新型磺酸功能化离子液体理化性质的研究

合成了三类磺酸功能化离子液体,通过STA、DSC-TG、UV-Vis、运动粘度/密度计等手段考察了离子液体的热力学性质、酸度、粘度和密度等理化性质,发现离子液体阴阳离子的结构对这些理化性质有不同程度的影响,并对离子液体的结构与理化性质变化关系进行初步探讨.     

Protein Refolding by N-Alkylpyridinium and N-Alkyl-N-methylpyrrolidinium Ionic Liquids

An important property of ionic liquids consisting of cations and anions is that the chemical structures can be easily tuned. To expand the repertoire of effective ionic liquid-based refolding additives, we focused on this tunable property and investigated the effects of new candidates such as N-alkylpyridinium chlorides and N-alkyl-N-methylpyrrolidinium chlorides on protein refolding. Denatured lysozyme (30 mg/mL) was used as a model protein and refolded by 30-fold dilution with various refolding buffers containing different ionic liquids consisting of a systematic variety of alkyl chains. Compared with the refolding yield without additives (lower than 10%), less hydrophobic ionic liquids such as N-ethyl, N-butyl and N-hexylpyridinium chlorides, and N-butyl-N-methylpyrrolidinium chloride were effective in enhancing the refolding yields (46–69%), because they primarily suppressed aggregation because of their chaotropic properties. N-alkylpyridinium cations were more hydrophobic than N-alkyl-N-methylpyrrolidinium cations according to the calculated log P values and prevented aggregation at lower concentrations because of their hydrophobicity. The results provide a range of new effective ionic liquid-based additives for higher protein refolding yields and the knowledge of the effect of chemical structures of additives on protein refolding.     

Hydrogen bonds in imidazolium ionic liquids

It is critically important to understand the structural properties of ionic liquids. In this work, the structures of cations, anions, and cation-anion ion-pairs of 1,3-dialkylimidazolium based ionic liquids were optimized systematically at the B3LYP/6-31+G level of DFT theory, and their most stable geometries were obtained. It was found that there exist only one-hydrogen-bonded ion-pairs in single-atomic anion ionic liquids such as [emim]Cl and [emim]Br, while one- and two-hydrogen-bonded ion-pairs in multiple atomic anion ionic liquids such as [emim]BF(4) and [emim]PF(6) exist. Further studies showed that the cations and anions connect each other to form a hydrogen-bonded network in 1,3-dialkylimidazolium halides, which has been proven by experimental measurement. Furthermore, the correlation of melting points and the interaction energies was discussed for both the single atomic anion and multiple atomic anion ionic liquids.     

The influence of hydrogen bonding on the physical properties of ionic liquids

Potential applications of ionic liquids depend on the properties of this class of liquid material. To a large extent the structure and properties of these Coulomb systems are determined by the intermolecular interactions among anions and cations. In particular the subtle balance between Coulomb forces, hydrogen bonds and dispersion forces is of great importance for the understanding of ionic liquids. The purpose of the present paper is to answer three questions: Do hydrogen bonds exist in these Coulomb fluids? To what extent do hydrogen bonds contribute to the overall interaction between anions and cations? And finally, are hydrogen bonds important for the physical properties of ionic liquids? All these questions are addressed by using a suitable combination of experimental and theoretical methods including newly synthesized imidazolium-based ionic liquids, far infrared spectroscopy, terahertz spectroscopy, DFT calculations, differential scanning calorimetry (DSC), viscometry and quartz-crystal-microbalance measurements. The key statement is that although ionic liquids consist solely of anions and cations and Coulomb forces are the dominating interaction, local and directional interaction such as hydrogen bonding has significant influence on the structure and properties of ionic liquids. This is demonstrated for the case of melting points, viscosities and enthalpies of vaporization. As a consequence, a variety of important properties can be tuned towards a larger working temperature range, finally expanding the range of potential applications.     

