Ionic Liquids with Weakly Coordinating [M(III)(OR(F))4](-) Anions.
Ionic Liquids with Weakly Coordinating [M(III)(OR(F))4](-) Anions.
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DOI：
10.1021/acs.accounts.5b00247
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发表时间：
2015-08
影响因子：
18.3
通讯作者：
Alexander B. A. Rupp;I. Krossing
中科院分区：
文献类型：
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作者：
Alexander B. A. Rupp;I. Krossing
离子液体被定义为熔点低于100°C的盐。在过去的二十年中，由于其独特的性能，包括高导电性、低粘度、可忽略的蒸气压和高电化学电阻，它们引起了广泛的关注。ILs被视为可调系统，其中（也在混合物中）可能存在多达10（19）种组合。这些特性使ILs成为各种基础工业应用的有趣候选者。我们在这一领域的补充是弱配位，相互作用小的阴离子，高氟铝酸盐[Al(OR(F))4](-) (R(F) = C(CF3)3， C(CH3), (CF3)2和CH（CF3)2，后来还有CH2(CF3)）。我们已经在广泛的应用中使用了这些阴离子，包括活性阳离子的稳定，（聚合）催化，以及循环伏安法或电化学电池中的导电盐。特别是[Al(Ohfip)4](-) （hfip = CH(CF3)2）阴离子与不对称有机阳离子结合，非常适合合成熔点极低的il，有些甚至远低于0°C。类似的硼酸盐[B(OR(F))4]（-）也被证明可以生成il，目前已经合成了大量的铝酸盐和硼酸盐il并对其进行了深入的研究。在许多方面，至少[Al(Ohfip)4](-) il呈现出几乎理想的非相互作用原型il，具有（几乎）各向同性但弱且平坦的库仑势。因此，与其他种类的离子间相互作用相比，它们的整体离子间相互作用显著减少，导致极低程度的离子配对，或者（对于短阳离子链长度低于6的离子链）甚至完全没有离子配对。通过对控制这类具有最小相互作用的高度氟化IL的物理性质的原理的彻底分析，我们能够学习到可以扩展的基本原理，例如，用于预测各种典型IL的主要性质。在这篇文章中，我们对它们的合成、热学和毒理学行为、物理和动态性能以及在电化学中的应用进行了全面的综述。我们描述了我们实验室开发的[M(III)(OR(F))4](-) il的优点和局限性，并对这些领域的知识仍然缺乏进行了展望。
Ionic liquids (ILs) are defined as salts with melting points below 100 °C. They attracted much attention in the last two decades due to their unique set of properties, including high conductivities, low viscosities, negligible vapor pressure, and high electrochemical resistance. ILs are seen as tunable systems, of which (also in mixtures) up to 10(19) combinations may exist. These properties make ILs interesting candidates for a variety of fundamental to industrial applications. Our addition to this field was weakly coordinating, little interacting anions, the highly fluorinated aluminates [Al(OR(F))4](-) (R(F) = C(CF3)3, C(CH3), (CF3)2, and CH(CF3)2 and later also CH2(CF3)). We have used these anions in a broad spectrum of applications, including the stabilization of reactive cations, (polymerization) catalysis, and conducting salts for cyclic voltammetry or in electrochemical cells. Especially the [Al(Ohfip)4](-) (hfip = CH(CF3)2) anions in combination with asymmetric organic cations turned out to be very well suited for the synthesis of ILs with very low melting points, some even far below 0 °C. Also the analogous borates, [B(OR(F))4](-), were shown to yield ILs, and currently a plethora of such aluminate and borate ILs have been synthesized and thoroughly investigated. In many aspects, at least the [Al(Ohfip)4](-) ILs present almost ideally noninteracting prototype ILs with (nearly) isotropic but weak and flat Coulomb potential. Consequently, their overall interionic interactions are significantly reduced compared with other classes of ILs, resulting in an extraordinarily low degree, or (for short cation chain lengths below six) even complete absence of ion pairing. From thorough analysis of the principles governing the physical properties of this highly fluorinated IL class with minimized interactions, we were able to learn basic principles that could be extended, for example, to the prediction of the principal properties of a wide variety of typical ILs. In this Account, we give a comprehensive review of their syntheses, thermal and toxicological behavior, physical as well as dynamic properties, and use in electrochemical applications. We delineate advantages and limitations of the [M(III)(OR(F))4](-) ILs developed in our lab and give an outlook on those fields, in which there is still a lack of knowledge.