离子液体型表面活性剂研究

以1-甲基咪唑为原料, 制备了6个常规离子液体: 1-正丁基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[bmim][BF₄]及[bmim][PF₆])、1-正己基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[hmim][BF₄]及[hmim][PF₆])、1-正十六烷基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[C₁₆mim][BF₄]及[C₁₆mim][PF₆])和4个功能化离子液体: 1-(2-羟乙基)-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[2-hemim][BF₄]及[2-hemim][PF₆])、1-乙氧羰基甲基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[eocmmim][BF₄]及[eocmmim][PF₆]). 研究了这两类离子液体的一些物理性能, 旨在挖掘离子液体在香料香精化妆品工业中的应用价值. 分别检测了它们与一般溶剂的互溶性, 并测定了它们的表面张力和发泡性能, 实验结果表明, 仅[C₁₆mim][BF₄]和[C₁₆mim][PF₆]具有发泡性能, 发泡力分别为68和120 mm.     

咪唑类离子液体用作电解质对燃料电池性能的影响

为优化改善燃料电池的整体性能,在自由电解质燃料电池中,考察了五种咪唑类离子液体用作燃料电池电解质时对燃料电池性能的影响。结果表明,以氢气为燃料时,在相同电流密度下,电路电压和输出功率从高到低依次为1-丁基-3-甲基咪唑四氟硼酸盐 > 1-丁基-3-甲基咪唑六氟磷酸盐 > 氢氧化钠溶液 >> 氯化-1-丁基-3-甲基咪唑 > 溴化-1-丁基-3-甲基咪唑 > 1-丁基-3-甲基咪唑硫酸氢盐;以甲烷为燃料时,相同电流密度下,电路电压和输出功率从高到低则依次为溴化-1-丁基-3-甲基咪唑 > 1-丁基-3-甲基咪唑硫酸氢盐 > 氯化-1-丁基-3-甲基咪唑 > 氢氧化钠溶液> 1-丁基-3-甲基咪唑四氟硼酸盐 > 1-丁基-3-甲基咪唑六氟磷酸盐。以[Bmim]BF₄为氢气燃料电池电解质时,温度升高和离子液体中水含量增加,均会使燃料电池的性能减弱。     

水样中氟罗沙星和磺胺喹噁啉的离子液体均匀提取

提出一种新的离子液体均匀提取方法,即向水样中加入可溶于水的离子液体1-己基-3-甲基咪唑四氟硼酸盐([C6MimBF4]),再加入过量六氟磷酸铵(NH4PF6),形成不溶于水的离子液体1-己基-3-甲基咪唑六氟磷酸盐([C6MimPF6]),水样中的氟罗沙星和磺胺喹噁啉被提取到[C6MimPF6]相,离心分离后,离子液体可直接用于HPLC分析.本法测得的氟罗沙星和磺胺喹噁啉的检出限分别为1.8和1.1μg/L.     

离子液体增塑生物基聚丁内酰胺的热分解机理

采用疏水性1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)和亲水性1-丁基-3-甲基咪唑四氟硼酸盐 ([BMIM]BF₄)两种咪唑类离子液体(IL)增塑聚丁内酰胺(PBL), 探讨了IL对PBL结晶性能及热性能的影响. 研究发现, 两种IL都会削弱PBL分子间氢键, 并抑制PBL晶体在(200)晶面的生长, 降低PBL结晶度. 当IL添加质量分数为5%时, 增塑膜熔点下降7~8 ℃. 与纯PBL膜相比, [BMIM]BF₄增塑PBL膜热稳定性下降, 而[BMIM]PF₆增塑PBL膜的热稳定性提高. [BMIM]PF₆增塑PBL膜热分解过程的热动力学分析结果表明, 其热分解反应活化能为46.68 kJ/mol, 反应级数为1, 热分解最概然机理函数模型符合Mampel单行法则(一级), 即PBL受到热刺激后, 在聚合物和分解产物界面无规律成核, 反应核心具备反应活性, 随后反应逐步扩大, 直至结束.     

微波辅助离子液体合成法在亲核氟化中的应用

采用微波辅助合成法快捷、高效地制备了系列咪唑类和吡啶类离子液体,并对其在亲核氟化中的应用进行了研究.结果表明,N-苄基吡啶四氟硼酸盐([bepy]BF4)是一种稳定性高、使用效果好的离子液体.在微波作用下,以N-苄基吡啶四氟硼酸盐和乙腈为共溶剂,以氟化铯为氟化试剂,高效合成了系列含氟化合物.在优化反应条件下,其收率为54.1%～76.3%,反应时间较常规油浴加热最好时可缩短50%以上.     

