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Time-resolved fluorescence spectra and fluorescence anisotropy decay of 2-aminoquinoline (2AQ) have been measured in eight room-temperature ionic liquids, including five imidazolium-based aromatic ionic liquids and three nonaromatic ionic liquids. The same experiments have also been carried out in several ordinary molecular liquids for comparison. The observed time-resolved fluorescence spectra indicate the formation of pi-pi aromatic complexes of 2AQ in some of the aromatic ionic liquids but not in the nonaromatic ionic liquids. The fluorescence anisotropy decay data show unusually slow rotational diffusion of 2AQ in the aromatic ionic liquids, suggesting the formation of solute-solvent complexes. The probe 2AQ molecule is likely to be incorporated in the possible local structure of ionic liquids, and hence the anisotropy decays only through the rotation of the whole local structure, making the apparent rotational diffusion of 2AQ slow. The rotational diffusion time decreases rapidly by adding a small amount of acetonitrile to the solution. This observation is interpreted in terms of the local structure formation in the aromatic ionic liquids and its destruction by acetonitrile. No unusual behavior upon addition of acetonitrile has been found for the nonaromatic ionic liquids. It is argued that the aromaticity of the imidazolium cation plays a key role in the local structure formation in imidazolium-based ionic liquids. 相似文献
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Temperature dependent molar conductances and fluidities of bisulfate and ethyl sulfate anion-based ionic liquids were measured. The extent of dissociation of the ionic liquids was estimated from the Walden plot in term of ionicity. The ionicity mainly depends on the magnitude of Coulombic forces, altered by the anion’s Lewis basicity. Aqueous solutions of aprotic ionic liquids, in general, possesses ionicity in the range of ≈70–99%. This article reveals that the substitution of the anion by bisulfate and ethylsulfate reduces the ionicity of aqueous solution of these ionic liquids to the range of 10–37%. This is very close to that exhibited by some of the protic ionic liquids and phosphonium based ionic liquids with sweetner anions. The concentration dependent molar conductance of these ionic liquids has been fitted to Mahiuddin and Ismail’s equation. To our surprise, the molar conductances of bisulfate-based aprotic ionic liquids are remarkably high, even though these ionic liquids possess lower ionicity. 相似文献
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Assoc. Prof. Dr. Akihito Imanishi 《Chemical record (New York, N.Y.)》2023,23(8):e202300110
Ionic liquids (ILs) have attracted much attention as tunable liquids because of their unique structures and properties. However, the mechanisms of chemical reactions and solute diffusion in ionic liquids are still unknown. This article summarizes our previous studies and recent results on the mechanisms of metal particle formation and solute diffusion in ionic liquids, focusing on the local structure of ionic liquids. It was found that the shape and size of metal particles formed in ionic liquids using electron beams or X-rays are strongly influenced by the local structure. In the study of the diffusion behavior of metal ions in ionic liquids, we proposed a hopping-like diffusion model and proposed that this behavior could be strongly influenced by local structures such as hole concentration and/or domain structures. 相似文献
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二苯醚烷基化反应中酸性离子液体的循环使用 总被引:3,自引:0,他引:3
使用酸性离子液体催化二苯醚与十二烯烷基化反应,考察了离子液体的失活原因,提出了循环使用离子液体的解决办法.在二苯醚与十二烯烷基化反应中, Lewis酸性离子液体不能多次循环使用的原因是离子液体与二苯醚相互作用导致具有催化活性的Al2Cl72-分解、流失.改变离子液体的阳离子不能从本质上解决其与二苯醚间的相互作用.适时补加损失量的AlCl3使离子液体的Lewis酸性得以恢复,可以解决体系中酸性离子液体循环使用问题,循环使用8次后产物产率仍保持90%左右. 相似文献
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Young's modulus and mechanical damping of 15 organic liquids in polystyrene have been measured from 4°K to 250°K. The concentration was generally in the range from 10 to 15%, but the polystyrene–toluene system was investigated over the range from 0 to 16%. Some liquids cause the 40°K damping peak of polystyrene to disappear, other liquids do not. Seven of the liquids which cause the disappearance of the 40°K peak give rise to new large damping peaks at the temperature expected for the secondary glass transition temperatures of the liquids, that is, at 0.77 Tg of the liquids. Some of the liquids produced large unexplained damping peaks at temperatures above the expected glass transition temperatures Tg of the liquids. It is suggested that the γ peak in polystyrene is caused by styrene monomer. 相似文献
