阴离子掺杂改性纳米TiO_2的光催化性能

利用钛酸丁酯水解浸渍方法制备了多种阴离子掺杂改性TiO2纳米复合粉体材料,并作了XRD、BET等表征,研究了它们对气相光催化降解正己烷反应的活性,并和阳离子K+ 掺杂TiO2、未掺杂TiO2及商品TiO2 Degussa P-25作了比较。结果表明,在实验的掺杂浓度下,多数阴离子的掺杂虽对TiO2的光催化活性略有降低,但仍要优于P-25,活性最差的是钾离子掺杂TiO2,H3PO4和NH4H2PO4的掺杂则对TiO2的光催化活性有明显的促进作用。     

NH4H2PO4掺杂改性纳米TiO2的光催化性能

利用钛酸丁酯水解浸渍方法制备了几种不同浓度NH4H2PO4掺杂改性的TiO2纳米复合粉体材料并作了XRD、BET等表征。以正己烷的气相光催化氧化降解为探针反应研究了NH4H2PO4掺杂TiO2催化剂的光催化活性。并和未掺杂TiO2及商品TiO2 Degussa P-25作了比较．结果表明。掺杂NH4H2PO4能够显著地细化TiO2的晶粒度。增大TiO2的比表面积。同时，适量掺杂NH4H2PO4对TiO2的光催化活性也有较大的促进作用。     

H3PO4改性纳米TiO2气相光催化降解正己烷

利用钛酸丁酯水解浸渍方法制备了几种不同浓度H3PO4改性的TiO2纳米复合粉体材料并作了XRD、BET等表征，以正己烷的气相光催化氧化降解为探针反应研究了H3PO4改性TiO2催化剂的光催化活性，并和未改性TiO2及商品TiO2 Degussa P-25作了比较．结果表明，H3PO4改性能够显著地细化TiO2的晶粒度，增大TiO2的比表面积，同时，适量掺杂H3PO4对TiO2的光催化活性也有较大的促进作用．H3PO4作为掺杂物有优于NH4H2PO4之处．     

控制胶体合成法制备掺铁TiO_2粉末及光催化降解甲基橙

分别采用控制胶体合成法和溶胶-凝胶法制备了2种不同掺铁方式的TiO2粉末,并用XRD、TEM、BET、UV-Vis、FS等技术对样品进行了表征。在紫外光照射下,以甲基橙溶液的光催化降解反应为探针,研究了掺Fe离子浓度、包覆的次数、不同掺杂方式对样品光催化活性的影响。结果表明,以均匀掺铁TiO2(铁含量大于0.02mol%)干凝胶粉末为载体,采用控制胶体合成法制备了具有P-N结型结构的非均匀掺铁TiO2粉末,其光催化活性较均匀掺杂TiO2粉末明显提高,并且随着包覆次数(≤3次)的增加而增强,以0.04mol%掺铁TiO2粉末包覆3次后制备的样品具有最佳光催化活性,其表观速率常数是未掺杂的TiO2粉末的5.32倍,是具有相同Fe含量的均匀掺杂TiO2粉末的4.58倍。     

液相沉积法制备光催化活性掺铁TiO2薄膜

 通过在氟钛酸铵－氟铁酸混合溶液中加入硼酸溶液，应用液相沉积法制备了具有高光催化活性的掺铁TiO2薄膜．用ICP－AES测定了掺铁TiO2薄膜中Fe3＋的浓度，用XRD，AFM，UV－Vis和阶梯仪等对TiO2薄膜的沉积条件、结构、膜厚和性能进行了表征，并以亚甲蓝降解反应评价了掺铁TiO2薄膜的光催化活性．结果表明，在硼酸／六氟钛酸铵摩尔比为2～4时，掺铁TiO2薄膜中含有锐钛矿相TiO2．当掺Fe3＋浓度为0．05％，热处理温度为300℃时，掺铁TiO2薄膜具有最高的光催化活性，其光催化活性是未经热处理时的3．9倍，是经300℃热处理但未掺铁TiO2薄膜的1．4倍．     

