咪唑六氟磷酸盐聚离子液体凝胶电解质的辐射合成及性能研究

以1-乙烯基-3-烷基咪唑六氟磷酸盐C_nvimPF_6(n=6,12)为单体,(1,6-亚己基)-双(3-乙烯基咪唑)六氟磷酸盐为交联剂,六氟磷酸锂为添加剂,混合碳酸酯为溶剂,采用辐射引发聚合、交联合成了新型的聚离子液体凝胶电解质(简称PC_nvimPF_6-Li GPE),并研究了离子液体单体侧链长度、单体浓度、交联剂含量对PC_nvimPF_6-Li GPE性能的影响.结果表明所合成的PC_nvimPF_6-Li GPE具有良好的力学性能和高离子电导率,最大离子电导率可达7.18 mS/cm.     

五种1-烷基-2,3-二甲基咪唑型离子液体的合成及作为Li/LiFeO4电池电解液的研究

合成了五种新的1-烷基-2,3-二甲基咪唑二(三氟甲基磺酰)亚胺离子液体(alkyl-DMimTFSI).以离子液体作为Li/LiFeO4电池电解液,分别考察不同烷基(正丁基、正戊基、正辛基、异辛基和正癸基)对电解液理化性质、界面性质和电池行为的影响.结果表明离子液体的电化学窗口都可以达到5.6V(-0.4～5.2Vvs.Li+/Li),显示它们具有较好的电化学稳定性.加入碳酸亚乙烯酯作为添加剂后,离子液体电解液在Li负极形成稳定的固体电解质相界面膜(SEI),从而提高了Li负极的稳定性,保护了Li片不受腐蚀.电化学阻抗和循环伏安分析进一步揭示LiFeO4正极与离子液体电解液也有良好的兼容性.此外,研究还表明离子液体中烷基种类严重影响它们的电池行为.采用butyl-DMimTFSI和amyl-DMimTFSI电解液体系的电池充放电容量和可逆性明显优于另外三种离子液体,它们的首次放电容量分别达到145和152.6mAh/g,并表现出良好的充放电循环性能.因粘度最大,采用isooctyl-DMimTFSI电解液的电池首次放电容量仅为8.3mAh/g,但添加碳酸丙烯酯(质量比1∶1)稀释后首次放电容量上升至132.4mAh/g.     

离子液体1-烷基-3-甲基咪唑四氟硼酸盐在水溶液中的聚集行为

采用等温滴定量热法、静态荧光猝灭法和电导法系统研究了典型离子液体1-烷基-3-甲基咪唑四氟硼酸盐([Cnmim][BF₄])在水溶液中的聚集行为, 获得了胶束形成的临界胶束浓度(cmc), 摩尔焓变(ΔH_mic), 摩尔吉布斯自由能变(ΔG_mic), 摩尔熵变(ΔS_mic)以及不同浓度时[Cnmim][BF₄]胶束的平均聚集数等基本参数. 发现这类离子液体的聚集为熵驱动, 阳离子的烷基链越长, ΔG_mic越负, 聚集更容易发生. 此外, 结合[C_nmim]X (X=Cl^-, Br^-)的相关研究发现, 阳离子相同时, 体积越大和疏水性越强的阴离子与头基的结合能力越强, 能有效地降低头基之间的静电排斥, 降低cmc, 利于胶束的形成. 对于[C₁₂mim][BF₄], 添加剂β-环糊精(β-CD)的加入可使cmc增大, ΔH_mic和ΔS_mic减小, 而KBF₄则可使cmc和ΔH_mic减小, ΔS_mic增大.     

添加剂对离子液体凝胶聚合物电解质电化学性能的影响

本文采用1-乙基-3-甲基咪唑六氟磷酸盐(EMIPF₆)、六氟磷酸锂(LiPF₆)和偏氟乙烯-六氟丙烯共聚物(P(VdF-HFP))为原料制得P(VdF-HFP)-EMIPF₆-LiPF₆体系离子液体凝胶聚合物电解质,选取碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)以及碳酸乙烯酯(EC)和碳酸丙烯酯(PC)混合物(EC-PC)作为离子液体凝胶聚合物电解质的添加剂,分别研究了它们对聚合物电解质膜电化学性能的影响。结果表明：加入EC-PC的P(VdF-HFP)-EMIPF₆-LiPF₆电解质膜的电化学窗口达到4.6 V,锂离子迁移数为0.44,30 ℃时离子电导率为1.65 mS·cm^-1;而DEC、DMC、EMC对电解质膜的电化学稳定性、锂离子迁移数存在不良的影响,对离子电导率的提高不明显。研究了正极材料LiCoO₂在P(VdF-HFP)-EMIPF₆-LiPF₆+EC-PC电解质中的充放电循环性能,其首次放电比容量达到116.5 mAh·g^-1,充放电20次后,电池容量没有明显衰减。     

