氢键诱导的聚吡咯/苯磺酸功能化多壁碳纳米管的制备及其电化学行为

采用原位芳基重氮化反应对碳纳米管进行苯磺酸功能化, 进而制备了聚吡咯/苯磺酸化碳纳米管复合材料(PPy/f-MWCNTs), 通过透射电镜(TEM)及扫描电镜(SEM)测试发现, 氢键诱导使聚吡咯成功地包覆在碳纳米管表面. 循环伏安和恒流充放电测试结果表明, 复合材料具有良好的电化学电容性能, 当聚吡咯与苯磺酸化碳纳米管质量比为1:1时, 复合材料在1.0 A·g-1的电流密度下的比容量达266 F·g-1, 而且聚吡咯利用率比未功能化聚吡咯/碳纳米管(PPy/p-MWCNTs)和纯聚吡咯(PPy)提高了1倍以上.     

膨胀石墨表面化学镀镍及性能

采用化学镀法对膨胀石墨表面镀镍. 对包覆后的样品进行了SEM、EDS、XRD、IR和磁性能表征. 结果表面,膨胀石墨表面被镍层均匀包覆,其质量分数镍占94.12%、磷占5.88%,镀覆后产品在近红外波段反射率明显增大,磁性能明显增强,饱和磁化强度σs=26.3 A·m2/kg、剩磁σr=8.1 A·m2/kg、σr/σs=0.31,分析结果表明其属于软磁性材料.     

空心微米镍球的表面改性及微波吸附性能研究

采用特殊的化学镀方法对已制备的空心微米镍球进行表面组装, 成功地在该镍球表面包覆了一层蜂窝状包覆钴层. 通过FESEM, TEM, XRD衍射表征了该包覆镍球, 观察到均匀包覆钴层的网眼构造和密集孔隙结构. 用BET气体吸附法、同轴线法对该镍球比表面积和微波性能进行了研究. 研究表明, 蜂窝状包覆钴层提高了粒子的比表面积, 同时表面镀钴提高了镍球的复介电常数值, 从而能增加粒子对电磁波的电介质损耗, 提高粒子在微波频率范围内对电磁波的反射吸收.     

磁场下化学镀Co-Ni-B-Ce合金层微观形貌和耐磨性

磁场下化学镀Co-Ni-B-Ce合金层微观形貌和耐磨性;化学镀钴-镍-硼合金;铈;表面形貌;磁场     

多孔羰基铁/SiO2/聚吡咯核壳结构复合材料的制备及电磁特性

首先对羰基铁进行点腐蚀得到多孔羰基铁,然后采用St?ber法和原位聚合法将SiO_2和导电高分子聚吡咯包覆在多孔羰基铁表面,制备多孔羰基铁/SiO_2/聚吡咯电磁复合吸波材料。采用XRD、SEM、TEM、FT-IR对样品结构、微观形貌进行了表征,在网络分析仪中采用同轴法测试样品电磁参数,并根据传输线理论研究了2~18 GHz微波频段内吡咯含量及涂层厚度对样品吸波性能的影响。实验结果表明:制备的多孔羰基铁/SiO_2/聚吡咯复合电磁吸波材料具有核壳结构;随着吡咯加入量的增加,吸波材料吸收峰逐渐向低频方向移动;当涂层厚度为3.5 mm、吡咯加入量为6%(w/w)时,在9.44~17.56 GHz范围内反射率均低于-10 d B,频带宽度为8.12 GHz,损耗反射率达到-23 d B。良好的吸波性能归因于复合物有效的阻抗匹配特性及多重界面极化效应,多孔羰基铁/SiO_2/聚吡咯是一种轻质、宽频、强吸收的吸波材料。     

NiCF/ABS复合材料的制备及电磁屏蔽效能研究

探讨了碳纤维(CF)表面镍金属的化学镀工艺,制备了镀镍碳纤维(NiCF),采用密炼工艺制备了ABS基体复合材料,研究了CF和NiCF含量对复合材料的导电性能及电磁屏蔽效能的影响。结果表明:采用化学镀的方法在碳纤维表面镀覆了金属镍,所形成的镀层均匀致密;镀覆时间为5min时,镀镍后的碳纤维电阻率降低两个数量级;复合材料电阻率随CF、NiCF含量的增加而逐渐减小;复合材料电磁屏蔽效能随CF、NiCF含量的增加而逐渐增加,当NiCF含量为25%(wt)(约13.3vol%)时,电磁屏蔽效能最高可达51dB。     

聚吡咯/纳米SiO_2复合材料的制备及氧化性能

采用化学氧化法制备聚吡咯/纳米Si O2(PPy/n Si O2)复合材料,通过扫描电子显微镜和红外光谱对其进行表征,并将其应用到对苯二酚的氧化反应中.结果表明,PPy/n Si O2复合材料中,PPy较均匀地负载在纳米Si O2表面.在弱酸性介质中,PPy/n Si O2对对苯二酚具有很好的氧化性能.反应2 h内,对苯二酚的氧化过程符合表观一级反应动力学.结合紫外-可见光谱法分析表明,聚吡咯通过与对苯二酚之间的氢键相互作用形成聚吡咯活性中间体,将对苯二酚氧化为对苯醌,聚吡咯具有氧化剂和催化剂的双重功能.     

碳纳米管表面的无钯活化化学镀镍研究

本文提出碳纳米管表面无钯活化的化学镀镍方法.碳纳米管经硝酸氧化和碱中和后表面生成羧基,利用羧基吸附镍离子,之后吸附的镍离子被化学还原为镍的纳米微粒并成为化学镀镍的催化活性中心.红外吸收光谱和电子显微镜观察等证实了上述活化过程的机理.实验表明,新的活化方法对碳纳米管表面化学镀是切实可行的,文中同时对化学沉积层的不同形貌进行讨论.     

聚吡咯/亚铁氰化钾/碳纳米管修饰电极检测亚硝酸根

采用循环伏安法在滴涂碳纳米管的电极表面制备了聚吡咯/K4Fe(CN)6复合膜,研究了该电极的电化学性质及对NO2-的电催化还原。结果表明,固定于聚吡咯膜中的K4Fe(CN)6作为电子递质与碳纳米管和聚吡咯对NO2-电还原具有协同催化作用,安培法检测NO2-的线性范围为1.5×10-6～1.8×10-3mol/L,检出限为3.0×10-7mol/L,该法已用模拟水样中NO-的测定。     

非共价修饰碳纳米管/二氧化钛复合材料的合成及性能

采用溶胶-凝胶法在聚乙烯吡咯烷酮(PVP)非共价修饰的碳纳米管表面均匀沉积二氧化钛粒子制得纳米复合材料。用TEM、XRD、FTIR、N2吸脱附等对复合材料进行了表征。结果表明:纳米二氧化钛纳米粒子均匀沉积在被修饰碳纳米管表面,且二氧化钛为纯锐钛矿晶体结构,没有金红石和板钛矿相。非共价修饰碳纳米管/二氧化钛复合材料具有良好的介孔结构,其孔径分布主要集中在6～10 nm,且比表面积与纯的二氧化钛相比明显增大,在紫外光照射下降解亚甲基蓝,相比纯的二氧化钛和碳纳米管/二氧化钛,具有较高的催化活性。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.