尺寸可控的聚苯胺复合微球的电纺制备与表征

以十二烷基苯磺酸(DBSA)掺杂的导电聚苯胺与聚乙二醇(PEG)及Fe3O4的混合氯仿溶液,采用静电纺丝(spinning technology)方法制备含Fe3O4纳米颗粒的导电聚苯胺(PANI)/PEG/Fe3O4复合微球.SEM结果表明,电纺所得的PANI/PEG/Fe3O4复合微球结构依赖于PEG聚合物浓度、静...     

膨胀石墨/聚苯胺/Fe_3O_4复合材料的制备及吸波性能

采用原位聚合方法制备了膨胀石墨/聚苯胺(EG/PANI)复合材料,将Fe_3O_4负载于EG/PANI表面,得到具有电磁吸收性能的EG/PANI/Fe_3O_4复合材料.通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)及矢量网络分析仪(VNA)等对复合材料的形貌、成分和吸波性能进行了研究.吸波性能分析结果表明,当掺杂浓度为0.05 mol/L,匹配厚度d=2 mm时,样品的最小反射损耗(RLmin)在8.64 GHz处达到-37 dB.随着掺杂浓度的增加,最小反射损耗峰向低频移动,对应的匹配厚度逐渐变厚.材料的介电弛豫极化、涡流损耗及λ/4模型的干涉相消现象出现的双峰,使EG/PANI/Fe_3O_4复合材料在电磁波吸收领域有一定的应用前景.     

TiO_2聚苯胺复合膜的光电化学

利用电化学方法制备了TiO2 聚苯胺 (PANI)复合膜 .该膜具有比TiO2 或PANI膜更宽的吸收谱区 ,并且不同于利用聚苯胺光敏化的TiO2 膜 ,表现为两者复合材料膜的性质 .扫描电镜图表明 ,TiO2 微粒不完全覆盖着PANI膜 .根据TiO2 微粒光电流谱带的阈值能可得复盖在部分氧化态聚苯胺膜上的TiO2 微粒的禁带宽度为 3.0eV .部分氧化态聚苯胺膜的光电流谱遵循Fowler定律 ( 1/2 ～hυ成线性 ) .通过Fowler图得出部分氧化态聚苯胺的绝缘母体禁带宽度为 3.33eV ,并证实该绝缘母体为还原态聚苯胺 .从Mott Schottky图得到在 0 .0 5mol/LK3Fe(CN) 6 /K4 Fe(CN) 6 溶液中 (pH =8.52 )部分氧化态聚苯胺的平带电位为 0 .13V ,掺杂浓度为 5.3× 10 18cm- 3;TiO2 PANI复合膜的平带电位为 - 0 .6 5V ,掺杂浓度为 9.1× 10 19cm- 3.解释了TiO2 PANI复合膜的光电化学过程并描绘出其能带图 .利用TiO2 PANI复合膜能够有效地光降解苯酚溶液 .     

配位-氧化聚合-水热法制备聚苯胺/CoFe_2O_4纳米复合物及其微波吸收性能

采用"配位-氧化聚合-水热法"制备了本征态聚苯胺/CoFe2O4二元纳米复合物,再以磺基水杨酸掺杂获得聚苯胺/CoFe2O4电磁复合物.考察了反应物配比及掺杂酸浓度对产物电磁性能的影响.通过透射电子显微镜(TEM)、X射线衍射(XRD)、红外光谱(FTIR)及电磁测量等手段对聚苯胺/CoFe2O4的形貌、结构及性能进行了表征.结果表明,复合物呈现多级结构,其中CoFe2O4为立方体状,平均粒径小于20 nm.当CoFe2O4的质量分数为8.86%时,复合物的电导率约为0.43 S/cm;当聚苯胺/CoFe2O4复合物厚度为2 mm时,在16.01 GHz处最大反射损耗为-16.71 dB,小于-10 dB的带宽达4.68 GHz;而当聚苯胺/CoFe2O4复合物厚度为3.2 mm时,在9.23 GHz处最大反射损耗达-51.81 dB,小于-10 dB的带宽为3.69 GHz,表明具有良好的吸波性能.     

聚苯胺/ZnFe_2O_4纳米复合物的制备与表征

以Fe(NO3)3·9H2O和Zn(NO3)2·6H2O为原料,采用改进的柠檬酸盐前驱物法合成了片状ZnFe2O4,进一步通过原位聚合反应得到了聚苯胺(PANI)/ZnFe2O4纳米复合物。利用X射线粉末衍射、扫描电子显微镜、透射电子显微镜、红外光谱以及荧光光谱等测试技术对其进行了表征。实验结果表明,通过原位聚合反应PANI沉积在片状ZnFe2O4表面。X射线粉末衍射和红外光谱进一步证实了PANI/ZnFe2O4纳米复合物的生成。ZnFe2O4的引入提高了PANI的荧光发光性能和热稳定性。     