基于电性距离矢量研究多氯联苯生物降解速率常数

通过多元线性回归和人工神经网络方法建立66种多氯联苯生物降解速率常数(K1)的定量构效关系(QSAR). 基于电性距离矢量(Mk),建立了lnK1的最佳三参数(M91、M25和M15)线性模型,其传统相关系数(R2)、交叉验证系数(Rcv2)分别为0.833、0.809。经R2、Rcv2、VIF、FIT、AIC检验,所建模型具有较强的稳定性和良好的预测能力. 将M91、M25、M15作为人工神经网络的输入层结点,采用3:10:1的网络结构,利用BP算法获得了一个令人满意的lnK1模型,训练集、验证集、测试集和总体的R2依次为0.991、0.995、0.997和 0.993。与多元线性回归模型相比,非线性lnK1-BP模型具有更好的预测能力。这两种回归方法相辅相成,线性回归方法为神经网络模型提供了具体的物理解释,而神经网络方法为线性模型提供了更准确的预测结果。     

氯酚化合物对发光细菌毒性的构效关系研究

本文对20种氯酚化合物进行DFT-B3LYP/6-311G**水平全优化计算,据所得量子化学参数构建其对发光细菌毒性的定量构效关系(QSAR)模型。经逐步多元回归分析后,所建立的QSAR模型的相关系数R及去一法(LOO)交互检验复相关系数R2cv分别为0.962和0.876;用预测集样本进行了外部预测,所得外部预测集交互检验Q2ext为0.961,表明所建立的QSAR模型具有较好的稳定性和较强的预测能力。结果表明:分子的体积愈大,化合物毒性愈强;最负非氢原子净电荷愈负,毒性愈强。对模型应用域(AD)进行了表征,所建立的模型可以应用于应用域内氯酚化合物对发光细菌毒性的预测,具有潜在应用价值。     

[EPy][BF4]和[EPy][PF6]离子对的气相及液相阴阳离子相互作用研究

采用从头算HF/6-31G和密度泛函理论B3LYP/6-31+G(d,p)方法, 对乙基吡啶四氟硼酸盐([EPy][BF4])和乙基吡啶六氟磷酸盐([EPy][PF6])的离子对进行了结构优化和频率分析, 并利用自洽反应场(SCRF)的导体极化连续模型(CPCM)考察了离子对液态下的结构及相互作用, 得到了两种离子对的红外光谱及气相、液相下最稳定结构. 由两种离子对的几何参数可知, 阴阳离子通过氢键相互作用, 两种离子液体的红外光谱特征值与实验值比较吻合. 应用自然键轨道(NBO)理论分析了吡啶阳离子及离子对中的原子电荷分布和电荷转移情况, 结果表明两种离子对中阴阳离子间存在静电相互作用和氢键作用. 通过几何参数、相互作用能及NBO分析研究发现, 液相下由于周围电荷的中和作用, 离子对中阴阳离子的相互作用明显降低.     

咪唑啉衍生物缓蚀剂的定量构效关系及分子设计

采用量子化学密度泛函理论(DFT)及线性回归分析方法, 对十一烷基咪唑啉衍生物缓蚀剂抗H2S、CO2腐蚀性能进行了定量构效关系(QSAR)研究. 通过回归分析, 筛选出了影响缓蚀剂缓蚀性能的主要因素, 建立了QSAR模型, 并使用留一法交叉验证对模型的稳定性及预测能力进行了分析. 结果表明, 电子转移参数△N、咪唑环上非氢原子静电荷之和∑Qring及分子极化率α对咪唑啉类缓蚀剂的缓蚀性能有很大的贡献, 所得模型的拟合相关系数(R2)和交叉验证相关系数(q2)分别为0.924 和0.917, 模型对此类缓蚀剂抗H2S、CO2腐蚀性能具有较好的预测效果. 应用QSAR研究结果进行了分子设计, 在理论上提出了一些具有较高抗H2S、CO2腐蚀性能的新型咪唑啉衍生物, 为实验工作者合成新型缓蚀剂提供理论参考.     

