钛酸纳米管的化学修饰及发光性能的稳定化

钛酸纳米管表面富有羟基, 利用十六醇与Ti-OH发生脱水反应对钛酸纳米管进行化学修饰. 通过透射电子显微镜、红外光谱和荧光光谱等方法研究了表面修饰对钛酸纳米管的结构及光学性质的影响. 与未修饰的钛酸纳米管相比, 不溶于有机溶剂的钛酸纳米管修饰后溶于氯仿、甲苯中, 为进一步用LB膜技术组装钛酸纳米管提供了条件, 并且钛酸纳米管表面修饰的有机层有效抑制了纳米管表面对水的吸附, 解决了钛酸纳米管在空气中久置或有水气氛下特殊的可见区吸收和荧光发光现象受到影响的问题, 使钛酸纳米管的发光性质稳定, 为钛酸纳米管的广泛应用奠定了基础.     

聚3-甲基噻吩及聚3-己基噻吩修饰钛酸盐纳米管的光电化学性能研究

采用水热法制备了钛酸盐纳米管, 并将钛酸盐纳米管制备成纳米结构电极进行光电化学研究. 钛酸盐纳米管产生阳极光电流, 具有n-型半导体特性. 结果表明, 聚3-甲基噻吩[poly(3-methylthiophene), PMeT]、聚3-己基噻吩[poly(3-hexylthiophene), P3HT]修饰钛酸盐纳米管后产生的光电流均较纯钛酸盐纳米管的光电流高, 且使产生光电流的波长向长波区移动. 钛酸盐纳米管/PMeT、钛酸盐纳米管/P3HT的光电转换效率分别达11.40%, 0.91%(未校正光子损失). 钛酸盐纳米管/PMeT的光电转换效率较钛酸盐纳米管/P3HT的光电转换效率高10.5%. 钛酸盐纳米管/PMeT、钛酸盐纳米管/P3HT中存在p-n异质结, 在一定条件下p-n异质结的存在有利于光生电子/空穴的分离.     

阳极氧化法制备多段氧化钛纳米管阵列

光滑管壁结构与竹子结构氧化钛纳米管在一些应用方面分别表现出各自的优势,比如光滑管壁结构氧化钛纳米管更适合电子的传输,竹子结构氧化钛纳米管增加了纳米管的比表面积.集合了两种结构特点的氧化钛纳米管将会在一些应用方面更加优秀.我们提供了一种通过阳极氧化简单制备多段氧化钛纳米管阵列的方法,这种多段氧化钛纳米管是由光滑管壁结构与竹子结构交替组成的.直流电压与交流电压交替使用分别得到氧化钛纳米管的光滑管壁段和竹子结构段.直流电压与交流电压各自的持续时间可以对段长完全控制.并且我们指出了得到这种多段氧化钛纳米管阵列应该注意的问题.首先,为了避免纳米管段与段之间的分裂,电压切换时氢离子的分布不应该被扰乱;其次,为了避免纳米管各段之间因为直径出现差别而断裂,直流电压的大小应该等于交流电压的大电压.这种多段的纳米管阵列期望在太阳能电池,药物传输等方面得到广泛应用.     

铂掺杂氮化硼纳米管及CO在其表面的吸附行为的理论研究

采用基于密度泛函理论的PBEPBE方法对铂(Pt)掺杂的氮化硼(BN)纳米管进行了理论研究. 计算结果表明, Pt原子突出BN纳米管表面, Pt的d轨道暴露到外面, 使它更容易和外来分子发生相互作用, 提高了纳米管的反应活性. Pt取代掺杂缩小了纳米管的能隙, 从而提高BN纳米管的导电性. 一氧化碳(CO)在Pt掺杂BN纳米管上的吸附行为表明, 2个CO能化学吸附到纳米管表面, 更多的CO分子吸附是物理吸附.     

聚合物纳米管研究进展

全面综述了聚合物纳米管的制备方法及研究现状。根据聚合物纳米管的制备机理和实施方法的不同 ,可分为三类 :(1)多孔模板法 ;(2 )线模板法 ;(3)自组装法。详细总结了各种方法制备聚合物纳米管的研究成果 ,展望了制备聚合物纳米管新技术的开发前景和聚合物纳米管的应用前景     

H2与C,BN和GaN纳米管的相互作用势能

基于C,B,N和Ga与H原子间的L-J势函数,系统计算了H2处于(n,n)(n=8,10,12)单壁C,BN和GaN纳米管内部及外部不同处的势能.根据势能变化曲线,分析了3种纳米管氢物理吸附能力的差异,给出了H2在3种纳米管外部的势能表达式.研究结果表明:3种纳米管内部的氢吸附力均分别高于管外;随着纳米管直径的增加,各纳米管管内的氢吸附力均略有下降,而管外变化不明显;GaN,BN和C纳米管依次具有更好的储氢能力.     

