SYNTHESIS OF CONDUCTIVE POLYANILINE VIA OXIDATION BY MnO2

A unique process of chemical oxidation polymerization of aniline using manganese dioxide (MnO2) as the oxidizing agent in an aqueous medium is described. The reaction between aniline and MnO2 follows a mechanism by which the organic monomer is oxidized while the metal oxide undergoes reductive dissolution. The effects of the amount of oxidizing agent and aniline, pH and temperature of the reactive system, type of acid on the yield and conductivity of polyaniline are discussed. The resulting polyaniline was characterized by [R and UV-Vis spectrometry. Polyaniline with a conductivity of 12.5 S/cm was obtained using 0.033 tool of aniline oxidized by 0.023 tool MnO2 in the presence of 100 mL of 2.7 mol/L HCI at 25℃ for 4 h.     

Minimization of mass interferences in quadrupole inductively coupled plasma mass spectrometric (ICP-MS) determination of palladium using a flow injection on-line displacement solid-phase extraction protocol

A flow injection on-line displacement solid-phase extraction protocol was employed to minimize mass interferences with determination of palladium by inductively coupled plasma mass spectrometry (ICP-MS). The developed method involved in on-line complexing of Ag⁺ with pyrrolidine dithiocarbamate (PDC), presorption of the resultant Ag–PDC onto a microcolumn packed with the cigarette filter, displacement sorption of Pd²⁺ through loading the sample solution onto the microcolumn due to on-line displacement reaction between Pd²⁺ and the presorbed Ag–PDC, elution of the retained Pd²⁺ with 50 μL of ethanol for on-line ICP-MS detection. Interferences from co-existing heavy metal ions with lower stability of their PDC complexes relative to Ag–PDC were minimized/eliminated. No interferences from 5 mg L^− 1 Zn and 3 mg L^− 1 Pb for ¹⁰⁴Pd, 0.4 mg L^− 1 Cu for ¹⁰⁵Pd, 6 mg L^− 1 Zn and 2 mg L^− 1 Cd for ¹⁰⁶Pd, 6 mg L^− 1 Zn and 3 mg L^− 1 Cd for ¹⁰⁸Pd, and 2 mg L^− 1 Cd for ¹¹⁰Pd were observed for the determination of 100 ng L^− 1 Pd. The enhancement factors of 71–75, sample throughput of 23 samples h^− 1 and detection limits of 2.8–3.5 ng L^− 1 were achieved with the consumption of 3.0 mL of sample solution. The precision (RSD) for eleven replicate determinations of Pd at the 100 ng L^− 1 level was 1.8–2.7%. The developed method was applied to the determination of palladium in rock samples.     

Solid electrolyte of fully conjugated,water–soluble rigid-rod polymer with articulated backbone for isotropic ionic conductivity

An intractable and fully conjugated, aromatic, heterocyclic rigid-rod polymer poly[1,7-dihydrobenzo[1,2-d:4,5-d′]diimidazo-2,6-diyl-(2-sulfo)-p-phenylene] (sPBI) was derivatized with isophthalic acid for an articulated rigid-rod polymer asPBI. This molecular backbone alternation significantly changed the intrinsic viscosity [η] of sPBI from 9.4 dL/g to 1.1 dL/g for asPBI containing minute (1/50 molar ratio) articulation moiety indicating more a coil-like polymer for asPBI. Both sPBI and asPBI were reacted with 1,3-propanesultone in dimethylsulfoxide containing lithium hydroxide for water–soluble polyelectrolytes sPBI-Li⁺ and asPBI-Li⁺, respectively. The polyelectrolytes were dissolved in aqueous solution with up to 5 wt.% of LiI dopant and cast into films. Direct-current conductivity (σ) was measured at room-temperature parallel to the film surface yielding σ_∥=3.2 × 10⁻³ S/cm and 2.8 × 10⁻³ S/cm for sPBI-Li⁺ and asPBI-Li⁺ (1/15), respectively. X-ray scattering and electron microscopy suggested that the cast films of sPBI-Li⁺ was in-plane isotropic but out-of-the plane anisotropic, and of asPBI-Li⁺ was three-dimensionally isotropic. It suggested that cast films of asPBI-Li⁺ having articulated backbone acquired an isotropic microstructure as well as an isotropic room-temperature σ superior to those of other solid polyelectrolytes.     

Chiral base-catalyzed aldol reaction of trimethoxysilyl enol ethers: effect of water as an additive on stereoselectivities

An aldol reaction of trimethoxysilyl enol ether catalyzed by lithium binaphtholate is described. The aldol reaction of trimethoxysilyl enol ether derived from cyclohexanone under anhydrous conditions predominantly afforded the anti-aldol adduct with moderate enantioselectivity, whereas the reaction under aqueous conditions predominantly resulted in the syn-adduct and the enantioselectivity of the syn-adduct was considerably improved. The best enantioselectivity was obtained in the reaction of trimethoxysilyl enol ether derived from 1-indanone with cyclohexanecarboxaldehyde (97% ee (syn)). This is the first example of an aldol reaction of trimethoxysilyl enol ether catalyzed by a chiral base.     