氟喹诺酮三唑酮衍生物抗增殖活性的CoMFA模型

应用比较分子力场分析法(CoMFA)研究了18种氟喹诺酮三唑啉酮衍生物对人白血病HL60细胞的体外抗增殖活性(pH)。建立的模型在高相关系数值(R2=0.969)和交叉验证系数值(R2cv=0.473)方面显示出良好的相关和预测能力。空间场和静电场对pH的贡献分别为58.5%和41.5%。基于CoMFA等高线图,揭示了该系列化合物抗增殖活性的一些关键结构因素,如疏水作用、空穴契合、库仑力及氢键等。这些结果为理解其作用机制、设计具有高抗增殖活性的新型氟喹诺酮三唑啉酮类化合物以及预测其活性提供了有益的理论参考。     

Peptide bond formation catalyzed by α-chymotrypsin in ionic liquids

α-Chymotrypsin catalyzed peptide bond formation was studied in ionic liquids using the synthesis of a protected fragment of Leu-enkephalin, ZTyrGlyGlyOEt, as model reaction. MOEMIM·PF₆ was found to be the most favorable solvent among the six different 1-alkyl-3-methylimidazolium hexafluorophosphates and tetrafluoroborates ionic liquids screened. With MOEMIM·PF₆ as reaction media, several di- or tripeptide derivatives were successfully prepared in 68-75% isolated yields.     

Dynamically coating the capillary with 1-alkyl-3-methylimidazolium-based ionic liquids for separation of basic proteins by capillary electrophoresis

Ionic substances with melting points close to room temperature are referred to as ionic liquids. Because ionic liquids are environmentally benign and are good solvents for a wide range of both organic and inorganic materials, interest for their potential uses in different chemical processes is increasing. In this paper, a capillary electrophoretic method for the analysis of basic proteins including lysozyme, cytochrome c, trypsinoge, and α-chymotyypsinogen A is reported. The method, in which 1-alkyl-3-methylimidazolium-based ionic liquids are used as the running electrolytes, leads to a surface charge reversal on the capillary wall. The effects of the alkyl group, imidazolium counterion, and the concentration of the ionic liquids were discussed. The optimum buffer system was a 90 mM 1-ethyl-3-methylimidazolium tetrafluoroborate (1E-3MI-TFB) solution. The applied voltage was −15 kV and detection was performed by monitoring absorbance at 240 nm. Baseline separation, high efficiencies, and symmetrical peaks of four proteins were obtained. The R.S.D. values of migration times and peak areas were <0.68 and <3.0%, respectively. The separation mechanism seems to involve association between the imidazolium cations and the proteins.     

A New Method for Predicting Decomposition Temperature of Imidazolium‐based Energetic Ionic Liquids

Two novel correlations are introduced to predict decomposition temperatures of imidazolium‐based energetic ionic liquids. The first simple model is based only on the number of some of atoms in cationic and anionic structures. Meanwhile, a suitable correction term was added in the second correlation to adjust the predicted results for the presence of some specific cation/anion moieties. The measured data of 164 different types of imidazolium‐based energetic ionic liquids were used to derive the new correlations. The calculated mean absolute percent errors (MAPEs) of the first and second models are 6 and 4, respectively. The predicted results have confirmed that insertion of correcting function in the second correlation can provide better estimations. These models were also tested and compared with one of the best available group contribution methods, where group contribution method can be applied, for 17 further imidazolium‐based energetic ionic liquids containing complex molecular structures. Furthermore, the predicted values of MAPEs of the new models are close to that of obtained by group contribution method.     

Hydroxyl-containing imidazolium ionic liquids

A number of imidazolium ionic liquids with bis(trifluoromethylsulfonyl)imide anion containing a ω-hydroxyalkyl substituent of different lengths in the cation (n_С = 2–8) were synthesized. The properties of the obtained liquids were investigated by DSC, TGA, IR, and NMR spectroscopy. Their thermal stability was studied; melting points, viscosity, and volatility in vacuum were measured. The possibility of using synthesized ionic liquids as heat carriers under high vacuum conditions is demonstrated.     