CeO_2/ZnO复合纳米管的制备及其光催化性能的研究

用纳米CeO2掺入ZnO纳米管制备了CeO2/ZnO复合纳米管,考察了复合纳米管的光学及其光催化性能,并运用X射线衍射、透射电镜、比表面积测定和紫外-可见漫反射光谱等技术对样品进行了表征.结果表明,与ZnO纳米管相比,CeO2/ZnO复合纳米管的比表面积虽有所降低,但光催化活性有所提高,随着复合纳米CeO2量的增加,催化剂的光催化活性相应降低,太阳光下CeO2/ZnO复合纳米管对甲基橙溶液也有较高的催化活性.     

高比表面积TiO_2纳米管的制备与表征

采用一种简单的化学合成方法制备TiO2 纳米管 ,并采用TEM、XRD等分析手段对TiO2 纳米管进行了表征 .考察了不同温度对TiO2 纳米管比表面积及孔体积的影响 .结果表明 ,采用该方法制得的TiO2 纳米管 ,比用模板法制备的TiO2 纳米管的管径小、管形均匀 .此纳米管的比表面积大于 2 0 0m2 /g ,孔体积最大可达 0 .784cm3 /g .     

钛酸盐纳米管的制备及光电性能研究

采用水热法制备了钛酸盐纳米管, 并用TEM、XRD、XPS对其进行了表征. 纳米管管径在5~30 nm之间, 管长约为0.1~1 μm, 具有不同于锐钛矿型的钛酸盐结构, 分子组成可能是Na4－xHxTi2O5. 将钛酸盐纳米管制备成纳米管结构电极, 并进行了光电化学研究. 钛酸盐纳米管产生阳极光电流, 具有n型半导体特性.     

负载银纳米管钛酸催化剂的制备

采用光催化还原法制备了载银纳米管钛酸,通过TEM可以看到纳米管钛酸表面附着有银颗粒,XPS和XRD等结果显示银颗粒是以单质银的形式存在.对亚甲基蓝光催化降解实验结果表明:载银纳米管钛酸催化剂的催化活性比未载银纳米管钛酸催化剂的活性高.     

Bromination of 4‐Dichloromethyl‐4‐methylcyclohexa‐2,5‐dien‐1‐ones

Bromination of 4‐dichloromethyl‐4‐methylcyclohexa‐2,5‐dien‐1‐one and 4‐dichloromethyl‐3,4‐dimethylcyclohexa‐2,5‐dien‐1‐one has been studied. The reaction conditions required for the formation of mono‐, di‐, and tribrominated products have been optimized.     

A Simple,Convenient One‐Pot Synthesis of Dithio‐Carbamide Derivatives of Heterocyclic 1,3‐Dicarbonyl Systems

A various new dithi‐ocarbamides were synthesized from heterocyclic six‐membered 1,3‐dicarbonyl systems, such as 4‐hydroxy‐2,5‐pyranopyridines, 4‐hydroxy‐2‐pyridones, 4‐Hydroxy‐2‐quinolones, 4‐hydroxy‐coumarins, and 4‐hydroxy‐1‐methyl‐2‐quinolones. The dicarbonyl compounds in the presence of anhydrous potassium carbonate in dimethyformamide react with tetraalkylthiuram disulfides to yield 3‐dialkylaminothiocarbonylthio derivatives through a simple, convenient one‐pot reaction. The structures were confirmed by using IR, NMR, and elemental analysis.     

Novel Method for the Synthesis of 6,12‐Dihydro‐2‐Methylindolo[2,3‐ b]Carbazol‐6‐Ones

A novel method for the synthesis of 6,12‐dihydro‐2‐methylindolo[2,3‐b]carbazol‐6‐ones was developed from 1‐oxo‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐one through methyl 6‐methyl‐2‐(1‐oxo‐2,3,4,9‐tetrahydro‐1H‐carbazol‐2‐yl)oxoacetate in good yields. This method provides an alternative path for the synthesis of this product using 2‐hydroxy methylene‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐one.     

Synthesis,Reactions, Characterization and Biological Evaluation of 2,3′‐Bipyridine Derivatives (III)

1‐Pyridin‐3‐yl‐3‐(2‐thienyl of 2‐furyl)prop‐2‐en‐1‐ones 1a , 1b reacted with 2‐cyanoethanethioamide 2 to afford the corresponding 4‐(thiophen‐2‐yl or furan‐2‐yl)‐6‐sulfanyl‐2,3′‐bipyridine‐5‐carbonitriles 3a , 3b . The synthetic potentiality of compounds 3a , 3b were investigated in the present study via their reactions with several active halogen containing compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 5 , 5a , 5b . Our aim here is the synthesis of 4‐(2‐thienyl or 2‐furyl)‐6‐pyridin‐3‐ylthieno[2,3‐b]pyridin‐3‐amines 6a , 6b , 6c , 6d , 6e , 6g , 6h , 6i , 6j , 6k , 6l , 6m , 6n ,via 6‐(alkyl‐thio)‐4‐(2‐thienyl or 2‐furyl)‐2,3′‐bipyridine‐5‐carbonitriles 5a , 5b , 5c , 5d , 5e , 5i , 5j , 5k , 5l , 5m . The structures of all newly synthesized heterocyclic compounds were elucidated by considering the data of IR, ¹H‐NMR, mass spectra, as well as that of elemental analyses. Anti‐cancer, anti‐Alzheimer, and anti‐COX‐2 activities were investigated for all the newly synthesized heterocyclic compounds.     