1-异丁基-3-甲基咪唑四氟硼酸盐离子液体在呕吐毒素酶联免疫检测中的应用研究

合成了一种水溶性离子液体1-异丁基-3-甲基咪唑四氟硼酸([i-Bmim]BF4),将其用于呕吐毒素(DON)的酶联免疫检测,结果表明,当体系中[i-Bmim]BF4的浓度为0.014 g/mL时,其定量下限为 1.41 μg/L,比不含该离子液体体系的定量下限4.57 μg/L提高了约69%;半数抑制浓度为30.20 μg/L;重复测定多次,其半数抑制浓度平均值为29.71 μg/L,相对标准偏差为3.26%;用T-2毒素代替DON进行了特异性试验,结果显示,不含离子液体体系中DON与T-2毒素、NIV的交叉反应率相对较高(分别为20.1%、14.9%),而含有0.014 g/mL该离子液体体系中DON与T-2毒素、NIV的交叉反应率分别为15.3%、10.2%.方法用于啤酒和麦芽汁中DON加标回收率的测定,实验表明,当体系中[i-Bmim]BF4浓度为0.014 g/mL,DON的加标浓度分别为50、70 mg/L时,其样品加标回收率均为98%,相对标准偏差分别为2.96%、6.02%.     

1-乙基-3-甲基咪唑四氟硼酸盐离子液体的量子化学研究

The results of the quantum chemistry study of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM+BF4-) were reported. The ab initio method and density functional theory (B3LYP method) was used to optimize the stable structure of the gas phase ion pair at the level of 6-311++G** basis set, respectively. An IR spectra for EMIM+BF4- were obtained through the vibrational analysis. The changes of atomic charge assignments have been investigated using the Natural Bond Orbital method. The computational results show that there exist hydrogen bonds and other weak interactions between the cation and the anion. Using counterpoise correction method to estimate the basis set superposition error, the interaction energy between the cation and anion is 346.78 kJ/mol.     

1-烷基-3-甲基咪唑氯化物焓变的热重分析

The structures of ionic liquids (ILs) based on 1-alkyl-3-methylimidazolium chloride [C_nmim]Cl (n = 2, 4, 6), (1-ethyl-3-methylimidazolium chloride [C₂mim]Cl, 1-butyl-3-methylimidazolium chloride [C₄mim]Cl, and 1-hexyl-3-methylimidazolium chloride [C₆mim]Cl) were elucidated by ¹H NMR and ¹³C NMR experiments. The vaporization characteristics of these ILs were studied by thermogravimetric analysis. Dynamic and isothermal thermogravimetric experiments were conducted in this study. The purpose of the dynamic experiments was to determine the initial decomposition temperature of the experimental sample and the temperature range for the isothermal thermogravimetric experiments. The purpose of the isothermal experiments was to record the mass dependence of the sample on time in the experimental temperature range. The Langmuir equation and Clausius-Clapeyron equation were used to fit the experimental data and obtain the vaporization enthalpies of these ILs at the average temperature within the experimental temperature range. However, in order to expand the applicability of the estimated values and to compare them with the literature data, the vaporization enthalpy ΔH_vap(T_av) measured at the average temperature was converted into vaporization enthalpy ΔH_vap(298) at ambient temperature. The difference between the heat capacities of the ILs in the gaseous and liquid states at constant pressure, Δ_l^gC_pm^ө proposed by Verevkin, was used in this conversion process. The experimental data for substance density and surface tension at other temperatures were obtained by referring to the literature. In addition, the data for density and surface tension at T = 298.15 K were obtained by applying the extrapolation method to the literature values for other temperatures. The vaporization enthalpy of the 1-octyl-3-methylimidazolium chloride IL [C₈mim]Cl was estimated by using the new vaporization model we had proposed in our previous work and compared with the reference value. The estimated value for [C₈mim]Cl was on the same order of magnitude as the reference value. We compared the vaporization enthalpies in the present study with those for the carboxylic acid imidazolium and amino acid imidazolium ILs ([C_nmim]Pro (n = 2-6) and [C_nmim]Thr (n = 2-6), respectively in our previous work. The results revealed that a change in the anion type affects the vaporization enthalpy of the ILs in the order amino acid imidazolium > carboxylic acid imidazolium > halogen imidazolium, when the cation is the same. Considering the structural differences between the three kinds of ILs, the abovementioned order may be related to the intermolecular hydrogen bonds. There were no intermolecular hydrogen bonds in the [C_nmim]Cl (n = 2, 4, 6) ILs studied here. Therefore, the vaporization enthalpy of [C_nmim]Cl (n = 2, 4, 6) was the lowest among the three kinds of ILs considered.     

