ZnO/PPy异质纳米复合材料的制备、表征及其气敏特性

室温下, 采用原位聚合法, 以吡咯(PY)为单体, 氯化铁(FeCl₃·6H₂O)为氧化剂, 在塑料基片上聚合生长了聚吡咯(PPy)纳米微球. 然后在聚吡咯基片上生长ZnO种子, 将表面种有ZnO种子的PPy元件置于六次甲基四胺与硝酸锌的混合溶液中, 90 ℃水浴中, 在PPy微球上生长了ZnO纳米棒, 合成了PPy/ZnO异质纳米复合材料. 分别通过X射线衍射仪(XRD)和场发射扫描电镜(FESEM)对PPy/ZnO异质纳米复合材料的结构和形貌进行了表征. 制备了塑料基的PPy/ZnO异质纳米复合材料气体传感器, 在室温下, 对10×10^-6-150×10^-6 (体积分数)浓度范围的氨气进行了气敏测试, PPy/ZnO气敏元件对氨气响应的灵敏度基本呈线性关系, 且对甲醇、丙酮、甲苯等有机气体表现出很好的选择性. 最后, 对PPy/ZnO异质纳米复合材料的形成机理进行了简要分析.     

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.     

用离子吸附法制备银/聚吡咯同轴纳米电缆

以多元醇还原反应法制备出直径为40~50 nm的纳米银线, 采用醋酸铜水溶液对银纳米线表面进行处理, 通过离子吸附在纳米银线表面吸附铜离子. 以吸附在银纳米线表面上的铜离子作为活性单元, 氧化吡咯单体聚合, 制得Ag/PPy同轴纳米电缆. 采用TEM, FTIR和XPS等表征手段对产物进行表征和检测, 并通过表面增强拉曼光谱进一步证实产物中聚吡咯层紧密地吸附在银线表面. 结果表明, 利用醋酸铜作为氧化剂, 通过离子吸附法制备的Ag/PPy同轴纳米电缆, 可以在较大范围内有效地控制聚吡咯层厚度, 避免银纳米线被刻蚀.     

聚吡咯/STAB-NaMMT/GC电极对苯二酚的电化学行为研究

利用十八烷基三甲基溴化氨（STAB）和聚吡咯（PPy）钠基蒙脱土制备了PPy/STAB钠基蒙脱土/GC电极（PPy/STAB-NaMMT/GC）.用循环伏安法和方波溶出伏安法（SWSV）研究了对苯二酚在该电极上的电化学行为.实验表明,在pH 6.0 PBS电解液中,对苯二酚在该电极的电极反应受扩散控制,转移的电子数与质...     

无纺布基聚吡咯柔性电极的储锂性能

高性能的柔性锂离子电池对可穿戴电子设备的发展具有重要意义。采用化学氧化法在聚对苯二甲酸乙二醇酯(PET)无纺布基材上原位聚合聚吡咯(PPy),并通过控制反应条件得到不同形貌的聚吡咯电极材料。当反应体系中剪切力较小时,得到纳米线状聚吡咯(PPy-NW/PET),反之,为纳米颗粒形貌的聚吡咯(PPy-NP/PET)。PPy纳米线的平均直径为460 nm,在包覆PET纤维的同时相互交叠,形成了三维网状导电通道。该PPy/PET可以直接作为无粘结剂的柔性电极材料。电化学测试结果表明,PPy-NW/PET电极材料的性能更优异,其首次放电和充电的比容量分别为124和98 mA[DK1]·h/g,且具有良好的柔性和稳定性。本文对柔性、轻质电极材料的制备及其在储能领域的应用提供了很好的思路。     

蒽醌/聚吡咯复合膜修饰电极的电化学行为和电催化活性

在水溶液中制备了掺杂蒽醌磺酸盐(AQS)的聚吡咯(PPy)/玻碳复合膜修饰电极,采用循环伏安法和旋转圆盘电极技术研究了该修饰电极在不同pH值溶液中的电化学行为以及在pH=5.5的磷酸盐缓冲溶液中对氧还原反应的电催化性能和动力学.结果表明,与裸玻碳电极相比,PPy膜的存在不仅降低了AQS的反应电位和峰电位差,而且增大了其氧化还原反应的峰电流,H2AQ/HAQ-氧化还原对的电离常数为9.5.AQS/PPy膜修饰电极上氧的还原主要是两电子还原为H2O2的不可逆过程,H2AQ对氧还原反应起主要催化作用,还原过程符合异相氧化还原催化机理.该修饰电极具有良好的电化学重现性.     

纳米石墨薄片/聚吡咯复合材料的制备及导电性能

膨胀石墨经过超声处理制备了纳米石墨薄片。以其为导电填料，对甲苯磺酸为掺杂剂，FeCl₃·6H₂O为氧化剂，引发吡咯单体发生原位聚合，制备出纳米石墨薄片/聚吡咯(NanoGs/PPy)复合材料。利用红外光谱(FTIR)、扫描电镜(SEM)和透射电镜(TEM)表征了材料的组成和结构。结果表明，石墨薄片被聚吡咯完全包覆；并且以纳米级尺寸分散在聚吡咯基体中。热失重(TG)分析和电导率测试结果表明，复合材料的耐热性能和导电性能较纯聚吡咯有所提高。     

不同形貌聚吡咯的制备及其电化学性能研究

以吡咯为单体,用化学氧化法和电化学沉积法分别制备聚吡咯(PPy)纳米粒子和微球。实验表明,PPy-ED微球的比电容要优于PPy-CS纳米粒子,并且PPy微球表现出理想的赝电容行为,可以进行快速可逆的法拉第反应,其原因在于PPy微球分子链规整,具有较大的共轭程度,从而表现出优异的电化学储能性。     

聚吡咯/海藻酸钠纳米球的制备及其应用于高性能超级电容器

用海藻酸钠作为结构导向剂,通过原位氧化聚合吡咯法制备了聚吡咯/海藻酸钠(PPy/SA)纳米球.聚吡咯/海藻酸钠纳米球的形貌和结构通过扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱进行表征.材料的电化学性能通过循环伏安法和恒电流充放电方法进行测试.电化学测试表明,聚吡咯/海藻酸钠纳米球在1 mol L-1KCl电解液中,电流密度为1 A g-1时其比电容高达347 F g-1.与纯聚吡咯相比较,聚吡咯/海藻酸钠纳米球具有更优异的循环稳定性能.     

聚吡咯改性层状黏土/聚己内酯抗菌纳米复合材料的制备与性能

利用Fe³⁺引发吡咯（Py）在层状双羟基金属氧化物（LDHs）表面发生氧化反应,形成聚吡咯（PPy）包覆LDHs（LDHs@PPy）;以LDHs@PPy和聚己内酯（PCL）为原料,采用溶液浇筑方法制备LDHs@PPy/PCL纳米复合薄膜.研究结果表明,LDHs@PPy对大肠杆菌和金黄色葡萄球菌的抗菌率均达到99.7%,其与基材PCL界面相容性良好,而且在基材中还具有异相成核作用.当LDHs@PPy的质量分数仅为1%时,LDHs@PPy/PCL纳米复合材料的拉伸强度和断裂伸长率分别增加35%和23%,氧气渗透性降低幅度达到56%,对大肠杆菌和金黄色葡萄球菌的抗菌率均超过99.99%,表现出良好的抗菌活性,拓展了层状黏土/生物基高分子复合材料在活性包装领域的应用.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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 substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.