The Study on Synthesis of Some New 1,2,3‐Triazolylurea and Carbonyl Amide Derivatives

The study on syntheses of some N‐substituted‐N′‐[5‐methyl‐1‐(4‐chlorophenyl)‐1,2,3‐triazol‐4‐yl]‐urea 6a‐e and N‐substituted‐[5‐methyl‐1‐(4‐chlorophenyl)‐1,2,3‐triazol‐4‐yl]carbonyl amide 6f‐l derivatives were reported in this paper. The yielded products 6a‐l were confirmed by elemental analyses, NMR, MS and IR spectra.     

Synthesis of 3‐Aryl‐2‐methoxyinden‐1‐one (Z)‐Phenylhydrazones via Hydrobromic Acid‐Mediated Cyclization of 2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehyde Phenylhydrazones

2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes 2 , obtained by successive treatment of 1‐(1‐aryl‐2‐methoxyethenyl)‐2‐bromobenzenes 1 with BuLi and 1‐formylpiperidine, were transformed to the corresponding phenylhydrazones 3 on treatment with PhNHNH₂. When these hydrazones were allowed to react with conc. HBr, cyclization, followed by dehydrogenation with air occurred, furnished 3‐aryl‐2‐methoxyinden‐1‐one (Z)‐phenylhydrazones 4 .     

Melamine Trisulfunic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′‐(Arylmethylene)‐bis‐(1H‐pyrazol‐5‐ols)

Melamine trisulfunic acid is employed as a recyclable catalyst for the condensation reaction of aromatic aldehydes with 3‐methyl‐l‐phenyl‐2‐pyrazolin‐5‐one. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4′‐(arylmethylene)‐bis‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ols) in 80‐96% yields.     

Synthesis of 4‐Arylisocoumarins (=4‐Aryl‐1H‐2‐benzopyran‐1‐ones) through Acidic Hydrolysis of (Z)‐2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes,Followed by Oxidation

4‐Arylisocoumarins (=4‐aryl‐1H‐2‐benzopyran‐1‐ones) 6 were prepared from 2‐(1‐aryl‐2‐methoxyethenyl)‐1‐bromobenzenes 1 . Successive treatment of these bromo styrenes with BuLi and 1‐formylpiperidine gave a mixture of (E)‐ and (Z)‐2‐(1‐aryl‐2‐methoxyethenyl)benzaldehydes 2 . Hydrolysis of (Z)‐isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H‐2‐benzopyran‐1‐ol derivatives 4 (and 5 ), afforded the desired products.     

Synthesis of 4,6‐Dimethyldibenzothiophene and 1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene via Tilak Annulation

1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohexanone with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. A mixture of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene and 4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. 2‐Bromo‐3‐methylcyclohexanone was synthesized by conjugate addition of Me₃Al to 2‐bromocyclohex‐2‐en‐1‐one with CuBr as catalyst and 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one by bromination? elimination of 3‐methylcyclohex‐2‐en‐1‐one. 1,2,3,4,4a,9b‐Hexahydro‐4,6‐dimethyldibenzothiophene was prepared by reduction of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene with Zn and CF₃COOH.     

Synthesis and cytotoxic activity of silacycloalkyl‐substituted heterocyclic aldehydes and their thiosemicarbazones

A series of 5‐[1‐methylsilacyclo‐pentyl/‐hexyl]‐2‐furfural, 5‐[1‐methylsilacyclo‐pentyl/‐hexyl]‐2‐thiophene carbaldehyde and 1,1‐bis(5‐formyl‐2‐furyl)silacyclo‐pentane/‐hexane and their thiosemicarbazones has been synthesized and subjected to antitumour assay. The effects of the substituents and the heterocycle were examined to establish structure–activity relationships. Thiosemicarbazones of 5‐(1‐methylsilacyclohexyl)furfural and 5‐(1‐methylsilacyclopentyl)furfural were very active (1.0–4.0 µg ml^?1) in vitro against human fibrosarcoma HT‐1080 and mouse hepatoma MG‐22A cells. At the same time, they were less toxic for normal fibroblasts 3T3. All compounds synthesized exhibited low or moderate toxicity (LD₅₀ 152–1904 mg kg^?1). Copyright © 2005 John Wiley & Sons, Ltd.