1-烯丙基-3-甲基咪唑离子液体单体与丙烯腈共聚行为的研究

以1-烯丙基-3-甲基咪唑盐酸盐([AMIM]Cl)作为离子液体单体,偶氮二异丁腈作为引发剂,二甲基亚砜为溶剂,实现了与丙烯腈(AN)在不同反应条件下的自由基共聚合.研究了AN/[AMIM]Cl二元共聚合的动力学,得到了相应的竞聚率数据(rAN=8.11,r[AMIM]Cl=0).用1H-NMR、GPC、DSC、TGA等手段对共聚物进行了表征.通过对AN/[AMIM]Cl二元共聚及AN/IA/[AMIM]Cl三元共聚的研究发现,[AMIM]Cl在与丙烯腈共聚时具有双重作用,一部分离子单体进入到共聚物的分子链中调节其亲水性及可纺性,剩下的大部分留在纺丝液中可显著降低纺丝液的黏度,从而使高分子量高固含量纺丝液的纺制成为可能,有望得到高性能的碳纤维原丝.     

新型温控离子液体介质中脂肪酶催化合成乙酸苯乙酯

 设计合成了三种同分异构离子液体 1,3-二正戊基咪唑六氟磷酸盐 ([D(n-C5)Im]PF6)、1,3-二异戊基咪唑六氟磷酸盐 ([D(i-C5)Im]PF6) 和 1,3-二 (2-甲基丁基) 咪唑六氟磷酸盐 ([D(2-mb)Im]PF6). 以假单胞菌脂肪酶 Pseudomonas cepacial 催化合成乙酸苯乙酯为模型反应, 分别考察了反应介质对酶行为的影响. 结果发现, 酶在离子液体[D(2-mb)Im]PF6 中的活性及反应性能明显高于有机溶剂正己烷. 基于[D(2-mb)Im]PF6 离子液体的温控特点, 提出了一种高温反应与低温分离相结合的乙酸苯乙酯合成路线. 通过优化实验, 得到合成乙酸苯乙酯的最佳反应条件为: 30 mg 酶, 1.0 g 离子液体, 2% 含水量, 反应温度 35 oC, 反应时间 48 h. 此时, 乙酸苯乙酯产率达 92.3%. 脂肪酶在[D(2-mb)Im]PF6 中的稳定性是在正己烷中的 7.4 倍, 且重复使用 10 次后催化活性没有明显降低. 此外, 采用圆二色谱和内源荧光光谱法研究了不同介质中脂肪酶结构的变化. 结果表明, 脂肪酶在[D(2-mb)Im]PF6 中有较大的氨基酸残基裸露程度和良好的二级结构稳定性.     

1-烷基-3-甲基咪唑l-乳酸盐的合成及其物理性质

离子液体;手性离子液体;烷基甲基咪唑l-乳酸盐     

Viscosity of ionic liquid mixtures of 1-alkyl-3-methylimidazolium hexafluorophosphate + CO2

The viscosities of the mixtures 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF₆]) + CO₂ and 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF₆]) + CO₂ were measured with a rolling ball viscometer. The CO₂ mole fraction for one mixture ranged up to 0.434 and the other up to 0.447. The viscosities were measured at 293.15-353.15 K and 10-20.0 MPa. The experimental uncertainty in viscosity was estimated to be within ±3.0%. The experimental data were compared with McAllister's three-body model, which correlated with the experimental data within average absolute deviations of 5.9%.     

Selective extraction/isolation of hemoglobin with ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate (BtmsimPF6)

Ionic liquid was for the first time employed for selective isolation of heme-protein species. Direct extraction of hemoglobin into ionic liquid without using any concomitant reagent or extractant was carried out. Hemoglobin at the level of 100 ng μL⁻¹ could readily be quantitatively extracted into ionic liquid (IL) 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate (BtmsimPF₆) in the absence of any co-existing extractants/additives at pH 7, at the same time; however, the other protein species do not interfere and remain in the aqueous phase. A back extraction efficiency of ca. 80% for 20 ng μL⁻¹ hemoglobin in ionic liquid phase was achieved with sodium dodecyl sulfate (SDS) solution as stripping reagent. ⁵⁷Fe Mossbauer spectra and circular dichroism (CD) spectra indicated that the penta-coordinated ferrous atom in hemoglobin provide a vacant or free coordinating position, which could be occupied by the cationic Btmsim⁺ moiety. The interaction/coordination reaction between the iron atom in the heme group of hemoglobin and the cationic ionic liquid moiety furnishes the driving force for facilitating fast transfer of hemoglobin into BtmsimPF₆. The present system was applied for selective isolation of heme-protein, i.e., hemoglobin from human whole blood without any pretreatment, giving rise to satisfactory results.     

