Toots Karl Marti, Sild Sulev, Leis Jaan, Acree William E, Maran Uko
Department of Chemistry, University of Tartu, 14a Ravila Street, Tartu 50411, Estonia.
Department of Chemistry, University of North Texas, 1155 Union Circle Drive #305070, Denton, Texas 76203-5017, United States.
Langmuir. 2024 Nov 12;40(45):23714-23728. doi: 10.1021/acs.langmuir.4c02628. Epub 2024 Oct 29.
This article presents an in-depth investigation into the influence of anionic structures of ionic liquids (ILs) on gas-ionic liquid partition coefficients (log ) of organic solutes in three ILs. While the primary objective was to examine whether there is a relationship between the molecular structure of the IL anion component and log , additionally it was looked at whether the molecular descriptors of the anion in the relationships encode possible molecular interactions during the miscibility and partitioning in the IL. The research involves the compilation of data series of experimental log values, where the cation component is constant. Such representative data series were obtained for three solutes─benzene, cyclohexane, and methanol─in three ILs with a uniform cationic component of methylimidazoliums. Using multiple linear regression models enhanced with machine learning techniques, the relationship between anionic structures and log values was successfully quantified and modeled. Systematically selected molecular descriptors describing the anion structure show that in the case of methanol log is strongly dependent on hydrogen bonds and Coulomb-dipolar interactions with the anion component, while in the case of benzene and cyclohexane the dispersion forces of the anion component are dominant. The outlier analysis and data interpretation highlight the need for extensive experimental data. The results confirm the initial hypothesis and provide valuable information on the role of the structure of the anionic component in determining the partitioning behavior of organic solutes. This knowledge is important for the design and optimization of ILs for specific applications, particularly as solvents in various industrial processes. The research also provides useful information about molecular interactions taking place in the interfaces of IL and organic additives in complex liquid media such as multicomponent electrolyte solutions, for example in energy storage applications.
本文深入研究了离子液体（ILs）的阴离子结构对三种离子液体中有机溶质的气-离子液体分配系数（log ）的影响。虽然主要目的是检验离子液体阴离子组分的分子结构与log 之间是否存在关系，但此外还研究了该关系中阴离子的分子描述符是否编码了在离子液体中的混溶和分配过程中可能的分子相互作用。该研究涉及编制实验log 值的数据系列，其中阳离子组分是恒定的。对于三种溶质——苯、环己烷和甲醇——在具有均匀阳离子组分甲基咪唑鎓的三种离子液体中获得了这样具有代表性的数据系列。使用通过机器学习技术增强的多元线性回归模型，成功地量化并建模了阴离子结构与log 值之间的关系。系统选择的描述阴离子结构的分子描述符表明，对于甲醇，log 强烈依赖于与阴离子组分的氢键和库仑 - 偶极相互作用，而对于苯和环己烷，阴离子组分的色散力占主导。异常值分析和数据解释突出了广泛实验数据的必要性。结果证实了最初的假设，并提供了关于阴离子组分结构在确定有机溶质分配行为中作用的有价值信息。这些知识对于设计和优化用于特定应用的离子液体很重要，特别是作为各种工业过程中的溶剂。该研究还提供了关于在复杂液体介质（如多组分电解质溶液）中离子液体与有机添加剂界面处发生的分子相互作用的有用信息，例如在能量存储应用中。