The fragmentation reaction of 16R-bromopregnane-3S,20S-diol

16R-Bromopregnane-3S,20S-diol reacted with potassium t-butoxide to afford androst-16-en-3S-ol in a moderate yield via fragmentation reaction. The latter is a key intermediate for the synthesis of 5α-androst-16-en-3-one, as boar sex pheromone, and other steroidal drugs. In addition, 16R,20S-epoxypregnane-3S-ol was also obtained as a major product by changing the reaction solvent.     

Determination of levodopa methyl ester and its metabolites in rat serum by CZE with amperometric detection

A reliable and reproducible method, capillary zone electrophoresis with amperometric detection (CZE–AD), has been developed for separation and quantification of levodopa methyl ester (LDME) and its biotransformation products levodopa (L-DOPA) and dopamine (DA) in rat serum. A carbon-disk electrode was used as working electrode. The optimum conditions for CZE detection were 50 mmol L^–1 phosphate solution at pH 7.0 as running buffer, 17 kV as separation voltage, 1.0 V (vs Ag/AgCl, 3.0 mol L^–1) as detection potential, and sample injection for 8 s at 17 kV. The linear ranges were from 2.4×10^–2 to 2.2 g mL^–1 for LDME, 2.9×10^–1 to 49.5 g mL^–1 for L-DOPA, and 1.4×10^–2 to 1.5 g mL^–1 for DA with correlation coefficients of 0.9997, 0.9994, and 0.9999, respectively. The detection limits for LDME, L-DOPA, and DA were 14.6, 98.0, and 9.7 ng mL^–1, respectively. Recoveries were 80.3% for LDME, 93.5% for L-DOPA, and 86.5% for DA. This method was applied to serum samples after intravenous injection of LDME and L-DOPA to rats.     

α-乙酰氧基-N-亚硝基吡咯烷的解离及其致癌代谢机理的理论研究

用ab initio方法, 在MP2/6-31G**水平下讨论了α-乙酰氧基-亚硝基吡咯烷(α-Acetoxy-NPYR)在各种条件下的解离反应机理, 并对形成终致癌物B, C, D的代谢机理进行研究. 发现在OH^－和H₂O作用下的解离都遵循羟基进攻羰基机理, OH^－作用下是一个经四面体中间体阴离子的无位垒过程, H₂O作用下有相对高的活化能(165.36 kJ/mol). H₃O^＋作用下是先形成阳离子产物的S_N1过程, 并没有发现遵循两种综合的解离情形. 同时, 羟基化产物异构化为终致癌物B, C, D是一个相对容易进行的过程.     

烷基紫精/五氧化二钒插层化合物的组装、表征及磁性的研究

以烷基紫精(alkylviologens; 又称紫精或紫罗精)为有机客体、层状五氧化二钒为无机主体, 在液、固两相反应体系中, 利用I^－与V^5＋的氧化还原反应, 使烷基紫精阳离子通过静电引力作用进入被还原的五氧化二钒层板之间, 形成一系列新颖的无机-有机插层化合物. 并运用X射线粉末衍射(XRD)、红外(FT-IR)、X射线光电子能谱(XPS)、紫外-可见漫反射(UV-vis DRS)等方法对其进行了表征. XRD分析结果证明, 五氧化二钒的层间距随着烷基紫精中烷基链的增长而增大, 但其结晶度随着烷基紫精阳离子中烷基链的增加而降低. XPS研究表明, 该类材料中的钒是以V^4＋和V^5＋两种混合价态存在, 氧原子处于三种不同的化学环境, 这些现象说明烷基紫精阳离子的引入对五氧化二钒的骨架结构影响不大, 主体五氧化二钒的层状结构保存完好; 氮原子处于两种不同的化学环境, 证实插层化合物中主客体之间相互修饰的协同效应, 有可能起到了稳定客体分子激发态的作用, 同时FT-IR光谱中芳香环特征谱带强度的变化也进一步证明了这一结论. UV-vis DRS分析发现由于主客体的相互作用使插层化合物在紫外和可见光区域产生特殊的光吸收性质. 从磁性研究的结果可以看出, 在温度低于15 K时, 插层化合物RV2为反铁磁性的有序结构; 当温度高于15 K时, 转变为顺磁性, 表现出磁无序结构.     

稀土酰基吡唑啉酮邻菲咯啉配合物的合成、表征及其生物活性

以稀土、邻菲咯啉、1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮为原料在无水乙醇溶液中反应，制备了一类新型稀土三元配合物，通过元素分析、摩尔电导、基质辅助激光解析/电离质谱、 ¹H核磁共振谱、红外光谱、拉曼光谱、紫外光谱、热重-差热分析及电子显微镜等手段对其进行了表征，确定了该配合物的化学组成:RE(PMBP)₃Phen(RE=Sm³⁺，Eu³⁺，Y³⁺，Er³⁺，Gd³⁺)，抗菌实验结果表明，稀土三元配合物对大肠杆菌、金黄色葡萄球菌和白色念珠菌有较强的抑制作用，抗菌谱广。通过MTT比色法对配合物诱导癌细胞凋亡能力做了初步研究，结果表明其具有较强的抑杀癌细胞的作用。