Use of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate in countercurrent chromatography

Room temperature ionic liquids (RTIL) are molten salts that are liquids at room temperature. Their liquid state makes them possible candidates as solvents in countercurrent chromatography (CCC), which uses solvents as both the mobile and stationary phases. The study focuses on 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF₆), an easy to synthesize and purify RTIL whose melting point is –8°C. It is shown that BMIM PF₆ behaves like a solvent of significant polarity (comparable with that of ethanol). The ternary phase diagram water–acetonitrile–BMIM PF₆ is given, because it was necessary to add acetonitrile to reduce the ionic liquid viscosity. The 40:20:40% w/w water–acetonitrile–BMIM PF₆ biphasic liquid system was found to be appropriate as a biphasic liquid system for CCC. Different aromatic solutes, including bases, acids, and neutral compounds, were injected into the CCC column to estimate their distribution constants between the ionic liquid-rich phase and the aqueous phase. The resulting K_il/w constants were compared with the corresponding literature octanol–water partition coefficients, K_o/w. The important drawbacks in the use of RTIL in CCC are clearly pointed out: high viscosity producing pressure build-up, UV absorbance limiting the use of the convenient UV detector, and non-volatility precluding the use of the evaporative light-scattering detector for continuous detection.     

Physical and electrochemical properties of 1-alkyl-3-methylimidazolium tetrafluoroborate for electrolyte

Three kinds of ionic liquids, 1-alkyl-3-methylimidazolium tetrafluoroborate (n=2–4), were prepared and fundamental properties of ionic liquids and those mixed with industrially used organic solvents (PC, GBL and AN) were investigated compared to solid salts, TEMABF₄. It was found that degree of ionization of the ionic liquids were almost same as that of TEMABF₄ from the conductivity measurement in diluted system of PC. The ionic liquids and the organic solvents intermingle with each other. Some enhancement in conductivity was observed compared to TEMABF₄.     

Measurement and correlation of solubility of carbon dioxide in 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids

The solubility of carbon dioxide in the ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate and 1-nonyl-3-methylimidazolium hexafluorophosphate was measured at temperatures of 293.15 and 298.15 K and pressure up to 4 MPa using a stoichiometric phase equilibrium apparatus. The measured data for 1-butyl-3-methylimidazolium hexafluorophosphate were in good agreement with existing literature data and new solubility data were reported for 1-nonyl-3-methylimidazolium hexafluorophosphate. The measured data were correlated using the group contribution non-random lattice fluid equation of state (GC-NLF EoS) proposed by Lee and co-workers. The group parameters for CG-NLF EoS were slightly modified at limited range to accommodate recent experimental data and better prediction at high pressure and long alkyl chains.     

Room temperature ionic liquid as a novel medium for liquid/liquid extraction of metal ions

Room temperature ionic liquids (RTILs) have been used as novel solvents to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. The hydrophobic character and water immiscibility of certain ionic liquids allow their use in solvent extraction of hydrophobic compounds. In this work, a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆], was used as an alternative solvent to study liquid/liquid extraction of heavy metal ions. Dithizone was employed as a metal chelator to form neutral metal-dithizone complexes with heavy metal ions to extract metal ions from aqueous solution into [C₄mim][PF₆]. This extraction is possible due to the high distribution ratios of the metal complexes between [C₄mim][PF₆] and aqueous phase. Since the distribution ratios of metal dithiozonates between [C₄mim][PF₆] and aqueous phase are strongly pH dependent, the extraction efficiencies of metal complexes can be manipulated by tailoring the pH value of the extraction system. Hence, the extraction, separation, and preconcentraction of heavy metal ions with the biphasic system of [C₄mim][PF₆] and aqueous phase can be achieved by controlling the pH value of the extraction system. Preliminary results indicate that the use of [C₄mim][PF₆] as an alternate solvent to replace traditional organic solvents in liquid/liquid extraction of heavy metal ions is very promising.     