硅磁微粒/聚苯胺复合物的制备及其对染料废水的吸附-降解性能

通过水热法制备碳微球、共沉淀法制备空心Zn Fe2O4和原位聚合法制备Zn Fe2O4/Si O2/PANI复合物,并表征其结构、形貌、组成和性质.结果表明,Si O2对铁氧体的包覆能提高二元复合物对染料废水的降解性能;铁氧体与二氧化硅物质的量比(nZn Fe2O4/nSi O2)为1:3的Zn Fe2O4/Si O2复合物对染料废水具有较好的降解作用;Zn Fe2O4/Si O2/PANI复合物对染料废水的光催化降解活性随苯胺质量分数(wAn)的增加而增大,当wAn为50%时,Zn Fe2O4/Si O2/PANI复合物对染料废水去除率高达98%.样品因具有磁性而回收方便,重复使用性能良好.     

新型质子酸掺杂聚苯胺的合成及其电化学电容行为

用化学氧化聚合法制得了草酸掺杂聚苯胺(H2C2O4-PANI)和柠檬酸掺杂聚苯胺(C6H8O7-PANI),并与盐酸掺杂聚苯胺(HCl-PANI)做了对比研究.用红外光谱(FT-IR)、X射线衍射(XRD)和透射电镜(TEM)对掺杂聚苯胺的结构和形貌进行了表征.用循环伏安,恒流充放电和交流阻抗测试对材料在1 mol/L HCl溶液中的电化学电容行为进行了研究.结果表明:3种酸掺杂的聚苯胺具有不同的空间结构,电化学性能也有差异.与盐酸和柠檬酸掺杂的聚苯胺相比,草酸掺杂制备的聚苯胺表现出更优良的电化学电容行为,单电极比电容可达670 F/g.     

聚苯胺/Co_(0.5)Zn_(0.5)Fe_2O_4纳米复合材料的制备及电磁性能

采用高分子凝胶法制备尖晶石型Co0.5Zn0.5Fe2O4,原位聚合法制备纯聚苯胺和聚苯胺/Co0.5Zn0.5-Fe2O4纳米复合材料.使用傅立叶红外光谱(FTIR)、紫外可见吸收光谱(UV-Vis)、X射线衍射仪(XRD)和透射电子显微镜(TEM)对复合材料进行了表征.FTIR和XRD的结果表明样品为纯聚苯胺和聚苯胺/Co0.5Zn0.5-Fe2O4.UV-Vis光谱表明聚苯胺/Co0.5Zn0.5Fe2O4苯环上的π-π*和n-π*分别红移了23nm和5nm.TEM照片可知,聚苯胺和聚苯胺/Co0.5Zn0.5Fe2O4粒子的平均粒径分别约为50nm和70nm.在8.2～12.4GHz测试频率范围内,聚苯胺/Co0.5Zn0.5Fe2O4的ε″数值在9.2～12.3之间,u″数值在0.15～0.16之间;聚苯胺/Co0.5-Zn0.5Fe2O4介电损耗低于纯聚苯胺,而磁损耗高于纯聚苯胺.     

Fe_3O_4@聚吡咯@聚苯胺核壳结构的制备及吸波性能

用聚吡咯(PPy)对溶剂热法制备的Fe_3O_4纳米颗粒进行表面修饰,再用聚苯胺(PANI)调控Fe_3O_4@PPy复合材料的电磁组成,制备出具有核壳结构的Fe_3O_4@PPy@PANI复合吸波材料.当PPy对Fe_3O_4纳米颗粒修饰后,PANI极易包覆在纳米颗粒表面.电磁性能分析结果表明,当苯胺(An)与Fe_3O_4@PPy质量比为1/4时,最小反射损耗值(RLmin)达到-39.2 d B;当An与Fe_3O_4@PPy的质量比为1/2时,反射损耗小于-10d B的频宽达到4.6 GHz.电磁成分比例对复合材料的吸波性能有较大的影响,随着聚苯胺含量的增加,电磁吸收呈现先增加后减小的趋势.     

手性聚苯胺纳米纤维的电化学制备

采用恒电位电聚合法制备了樟脑磺酸(CSA)掺杂的旋光异构性聚苯胺(PANI)纳米纤维. 用扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 紫外-可见吸收光谱(UV-Vis)和圆二色光谱(CD)对PANI纳米纤维的形貌和光学性质进行表征, 结合电聚合溶液胶束平均粒径和ζ电位的测定, 研究了具有旋光异构性PANI纳米纤维的形成机理和具有增强旋光异构性的原因. 所制备的PANI纳米纤维具有无双螺旋结构, 其形貌不随着苯胺浓度的改变而变化. 不同手性樟脑磺酸掺杂制备的PANI纳米纤维具有镜像对称的旋光异构性, 且具有较高的椭圆偏振率. 这种手性PANI纳米纤维的颜色和旋光性均可通过化学掺杂/去掺杂或电化学掺杂改变氧化还原态而呈现可逆变化.     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.