芳烃与烯烃烷基化反应的催化机理进展

芳烃与烯烃的反应在有机合成中应用广泛。随着环保要求的提高,用于芳烃烷基化反应的传统催化剂逐渐被新型绿色催化剂所替代。近年来研究发现离子液体和分子筛对该反应具有高效催化作用且环境友好。本文探讨了离子液体和分子筛的酸性,总结了相应的的催化机理,对有关实验和理论研究工作进行了分析。同时揭示了离子液体和分子筛的结构对其催化性能的影响,为烷基化反应进一步研究奠定了基础。分析表明离子液体既能作为B酸,也能作为L酸起催化作用;分子筛主要作为B酸起催化作用,同时其催化性能与孔道结构、孔径大小及反应物尺寸密切相关。离子液体的稳定性较差、成本较高,而分子筛失活较快,未来需围绕提高离子液体稳定性、改进其制备方法以降低成本及改善分子筛结构以延长使用周期等方面展开研究。     

Structure and solvation in ionic liquids

This Account describes experimental data used to understand the structure of ionic liquids and solute-solvent interactions of both molecular solutes and dissolved metal complexes. In general, the structures of the ionic liquids determined from experimental data show good agreement with both simulated structures and solid-state structures. For all ionic liquids studied, strong charge ordering is found leading to long-range order even in the presence of a solute. For dissolved metal complexes, the ionic liquid is not innocent and a clear dependence on the speciation is observed with variations in both the cation and anion.     

低维纳米受限离子液体的研究进展

离子液体受限于低维纳米空间时,分子热运动会受到极大限制,导致其结构和性质与三维体相离子液体相比具有显著差异。电场、磁场和温度等外部条件及限域通道的尺寸、表面物化性质和几何形貌等因素会极大地影响低维纳米受限离子液体的微观结构与物化性质。本综述围绕低维纳米受限离子液体的最新研究进展,介绍了常用的实验和理论方法,总结了低维纳米受限离子液体结构和氢键网络的动态调控机理,讨论了不同低维纳米受限离子液体体系的热力学性质、物化性质和结构相变等特性,梳理了低维纳米受限离子液体体系在气体分离、限域催化和超级电容器储能等方面的应用,最后展望了低维纳米受限离子液体未来的前景与挑战。     

Ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride in ionic liquids

This work deals with ring-opening polymerization of a representative N-carboxy-α-amino acid anhydride (NCA) in ionic liquids. The polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride (BLG-NCA) with n-butylamine as an initiator in an ionic liquid ([BMI][PF₆]) proceeded as a milky white dispersion with no evidence of macroscopic precipitation. The polymerization with the primary amine under suitable conditions afforded poly(amino acid) having narrow polydispersity, molecular weights close to the theoretical values, and helical secondary structure. The polymerization rate was slightly affected by the nature of the anion and hydrophobicity of the ionic liquids, while poly(BLG)s having low polydispersities were obtained regardless of the kind of the ionic liquids. Several parameters, such as the existence of organic solvent as a co-solvent and monomer concentration, had also clear effects on the polymerization rate and/or the polydispersity of the resulting poly(BLG)s. The possible interactions between the ionic liquid and NCA monomer or the ionic liquid and the initiator were characterized using FT-IR, ¹H and ¹³C NMR measurements. The character of this polymerization process was also studied by performing kinetic investigations. We believe that this represents the first report on amine-initiated ring-opening polymerization of NCA in ionic liquid.     

Charge transport and glassy dynamics in ionic liquids

Ionic liquids (ILs) exhibit unique features such as low melting points, low vapor pressures, wide liquidus temperature ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. As a result, they show promise for use in variety of applications: as reaction media, in batteries and supercapacitors, in solar and fuel cells, for electrochemical deposition of metals and semiconductors, for protein extraction and crystallization, and many others. Because of the ease with which they can be supercooled, ionic liquids offer new opportunities to investigate long-standing questions regarding the nature of the dynamic glass transition and its possible link to charge transport. Despite the significant steps achieved from experimental and theoretical studies, no generally accepted quantitative theory of dynamic glass transition to date has been capable of reproducing all the experimentally observed features. In this Account, we discuss recent studies of the interplay between charge transport and glassy dynamics in ionic liquids as investigated by a combination of several experimental techniques including broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance, dynamic mechanical spectroscopy, and differential scanning calorimetry. Based on Einstein-Smoluchowski relations, we use dielectric spectra of ionic liquids to determine diffusion coefficients in quantitative agreement with independent pulsed field gradient nuclear magnetic resonance measurements, but spanning a broader range of more than 10 orders of magnitude. This approach provides a novel opportunity to determine the electrical mobility and effective number density of charge carriers as well as their types of thermal activation from the measured dc conductivity separately. We also unravel the origin of the remarkable universality of charge transport in different classes of glass-forming ionic liquids.     