Hydrophilic quaternary ammonium type ionic liquids. Systematic study of the relationship among molecular structures, osmotic pressures, and water-solubility

This Letter examines the relationship between the structures of ionic liquids and their water-solubility or osmotic pressure with a number of synthesized quaternary ammonium type ionic liquids and organic salts containing a hydroxyl group as hydrophilic substituted groups on ammonium group cations, and bromide or methylsulfonate as anions. The study found a linear relation between the amount and osmotic pressure of the water-soluble ionic liquids synthesized here, strongly indicating that these water-soluble ionic liquids are perfectly ionized in water like inorganic salts with small diameter ions.     

核磁共振波谱技术在室温离子液体研究中的应用*

室温离子液体作为一种绿色溶剂和功能材料,越来越引起人们的重视,其研究手段也越来越多。本文着重概述了核磁共振方法在测定离子液体的结构、纯度及性质,研究离子液体阴阳离子间的相互作用、离子液体与其他化合物的相互作用、离子液体及其在混合体系中的动力学特征、离子液体在溶液中的聚集行为,以及测定离子液体的热力学参数中的应用。     

离子液体固定化材料在固相萃取中的应用研究进展

离子液体是由阴、阳离子组成的低温熔融盐,几乎没有蒸汽压,具有稳定性好、溶解能力强、结构可设计、导电性好等优良性能。离子液体作为一种广受关注的新型“绿色溶剂”,具有代替传统有机溶剂的潜力,其制备方法和应用范围研究日趋完善和多样,已广泛应用于催化化学、光电化学、材料化学和分析化学等领域。离子液体通过功能化导向设计后,可以将羟基、氨基、羧基、氰基等活性基团键合在离子液体结构上,促使其更加易于与目标分子通过生成π-π键、氢键、离子键和范德华力等而产生相互作用,更加易于发生固定化反应。将离子液体负载到固体载体材料进行固定化后,新型材料既可以减少离子液体的流失,同时保留了离子液体和固体载体的独特性能,具有富集效率高、吸附容量高、稳定性好、识别位点多、萃取选择性强、离子液体利用率高等特点,近年来,在有机小分子固相萃取分离研究中应用广泛。该文从离子液体与硅胶、分子筛、分子印迹聚合物、氧化石墨烯、磁性材料等固体载体的固定化研究情况入手,综述了离子液体固定化材料在固相萃取分离中的应用情况,涉及的目标分离物质包括生物碱类、黄酮类、多酚类等天然活性成分,以及常见药物分子、有机农药等有机小分子化合物,系统地介绍了离子液体与多种载体固定化的性质、应用和分离机制。离子液体的引入,增加了复合材料的活性位点分布和吸附容量,离子液体固定化材料的吸附效率与离子液体种类、吸附材料用量、样品溶液浓度、吸附温度、pH值、洗脱溶剂类型、用量及流速等因素有关。该文探讨了离子液体结构相对单一、相关基础理论研究相对薄弱、复杂基质萃取程度不理想等问题,并提出相应的解决思路,以期为离子液体固定化材料在复杂基质中目标分子分离分析方面的应用提供借鉴和参考。     

烷基磺酸酯基功能化离子液体的合成、性质及其在酯化反应中的应用(英文)

采用廉价易得的原料合成了阳离子含有烷基磺酸酯官能团的功能化离子液体,并考察了其热稳定性.该离子液体可催化羧酸的酯化反应,其催化活性高于阳离子非功能化的离子液体,而与磺酸功能化离子液体相当.同时采用电喷雾电离质谱考察了该离子液体在酯化反应中的作用.     