MCM-41分子筛担载纳米TiO2复合材料光催化降解罗丹明B

采用溶胶-凝胶法将TiO2担载在介孔MCM-41分子筛上, 制备了不同TiO2含量的系列TiO2/MCM-41复合材料, 利用X射线衍射、N2吸附、紫外-可见光谱和透射电镜等方法对其进行表征. TiO2的晶型为锐钛矿相, 复合材料的比表面积和孔体积随其中TiO2担载量(复合材料中TiO2与MCM-41的质量比)的增加而减小, TiO2的平均粒径随其担载量的增加而增大. 以罗丹明B的光催化降解为探针反应, 评价了TiO2/MCM-41复合材料的光催化降解活性. 结果表明, 在紫外光照射下, 罗丹明B在该复合材料上的光催化降解反应遵循一级反应动力学, 复合材料对罗丹明B的光催化降解活性明显高于商用TiO2 (P-25), 复合材料的光催化降解活性由复合材料的吸附能力和所含TiO2的光催化活性共同决定.     

MCM-41分子筛担载纳米TiO2复合材料光催化降解罗丹明B

采用溶胶.凝胶法将TiO2担载在介孔MCM-41分子筛上,制备了不同TiO2含量的系列TiO2/MCM-41复合材料,利用X射线衍射、N2吸附、紫外-可见光谱和透射电镜等方法对其进行表征.TiO2的晶型为锐钛矿相,复合材料的比表面积和孔体积随其中TiO2担载量(复合材料中TiO2与MCM-41的质量比)的增加而减小,TiO2的平均粒径随其担载量的增加而增大.以罗丹明B的光催化降解为探针反应,评价了TiO2/MCM-41复合材料的光催化降解活性.结果表明,在紫外光照射下,罗丹明B在该复合材料上的光催化降解反应遵循一级反应动力学,复合材料对罗丹明B的光催化降解活性明显高于商用TiO2(P-25),复合材料的光催化降解活性由复合材料的吸附能力和所含TiO2的光催化活性共同决定.     

可见光响应的铁掺杂TiO_2中空微球的制备及其光催化性能

以聚苯乙烯微球作为模板,水溶性过氧化钛配合物作为前驱体一步合成了掺铁TiO2中空微球,并利用XRD,SEM,TEM,XPS,UV-Vis等测试手段对样品进行了表征。结果表明,一步法制备的掺铁TiO2中空微球以锐钛矿相存在且具有良好的中空结构,掺杂少量铁到体系中,改变了其电子结构,使其吸收波长拓展到可见光区。光催化降解亚甲基蓝溶液的结果表明,掺杂0.75%铁的TiO2中空微球表现出更好的光催化性能。对Fe3+影响光催化活性的机理进行了讨论。     

低温苯甲醇醇解法制备高活性锐钛矿型纳米晶TiO2光催化剂

 以TiCl4 为钛源,采用低温苯甲醇醇解法制备了不同粒径及晶相组成的大表面TiO2纳米晶,利用X射线衍射、热重-差热分析、透射电子显微镜、拉曼光谱、紫外-可见漫反射光谱和N2物理吸附等方法考察了焙烧温度和焙烧时间对其晶相组成、晶粒尺寸、比表面积及孔体积等微结构性质的影响,并以苯酚的光催化降解为模型反应评价了样品的光催化活性. 结果表明,未经任何热处理的TiO2样品即为锐钛矿晶相,控制焙烧温度及焙烧时间可进一步调控样品的粒径、比表面积、晶相结构及表面氧缺位浓度. 经400 ℃焙烧3 h制备的纳米晶TiO2具有最佳的光催化活性,其活性比商用Degussa P-25 TiO2更高.     

掺铂二氧化钛纤维光催化降解氯仿的研究

 TiO2纤维作为一种微米级光催化剂应用于废水处理时，不但克服了TiO2纳米颗粒不易分离回收的困难，而且对其进行贵金属掺杂，可使其光催化活性大大提高．用光还原沉积法制备了掺铂的二氧化钛纤维催化剂（Pt／TiO2（F）），并将其作为光催化剂用于光催化降解氯仿反应，考察了掺铂量、氧及pH值等条件对降解氯仿反应的影响，并与掺铂的二氧化钛颗催化剂粒（Pt／TiO2（G））的光催化活性进行了比较．结果表明，当掺铂量w（Pt）＝0．5％，催化剂用量为0．5g／L，预先溶氧至饱和状态，c0（CHCl3）＝1mmol／L，pH＝5，用300W中压汞灯光照120min时，Pt／TiO2（F）上氯仿的降解率可达98．44％，而Pt／TiO2（G）上氯仿的降解率仅为72．03％．     

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.