咪唑型离子液体在有序分子组合体中的应用

离子液体符合绿色化学发展的需要,对其研究是近年来科研工作者密切关注的课题。介绍了咪唑型离子液体在囊泡、液晶、胶束、微乳液等分子有序组合体中的应用研究。     

Integration or segregation: how do molecules behave at oil/water interfaces?

It has been over 250 years since Benjamin Franklin, fascinated with the wave-stilling effect of oil on water, performed his famous oil-drop experiments; nevertheless, the behavior of water molecules adjacent to hydrophobic surfaces continues to fascinate today. In the 18th century, the calming of the seas seemed the most pertinent application of such knowledge; today, we understand that oil-on-water phenomena underlie a range of important chemical, physical, and biological processes, including micelle and membrane formation, protein folding, chemical separation, oil extraction, nanoparticle formation, and interfacial polymerization. Beyond classical experiments of the oil-water interface, recent interest has focused on deriving a molecular-level picture of this interface or, more generally, of water molecules positioned next to any hydrophobic surface. This Account summarizes more than a decade's work from our laboratories aimed at understanding the nature of the hydrogen bonding occurring between water and a series of organic liquids in contact. Although the common perception is that water molecules and oil molecules positioned at the interface between the immiscible liquids want nothing to do with one another, we have found that weak interactions between these hydrophilic and hydrophobic molecules lead to interesting interfacial behavior, including highly oriented water molecules and layering of the organic medium that extends several molecular layers deep into the bulk organic liquid. For some organic liquids, penetration of oriented water into the organic layer is also apparent, facilitated by molecular interactions established at the molecularly thin region of first contact between the two liquids. The studies involve a combined experimental and computational approach. The primary experimental tool that we have used is vibrational sum frequency spectroscopy (VSFS), a powerful surface-specific vibrational spectroscopic method for measuring the molecular structures of aqueous surfaces. We have compared the results of these spectroscopic studies with our calculated VSF spectra derived from population densities and orientational distributions determined through molecular dynamics (MD) simulations. This combination of experiment and theory provides a powerful opportunity to advance our understanding of molecular processes at aqueous interfaces while also allowing us to test the validity of various molecular models commonly used to describe molecular structure and interactions at such interfaces.     

A molecular approach to bioseparations: Protein-protein and protein-salt interactions

Many bioprocess separations involve manipulating the solution conditions to selectively remove or concentrate a target protein. The selectivity is determined by the thermodynamics of the protein solution, which are governed, at the molecular level, by protein-protein interactions. Thus, to optimise these processes, one must understand the precise nature of these interactions, how they are affected by the control parameters (e.g., temperature, ionic strength, pH), and how they relate to the solution properties of interest (e.g., protein solubility, protein stability, crystal nucleation rates). Recently, studies of protein-protein interactions have been motivated by the discovery of a crystallisation window, which places bounds on the protein-protein attraction that is required for crystallisation to be possible. This review focuses on experimental and theoretical studies of protein-protein interactions and discusses the current gaps in understanding these forces. The first models for these interactions had been based on DLVO theory, which has proven useful for understanding protein-protein interactions in dilute electrolyte solutions. However, DLVO theory does not include such important effects as anisotropic interactions, solvation forces, and specific ion effects. Various approaches have been developed to include these phenomena although they are still not well understood. One outstanding issue concerns specific ion effects, which play a crucial role in biological systems. An initial step in understanding these effects might be to first rationalize protein-salt interactions.     

离子液体在生物质溶解分离中的应用与机理研究

生物质是自然界中最丰富的可再生资源之一,将生物质转化为高附加值化工产品首先要进行生物质预处理,即利用物理、化学和生物等手段削弱细胞壁分子之间的作用,使生物质更容易降解。离子液体具有诸多优异的物理和化学性质,在众多领域引起了广泛关注,近年来在生物质预处理过程中同样展现出良好的效果。综述了近年来离子液体作为木质纤维素溶剂的主要研究成果,重点介绍了溶解机理方面相关研究。介绍了阴阳离子种类及氢键的影响,总结了木质纤维素与离子液体在分子水平上的相互作用机制,最后探讨了离子液体溶解生物质方面的发展前景。     