A novel microextraction technique based on 1-hexylpyridinium hexafluorophosphate ionic liquid for the preconcentration of zinc in water and milk samples

A simple dispersive liquid-liquid microextraction methodology based on the application of 1-hexylpyridinium hexafluorophosphate [HPy][PF₆] ionic liquid (IL) as an extractant solvent was proposed for the preconcentration of trace levels of zinc as a prior step to determination by flame atomic absorption spectrometry (FAAS). Zinc was complexed with 8-hydroxyquinoline (oxine) and extracted into ionic liquid. Some effective factors that influence the microextraction efficiency such as pH, oxine concentration, amount of IL, ionic strength, temperature and centrifugation time were investigated and optimized. In the optimum experimental conditions, the limit of detection (3 s) and the enhancement factor were 0.22 μg L⁻¹ and 71, respectively. The relative standard deviation (RSD) for six replicate determinations of 13 μg L⁻¹ Zn was 1.92%. In order to validate the developed method, a certified reference material (NIST SRM 1549) was analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the trace determination of zinc in water and milk samples.     

PdNi- and Pd-coated electrodes prepared by electrodeposition from ionic liquid for nonenzymatic electrochemical determination of ethanol and glucose in alkaline media

Nonenzymatic electrochemical determination of ethanol and glucose was respectively achieved using PdNi- and Pd-coated electrodes prepared by electrodeposition from the novel metal-free ionic liquid (IL); N-butyl-N-methylpyrrolidinium dicyanamide (BMP-DCA). BMP-DCA provided an excellent environment and wide cathodic limit for electrodeposition of metals and alloys because many metal chlorides could dissolve in this IL where the reduction potentials of Pd(II) and Ni(II) indeed overlapped, leading to the convenience of potentiostatic codeposition. In aqueous solutions, the reduction potentials of Pd(II) and Ni(II) are considerably separated. The bimetallic PdNi coatings with atomic ratios of ∼80/20 showed the highest current for ethanol oxidation reaction (EOR). Ethanol was detected by either cyclic voltammetry (CV) or hydrodynamic amperometry (HA). Using CV, the dependence of EOR peak current on concentration was linear from 4.92 to 962 μM with a detection limit of 2.26 μM (σ = 3), and a linearity was observed from 4.92 to 988 μM using HA (detection limit 0.83 μM (σ = 3)). The Pd-coated electrodes prepared by electrodeposition from BMP-DCA showed electrocatalytic activity to glucose oxidation and CV, HA, and square-wave voltammetry (SWV) were employed to determine glucose. SWV showed the best sensitivity and linearity was observed from 2.86 μM to 107 μM, and from 2.99 mM to 10.88 mM with detection limits of 0.78 μM and 25.9 μM (σ = 3), respectively. For glucose detection, the interference produced from ascorbic acid, uric acid, and acetaminophen was significantly suppressed, compared with a regular Pt disk electrode.     

Electroanalytical quantification of total dsDNA extracted from human sample using,an ionic liquid modified,carbon nanotubes paste electrode

Direct electrochemistry of dsDNA has been achieved by using an ionic liquid 1-butyl-4-methylpyridinium hexafluorophosphate modified carbon nanotubes paste electrode (IL-CNTPE). Oxidation peaks appeared at 0.93 and 1.26 V (vs. Ag/AgCl) on the IL- CNTPE after preconcentration of dsDNA in pH 5.0 acetate buffer, which were attributed to the oxidation of guanine and adenine residues on the dsDNA molecule structure. Based on the signal of guanine, under the optimal conditions, very low levels of dsDNA can be detected after 60 s accumulation with detection limits of 0.249 mg L⁻ 16 pM. Additionally, human DNA from a healthy volunteer is determined by use of the IL-CNTPE and it is found to be 40 ± 2, 14 pM.     

1-烷基-3-甲基咪唑溴化盐离子液体的晶体结构及性能

以不同链长溴代烷烃和N-甲基咪唑反应得到1-烷基-3-甲基咪唑溴化盐,用元素分析和核磁共振对化合物进行了表征.室温下用溶剂蒸发法得到了单晶,并用X射线单晶衍射法测定了晶体结构,该晶体属于三斜晶系,空间群为P-1.化合物采用双分子层结构,水分子参与结构的形成,整个化合物由交叉的线性烷基链、咪唑头基、溴离子和水分子组成,溴离子和水分子之间较强的氢键作用在(010)方向上形成了一个无限的O-H···Br氢键链.用偏光显微镜、差示扫描量热(DSC)技术研究了其液晶行为,证明其一水合物为近晶相热致液晶.液晶区域的温度范围较宽说明水分子起到稳定作用.