Carbon dioxide capture by aminoalkyl imidazolium-based ionic liquid: a computational investigation

Efficient technologies/processes for CO(2) capture are greatly desired, and ionic liquids are recognized as promising materials for this purpose. However, the mechanisms for selectively capturing CO(2) by ionic liquids are unclear. In this study, the interactions between CO(2) and 1-n-amino-alkyl-3-methyl-imidazolium tetrafluoroborate, an amino imidazolium ionic liquid (AIIL), in its CO(2) capturing process, are elucidated with both quantum chemistry and molecular dynamics approaches on the molecular level. The effects of the straight aminoalkyl chain length in imidazolium-based cations on CO(2) capture are explored, and thereby the factors governing CO(2) capture for this ionic liquid family, e.g., ionic liquid structure, charge distribution, intermolecular interactions, thermodynamic properties and absorption kinetics, are analyzed. Molecular dynamics simulations are used to study the diffusion of the involved compounds and liquid structures of the CO(2)-AIIL systems. The results show that the amino-alkyl chain length plays an important role in governing the absorption properties of AIILs, including the free energies of absorption, equilibrium constants, desorption temperature, absorption rate constants, diffusion coefficients, and organization of CO(2) around cations and anions. This study provides useful information about rational design of ionic liquids for efficient CO(2) capture.     

Air and water stable ionic liquids in physical chemistry

Ionic liquids are defined today as liquids which solely consist of cations and anions and which by definition must have a melting point of 100 degrees C or below. Originating from electrochemistry in AlCl(3) based liquids an enormous progress was made during the recent 10 years to synthesize ionic liquids that can be handled under ambient conditions, and today about 300 ionic liquids are already commercially available. Whereas the main interest is still focussed on organic and technical chemistry, various aspects of physical chemistry in ionic liquids are discussed now in literature. In this review article we give a short overview on physicochemical aspects of ionic liquids, such as physical properties of ionic liquids, nanoparticles, nanotubes, batteries, spectroscopy, thermodynamics and catalysis of/in ionic liquids. The focus is set on air and water stable ionic liquids as they will presumably dominate various fields of chemistry in future.     

离子色谱法在离子液体阴阳离子分析中的应用

离子液体作为一种新型绿色环保有机化合物,因具有饱和蒸气压低、溶解性良好以及电导率高等优异性质,而在化学化工领域中得到了较为广泛的应用,并越来越受到人们的关注。该文综述了近年来离子色谱在离子液体阴阳离子分析中的应用,对离子色谱法分析离子液体阳离子、离子液体阴离子以及同时分析离子液体阴阳离子三方面进行讨论,并对离子色谱法分析离子液体的发展趋势进行了展望。     

功能化离子液体的制备及其在合成中的应用

功能化离子液体;手性离子液体;酸性离子液体     

Paramagnetic surface active ionic liquids: synthesis,properties, and applications

Paramagnetic surface active ionic liquids (PMSAILs) classify task-specific ionic liquids with magnetic properties by incorporating metal into the cationic or anionic part of the ionic liquid. Paramagnetic ionic liquids had long-chain either in cations or anions and showed excellent surface activity and magnetic properties without any need for the magnetic nanoparticles. These PMSAILs have inherent unique ionic liquid properties and self-assembled into various nano-aggregates such as micelles, vesicles, rod-like micelles, and etc., by modification in the structure of cations or anions. PMSAILs provide stimuli-responsive properties, which is one of the essential aspects of targeted applications. The appropriate functional tunability of anions and cations in PMSAILs leads to various multifaceted chemical and biological applications. A new emerging trend in PMSAIL research is hybridization with flexible materials. This review will mainly deal with the synthesis, characterization, and brief history of PMSAILs and their potential advantages in the various applications in micellar catalysis, purification and separation of biomolecules, compaction and decompaction of DNA, drug delivery, and other biomedical applications.     

Structure and conformation properties of 1-alkyl-3-methylimidazolium halide ionic liquids: a density-functional theory study

The structures and conformational properties of 1-alkyl-3-methylimidazolium halide ionic liquids have been studied with a Becke's 3 Parameter functional method. The interaction mechanisms between the cation and the anion in 1-ethyl-3-methylimidazolium (Emim+) halide and 1-butyl-3-methylimidazolium (Bmim+) halide ionic liquids were investigated using 6-31G*, 6-31++G**, and 6-311++G** basis sets. Forty structures of different ion pairs were optimized and geometrical parameters of them have been discussed in details. Halide ions (Cl- or Br-) have been gradually placed in different regions around imidazolium cation and the interaction energies between the anion and the cation have been calculated. Theoretical results indicate that there are four activity regions in the vicinity of the imidazolium cations, in these regions the imidazolium cations and the halide anions formed stable ion pairs. Imidazolium cations can form hydrogen bond interactions with one, two or three but no more than three nearest halide anions. The halide ions are situated in hydrogen bond positions rather than at random.     