离子液体的非常规制备技术研究进展

离子液体的大规模应用有赖于其制备技术的不断进步。然而,常规制备方法反应时间长、产品纯化繁琐、不宜规模化等问题,制约着离子液体的工业化应用进程。针对离子液体制备过程的关键环节,综述了目前离子液体非常规制备技术的研究进展,重点介绍了微波、超声波、微波-超声、微反应和STT过程强化制备离子液体的技术研究现状,指出现阶段虽然非常规制备技术取得了重要进展,但是仍然需要通过深入细致的研究,建立完善的理论指导体系,同时还要加快功能化离子液体和绿色化制备技术开发。     

离子液体在化工分离过程中的应用进展

综述了作为优良的绿色分离溶剂,有望替代传统的易挥发有机溶剂的离子液体在化工分离过程中的应用进展,包括生物制品、金属离子、芳香族化合物、燃油中的硫氮化合物的萃取分离,烟气脱硫、气体分离等吸收过程中的应用,简述了离子液体相平衡方面的基础研究进展.     

Thermodynamic Modeling of Imidazolium-Based Ionic Liquids with the [PF6]− Anion for Separation Purposes

There is an increased interest in developing accurate tools to relate the physicochemical properties of ionic liquids (ILs) to their microscopic structure as this information is needed to speed up the design of new ionic liquids for chemical and industrial processes. Molecular models can be used for this purpose. We explore here the extended capabilities of a model previously developed in the context of soft-SAFT, by Andreu and Vega in 2007 to reproduce the thermodynamic behavior of imidazolium hexafluorophosphate-based ([C_nmim][PF₆]) ionic liquids. The molecular parameters optimized in the previous work have been used here in a transferable manner; some new members of the [C_nmim][PF₆] family have also been added, as new recent experimental data has been published. The interfacial tensions have been calculated using a Density Gradient Approach and the results have been compared with available experimental data. The solubility of carbon monoxide and hydrogen in those ILs has been studied in the range of temperatures and pressures of application for separation processes. Binary mixtures with other imidazolium ionic liquids with different anions have been calculated, in a predictive manner. Finally, calculations of mixtures of ionic liquids with water also show very good agreement with experimental data. This work highlights the importance of using a simple but robust thermodynamic model, including the right level of interactions, to accurately describe the properties of these highly non-ideal systems.     

胰岛素活性结构在水合离子液体中的稳定性

离子液体以其独特的、可修饰的分子结构以及优良的物理化学性质被应用于蛋白质的稳定性研究。采用分子动力学模拟方法及微量热法,研究热敏性蛋白药物胰岛素在不同水质量分数下水合离子液体中活性结构的稳定性,并深入分析离子液体与胰岛素之间的相互作用及水分子与蛋白质稳定性之间的关系。研究结果表明,当水质量分数低于25.00%时,胰岛蛋白的热变性温度能保持在68℃以上。且通过模拟分析得出,含水量25.00%的水合离子液体体系中,大量阴、阳离子在胰岛蛋白表面聚集,并通过较强的静电相互作用吸附在其表面,从而对蛋白质的活性结构展现出良好的稳定效果。结合宏观实验研究及微观动力学计算阐释了不同水含量的离子液体稳定蛋白质的作用机理,并为离子液体对蛋白质的稳定作用研究提供了一种新的分析方法。     

铁基离子液的水相合成工艺

目前铁基离子液在基础和应用研究方面得到广泛的关注。从合成铁基离子液的原料出发,通过调节不同原料配比,系统研究了在空气气氛和水环境条件下铁基离子液的合成过程及现象。探索了水相废液再循环使用合成铁基离子液的绿色零排放工艺,对比了无水和水相两种不同环境下产物铁基离子液的差异,以及可能的相互转化条件,为理解和推动铁基离子液的相关研究与应用提供基础参考。     

MECHANICALLY INDUCED STIMULATION OF ELECTROMAGNETIC RADIATION—A NEW ELECTROKINETIC PHENOMENON

It is shown that there must be six. not just four electrokinetic phenomena involving the ionic double layers on solids making contact with liquids. In one of these, the emission of electromagnetic waves from mechanically stimulated colloid systems should be observable. This prediction is based upon the fact that suspended particles in polar liquids normally bear an ionic double layer of charge. The outer liquid-borne portion is readily distortable. Cyclic distortion of it will produce a radiating dipole. Preliminary experimental results show silica gel and yeast (Saccharomyces cerevisiae) suspensions to produce such electromagnetic radiation. The electromagnetic noise in the natural motions of sea and fresh waters may be due in part to this phenomenon.     