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Ionic liquids are a class of solvents widely studied in the literature for various applications. As a subclass of ionic liquids, redox ionic liquids can endow charge exchange properties (electrons transfer) to these electrolytes for electrochemical energy storage. In this review article, we propose to study this family of ionic liquids and suggest a chronological classification. We introduce five generations of redox ionic liquids with different basic compounds such as polyethylene glycol, ferrocene, different linker lengths, TFSI anion, and biredox ionic liquids. The versatility of the redox ionic liquids synthesis will be discussed as well as the fundamental and applied aspects of their use as electrolytes, which have high charge densities. The impact of the redox ionic liquids on the electrochemical mechanisms will be described. We also present how the redox shuttle effect, detrimental to supercapacitors, can be prevented while it can be used to improve lithium-ion batteries. 相似文献
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二茂铁在几种离子液体中的迁移行为 总被引:3,自引:1,他引:2
采用循环伏安法研究了二茂铁(Fc)在几种离子液体中的迁移行为. 计算了Fc在各离子液体中的扩散系数和粘度系数,探讨了离子液体粘度与离子液体结构之间的关系. 实验结果表明, 离子液体的粘度随阳离子取代基碳链长度的增加而增加, 随阴离子对称性的增加而增加. 相似文献
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Synthesis of Multiester-appended and Multicarboxylic-appended Imidazolium Ionic Liquids 总被引:2,自引:0,他引:2
Wei Guo GENG Xuc Hui LI Le Fu WANG Hong Li DUAN Wei Ping PAN 《中国化学快报》2006,17(2):169-172
Currently ionic liquids (ILs) are attracting considerable interest as eco-friendly solventsfor the replacement of volatile organic solvents in organic synthesis and catalysis1.Low-melting ILs based on imidazolium cations have dominated this area over the … 相似文献
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Zabet-Moghaddam M Krüger R Heinzle E Tholey A 《Journal of mass spectrometry : JMS》2004,39(12):1494-1505
Ionic liquids are interesting solvents for a number of applications in chemistry and biotechnology. We characterized five different ionic liquids by laser desorption/ionization (LDI) and by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and studied the analysis of amino acids, peptides and proteins dissolved in these solvents. Signals of both anions and cations of the ionic liquids could be observed both in LDI- and in MALDI-MS. In the latter case, adduct formation between anions and cations of the analytes was observed. Amino acids, peptides and proteins could be analyzed in ionic liquids after addition of matrix substances. Sodium and potassium adducts were not observed in any analysis involving ionic liquids. Low molecular mass compounds and peptides could be analyzed best in the presence of water-immiscible ionic liquids, whereas proteins gave the best results in water-miscible ionic liquids. Optimal analysis conditions such as molar matrix-to-analyte and ionic liquid-to-matrix ratios were determined. Homogeneity of samples in the presence of ionic liquids was reduced compared with classical MALDI preparations. Relative quantitation of amino acids was possible using isotope-labeled internal standards. MALDI-MS thus can be used for the analysis of chemical reactions and the screening of enzyme-catalyzed reactions in ionic liquids and for the analysis of the biocatalysts dissolved in these solvents. Theoretical aspects of ion formation in the presence of ionic liquids both in LDI and MALDI analysis are discussed. 相似文献
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The sonication of ionic organic liquids leads to decomposition of the liquids. Multibubble sonoluminescence spectra and headgas analysis reveal a variety of decomposition products from the sonolysis of N,N'-dialkylimidazolium ionic liquids. The decomposition is a result of acoustic cavitation, which generates localized hot spots from the implosive collapse of bubbles in the ionic liquids. Despite the negligible vapor pressure of the ionic liquids, reaction still occurs in a heated shell of the bubbles or from microdroplets thrown into the collapsing bubbles. 相似文献
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《Journal of separation science》2018,41(1):373-384
Ionic liquids have been functionalized for modern applications. The functional ionic liquids are also called task‐specific ionic liquids. Various task‐specific ionic liquids with certain groups have been constructed and exploited widely in the field of separation. To take advantage of their properties in separation science, task‐specific ionic liquids are generally used in techniques such as liquid–liquid extraction, solid‐phase extraction, gas chromatography, high‐performance liquid chromatography, and capillary electrophoresis. This review mainly covers original research papers published in the last five years, and we will focus on task‐specific ionic liquids as the chiral selectors in chiral resolution and as extractant or sensor for biological samples and metal ion purification. 相似文献
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Within the last decade, ionic liquids have come to the fore as environmentally-responsible designer solvents. But what are ionic liquids and what can they offer the analytical scientist? This article addresses these questions and chronicles recent progress made in the application of ionic liquids toward analytical problem-solving. While further progress is required before ionic liquids become mainstream analytical solvents, results to date commend their use in various modes of chemical analysis. It is our aim that the findings reported herein draw other researchers into this area and encourage the increased application of ionic liquids in this manner. 相似文献