Effect of stationary phase polarity on the retention of ionic liquid cations in reversed phase liquid chromatography

Chromatographic analysis of ionic liquids on different types of packings offers interesting possibility to determine their retention mechanism. As a consequence, the major interactions between stationary phase ligands and analyzed chemical entities can be defined. The main aim of this work was to analyze cations of ionic liquids on chemically bonded stationary phases with specific structural properties. The attempt to predict the main interactions between positive ions of ionic liquids and stationary phase ligands was undertaken. For that purpose, butyl, octyl, octadecyl, phenyl, aryl, mixed, alkylamide, and cholesterolic packings were chosen and applied to the analysis of six most commonly used ionic liquids' cations. Obtained results indicate mainly dispersive and pi-pi type of interaction part in the retention mechanism of analyzed compounds.     

Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids

Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented.     

Application of ionic liquids containing tricyanomethanide [C(CN)3]- or tetracyanoborate [B(CN)4]- anions in dye-sensitized solar cells

A series of novel ionic liquids composed of imidazolium, pyridinium, pyrrolidinium, and ammonium cations with tricyanomethanide or tetracyanoborate anions were prepared. The ionic liquids were characterized by NMR and IR spectroscopy and ESI-mass spectrometry, and their physical properties were investigated. Solid state structures of the N-propyl-N-methylpyrrolidinium and triethylpropylammonium tetracyanoborate salts were obtained by single crystal X-ray diffraction. The salts that are liquid at room temperature were evaluated as electrolyte additives in dye-sensitized solar cells, giving rise to efficiencies 7.35 and 7.85% under 100 and 10% Sun, respectively, in combination with the standard Z907 dye.     

Molecular dynamics simulations of the structure and transport properties of tetra-butylphosphonium amino acid ionic liquids

Systematic molecular dynamics simulations are used to study the structure, dynamics and transport properties of the ionic liquids composed of the tetra-butylphosphonium ([TBP](+), or [P(C(4)H(9))(4)](+)) cation with six amino acid ([AA](-)) anions. The structural features of these ionic liquids were characterized by calculating the partial site-site radial distribution functions, g(r), and computing the dihedral angle distribution of n-butyl side chains in the [TBP](+) cations. The dynamics of the ionic liquids are described by studying the velocity autocorrelation function (VACF) and the mean-square displacement (MSD) for the centers of mass of the ions at different temperatures. The ionic diffusion coefficients and the electrical conductivities were evaluated from both the Einstein and Green-Kubo methods. The cross-correlation terms in the electric-current autocorrelation functions, which are an indication of the ion pair correlations, are investigated. The cationic transference numbers were also estimated to study the contributions of the anions and cations to the transport of charge in these ionic liquids. We determined the role of the amino acid anion structures on the dynamical behavior and the transport coefficients of this family of ionic liquids. In general, the MSD and self-diffusion coefficients of the relatively heavier non-planar [TBP](+) cations are smaller than those of the lighter amino acid anions. Introducing polar functional groups (acid or amide) in the side chain of [AA](-) decreases the diffusion coefficient and electrical conductivity of AAILs. The major factors for determining the magnitude of the transport coefficients are the chemical functionality and the length of the alkyl side chain of the [AA](-) anion of these [TBP][AA] ionic liquids.     

Review of ionic liquids with fluorine-containing anions

Interest in ionic liquids has grown markedly in recent years. The syntheses, characterization and properties of quaternary alkyl-substituted ammonium, imidazolium, triazolium and pyridinium salts with a variety of fluorine-containing anions have been studied in detail; however, ionic liquids with other cations and anions continue to be discovered. This review is limited to the literature from 2000 to 2005 dealing with ionic liquids with fluorine-containing anions.