离子液体/低共熔溶剂在煤基液体分离中的应用

为了实现煤基液体各组分利用价值最大化,本文综述了离子液体和低共熔溶剂对组分组成复杂的煤基液体进行高效萃取分离的研究进展。首先介绍了离子液体和低共熔溶剂的性质及分类;其次根据分离目标的不同,将离子液体和低共熔溶剂对煤基液体典型组分的萃取分离分为四个方面进行阐述:煤基液体提酚、燃料油萃取脱硫、燃料油萃取脱氮、芳烃和脂肪烃的分离。分析表明,离子液体和低共熔溶剂对实际煤基液体的提酚效果较好,能分离出绝大多数的酚类化合物;燃料油萃取脱硫时,离子液体和低共熔溶剂对实际煤基液体的单次脱硫率均不高,需3～5次重复萃取后才能获得理想效果;燃料油中的碱性及非碱性含氮化合物很难被同一种离子液体或低共熔溶剂一次性分离出,导致实际油品的脱氮率较低;大多数离子液体和低共熔溶剂进行芳烃和脂肪烃的分离时不能获得理想的分配系数和选择性,尚无法用于实际芳烃和脂肪烃的分离。氢键、π-π、CH-π、范德华力等分子间相互作用的差异是实现离子液体或低共熔溶剂进行煤基液体典型组分分离的主要原因。依据分离对象,设计合适的离子液体和低共熔溶剂,提高实际煤基液体分离时的萃取率和选择性;分析并解决离子液体和低共熔溶剂用于实际煤基液体各组分...     

离子液体中电沉积活泼金属的研究进展

离子液体具有宽的电化学窗口、优良的导电性、高的热稳定性、可回收等优点,在绿色冶金电化学方面具有很大的应用潜力和广阔的应用前景.本文介绍了离子液体在活泼金属沉积中应用的研究现状,重点对锂、钠、镁等活泼金属在离子液体中的电化学行为及电沉积进行了阐述,提出了离子液体在金属电沉积应用中存在的一些问题及解决办法,并展望了未来的发...     

新型离子液体的合成及其阳离子基团缓蚀性能

以高纯环烷酸为原料,合成了一系列含咪唑啉环的新型离子液体Ⅰ～Ⅴ,探讨了阳离子咪唑啉基团中N_（3）原子上取代基与缓蚀性能的关系.采用碳钢挂片失重法和电化学测试法,评价了它们在酸性溶液中的缓蚀性能;采用量子化学法和极化效应指数法,分别计算了离子液体Ⅰ～Ⅴ阳离子咪唑啉基团的前线轨道能量及其相应的PEI等参数.实验结果和理论分析表明：离子液体Ⅰ～Ⅴ阳离子咪唑啉基团的缓蚀效率呈现如下关系,Ⅴ＞Ⅳ＞Ⅲ＞Ⅱ＞Ⅰ;其缓蚀效率与E_HOMO、ΔE_L-H和PEI等参数间均具有良好的线性关系.     

Intermolecular dynamics, interactions, and solvation in ionic liquids

Ionic liquids can simultaneously assume multiple solvent roles, because they are strongly polar and polarizable solvents and binary solutions and frequently contain very hydrophobic components. When the cation and anion functional groups are tuned appropriately, ionic liquids can be used as designer solvents for a broad range of applications. In this Account, we discuss our spectroscopic studies on the intermolecular interactions, dynamics, solvation, transport, and friction in ionic liquids, as compared with information obtained from macroscopic experiments including viscometry and calorimetry.     

离子液体中胰岛素结构稳定性的分子动力学模拟

离子液体作为一种新型绿色溶剂,由于其独特的物理化学性质,被广泛应用于蛋白质的稳定性研究。选用热敏性蛋白药物胰岛素作为研究对象,采用分子动力学模拟方法,从分子层面上研究不同种类的离子液体对胰岛素结构的稳定效果。结果表明,与纯水体系相比,在常温下离子液体能够有效地稳定胰岛素的分子结构,且体系中阴离子的氢键碱性越弱,阳离子的烷基链越短,对胰岛素分子结构的稳定作用越强。并深入分析不同烷基链长度的二氰胺类离子液体与胰岛素之间的相互作用,发现相较于长烷基链离子液体,短烷基链离子液体与胰岛素之间的相互作用更强,揭示了后者能更好地维持和稳定胰岛蛋白的分子结构。