Exploration of 4,5-dimethyl-1H-imidazole N-oxide derivatives in the synthesis of new achiral and chiral ionic liquids

New 1-alkoxy-3-alkyl-4,5-dimethylimidazolium bromides were synthesized by alkylation of the corresponding 1-alkylimidazole 3-oxides, which were conveniently prepared via condensation of α-(hydroxyimino)ketones, primary aliphatic amines, and formaldehyde. By using enantiomerically pure chiral amines, optically active imidazolium salts were obtained. Treatment with sodium tetrafluoroborate in acetone yielded the corresponding imidazolium tetrafluoroborates. All these compounds, with only one exception, were obtained as oils, which are considered as potential ionic liquids and ‘chiral ionic liquids’. The reduction of the chiral or non-chiral 1-alkylimidazole 3-oxides with Raney-Ni, followed by alkylation with alkyl bromides and subsequent ion exchange to tetrafluoroborates, gave the corresponding 1,3-dialkylimidazolium salts, most of them showing properties of ionic liquids. The alkylation of 1-butyl-4,5-dimethylimidazole 3-oxide and the corresponding imidazole, respectively, with 1,3-dibromopropane led to the first bis-imidazolium dibromides and bis-tetrafluoroborates.     

Alkylimidazolium Protic Ionic Liquids: Structural Features and Physicochemical Properties

We focus on a series of protic ionic liquids (PILs) with imidazolium and alkylimidazolium (1R3HIm, R=methyl, ethyl, propyl, and butyl) cations. Using the literature data and our experimental results on the thermal and transport properties, we analyze the effects of the anion nature and the alkyl radical length in the cation structure on the above properties. DFT calculations in gas and solvent phase provide further microscopic insights into the structure and cation-anion binding in these PILs. We show that the higher thermodynamic stability of an ion pair raises the PIL decomposition temperature. The melting points of the salts with the same cation decrease as the hydrocarbon radical in the cation becomes longer, which correlates with the weaker ion-ion interaction inthe ion pairs. A comparative analysis of the protic ILs and corresponding ILs (1R3MeIm) with the same radical (R) in the cation structure and the same anion has been performed. The lower melting points of the ILs with 1R3MeIm cations are assumed to result from the weakening of both the ion-ion interaction and the hydrogen bond.     

Revisiting ether-derivatized imidazolium-based ionic liquids

A series of ether-derivatized imidazolium halides have been prepared and characterized. Contrary to literature reports, they are all crystalline solids and have melting points well above room temperature (50-100 degrees C). Single crystals of the imidazolium salts, obtained in situ by slow cooling from their molten state to room temperature, were analyzed by X-ray crystallography, revealing various anion-cation interactions in the solid state. Exchange of the halides with [Tf(2)N]- yielded room temperature ionic liquids with viscosities that are comparable to related 1-alkyl-3-methylimidazolium ionic liquids. Density functional theory combined with IR spectroscopy has been used to analyze the role of functionalization of the imidazolium side chain on the formation of the molecular and supramolecular structure of the compounds and its possible impact on their physical properties.     

Continuous Synthesis of Peralkylated Imidazoles and their Transformation into Ionic Liquids with Improved (Electro)Chemical Stabilities

A versatile and efficient method to synthesize tetrasubstituted imidazoles via a one‐pot modified Debus–Radziszewski reaction and their subsequent transformation into the corresponding imidazolium ionic liquids is reported. The tetrasubstituted imidazoles were also synthesized by means of a continuous flow process. This straightforward synthetic procedure allows for a fast and selective synthesis of tetrasubstituted imidazoles on a large scale. The completely substituted imidazolium dicyanamide and bis(trifluoromethylsulfonyl)imide salts were obtained via a metathesis reaction of the imidazolium iodide salts. The melting points and viscosities are of the same order of magnitude as for their non‐substituted analogues. In addition to the superior chemical stability of these novel ionic liquids, which allows them to be applied in strong alkaline media, the improved thermal and electrochemical stabilities of these compounds compared with conventional imidazolium ionic liquids is also demonstrated by thermogravimetrical analysis (TGA) and cyclic voltammetry (CV). Although increased substitution of the ionic liquids does not further increase thermal stability, a definite increase in cathodic stability is observable.     

Effect of Hydroxyl Groups in a Cation Structure on the Properties of Ionic Liquids

Two series of imidazolium ionic liquids with the bis(trifluoromethylsulfonyl)imide anion were synthesized, which differ by the presence of a hydroxyl group at the ω-position of the alkyl substituent in the cation structure (n_C = 2–8). The properties of the liquids were studied by DSC, TGA, and IR and NMR spectroscopy. Their thermal stability was studied, and the melting points, viscosity, and volatility in vacuum were measured. The effect of OH groups in the structure of the ionic liquid on its properties was evaluated.