制备CoFe_2O纳米晶。本文用改进的化学共沉淀法,以不同摩尔浓度的Co(Ⅱ)和Fe(Ⅱ)合成Co_xFe_(3-x)O_4纳米晶系列样品,考察了样品组成与其磁性的关系。     

尖晶石型铁酸盐催化剂的担体效应考察

用共沉淀法和浸渍法制备了ZnFe_2O_4、ZnCrFeO_4以及它们在γ-Al_2O_3,TiO_2,SiO_2小球上的担载催化剂.用TPR.XRD.ESR,MBS,脉冲反应等技术对这些催化剂进行了考察.结果表明,载体的引入在不同程度上改变了催化剂的氧化还原性能.在不同的载体上形成尖晶石结构的趋势不同.铁酸盐尖晶石相无论是非载的还是担载的对于多次交替的氧化还原处理不敏感.然而氧化铁相则较不稳定,而且在不同载体上稳定性相差较大.加Cr组份有助于担体上形成正尖晶石相.在某些较难形成铁酸盐尖晶石相的担载催化剂中,其相的组成较为复杂.脉冲反应的结果表明,担载的单一正尖晶石铁酸盐以及γ-Al_2O_3上的氧化铁对丁烯氧化脱氢均有一定的活性,对于既含较多量正尖晶石铁酸盐又含一定量氧化铁的催化剂,其较好的催化性能暗示在这两相之间可能存在某种协同效应.     

α-Fe_2O_3-MgO复合氧化物的制备和气敏性能

用化学共沉淀法制备了 α-Fe2 O3-Mg O复合金属氧化物纳米晶微粉 .并对其相组成 ,电导和气敏性能作了研究 .结果表明 ,镁铁摩尔比 n(Mg2 )∶ n(Fe3 ) =1∶ 2、5 0 0℃下热处理 4h可得纯相尖晶石型复合金属氧化物 Mg Fe2 O4;电导测量显示 ,该材料呈 n型半导体导电行为 . 60 0℃下热处理 4h所得纳米晶微粉制作的元件在 2 2 7℃工作温度下对 C2 H5OH有较高灵敏度和良好的选择性 .     

α-FeO3-MgO复合氧化物的制备和气敏性能

用化学共沉淀法制备了α-Fe2O3-MgO复合金属氧化物纳米晶微粉。并对其相组成,电导和气敏性能作了研究。结果表明,镁铁摩尔比n(Mg^2 ):n(Fe^3 )=1:2,500℃下热处理4h可得纯相尖晶石型复合金属氧化物MgFe2O4;电导测量显示,该材料呈n型半导体导电行为,600℃下热处理4h所得纳米晶微粉制作的元素在227℃工作温度下对C2H5OH有较高灵敏度和良好的选择性。     

铁酸锌纳米晶的机械化学合成

以αFe₂O₃和ZnO粉体为原料,在高能球磨的作用下,室温(约25℃)合成了铁酸锌(ZnFe₂O₄)纳米晶.用XRD、TEM、M?sbauer谱及IR光谱等方法对纳米晶进行了表征.结果表明:所得纳米晶具有非正型分布的尖晶石结构,为超顺磁性;纳米晶内存在着较多的缺陷.     

CoFe2—xRExO4（RE=Tb,Dy）纳米晶薄膜的化学合成及磁性

以溶胶－凝胶法制备了稀土铽或镝掺杂的钴尖晶石铁氧体纳米晶薄膜。考察了Ｔｂ或Ｄｙ的掺杂量及晶化条件对晶相的影响。结果表明，稀土离子的掺杂量ｘ超过０．３时，样品很难题形成尖晶石单相。     

尖晶石型铁酸盐的制备和表征研究

本文采用空气氧化湿法制备尖晶石铁酸盐，得到最佳生成条件为：Ｒ－２ＯＨ＾－／（Ｍ＾２＋＋Ｆ２＋）≥１．０；Ｍ＾２＋／Ｆｅ＾２＋＝０．５摩尔比；氧化温度３４３－３５８Ｋ；氧化时间１０－２５小时。通过ＸＲＤ、ＴＰＲ和ＴＰＤ等方法对其进行表征，讨论了尖晶石型铁酸盐的氧化－还原活及其化学组成和结构的变化。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.