Ionic liquids (ILs) are an important class of media that are usually used in combination with polar solvents to reduce costs and tune their physicochemical properties. In this regard, it is essential to understand the influence of adding solvents on the properties of ILs. In this work, the micro-heterogeneity and H-bonding interactions between a hydroxyl-functionalized IL, [HOEmim][TFSI], and acetonitrile (ACN) were investigated by attenuated total reflection Fourier transform infrared spectroscopy and molecular simulations. All studied IL-ACN mixtures were found to deviate from the ideal mixtures. The degree of deviations reaches the maximum at about x(ACN)=0.7 with the presence of both homogeneous clusters of pure IL/ACN and heterogeneous clusters of IL-ACN. With the addition of ACN to IL, the mixtures undergo the transformation from “ACN solvated in [HOEmim][TFSI]” to “[HOEmim][TFSI] solvated in ACN”. It is found that the newly formed H-bonding interactions between the IL and ACN is the main factor that contributes to the red shifts of O−H, C₂−H, C_4,5−H, and C_alkyl−H of [HOEmim]⁺ cation, and the blue shifts of C−D, C≡N of ACN, and C−F, S=O of [TFSI]⁻ anion. These in-depth studies on the mixtures of hydroxyl-functionalized IL and acetonitrile would help to understand the micro-heterogeneity and H-bonding interactions of miscible solutions and shed light on exploring their applications.

中文翻译：

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跟踪羟基官能化离子液体溶液中的微异质性和氢键相互作用：一项联合实验和计算研究

离子液体 (IL) 是一类重要的介质，通常与极性溶剂结合使用以降低成本并调整其物理化学性质。在这方面，必须了解添加溶剂对离子液体特性的影响。在这项工作中，通过衰减全反射傅里叶变换红外光谱和分子模拟研究了羟基官能化 IL、[HOEmim][TFSI] 和乙腈 (ACN) 之间的微观异质性和 H 键相互作用。发现所有研究的 IL-ACN 混合物都偏离了理想混合物。偏差度在大约x处达到最大值(ACN)=0.7，同时存在纯 IL/ACN 的同质簇和 IL-ACN 的异质簇。将 ACN 添加到 IL 后，混合物会从“ACN 在 [HOEmim][TFSI] 中溶剂化”转变为“[HOEmim][TFSI] 在 ACN 中溶剂化”。发现IL和ACN之间新形成的H键相互作用是导致O-H、C ₂ -H、C _4,5 -H和C_烷基-H红移的主要因素[ HOEmim] ⁺阳离子，ACN 的 C−D、C≡N 和 [TFSI] 的 C−F、S=O 的蓝移^-阴离子。这些对羟基官能化离子液体和乙腈混合物的深入研究将有助于了解混溶溶液的微观异质性和氢键相互作用，并为探索它们的应用提供线索。