Abstract Despite a large collection of publications dealing with the characterization of ionic liquid-based aqueous biphasic systems (IL-ABS), a gap still exists regarding the impact of functionalized alkyl side branches and IL positional isomers on phase equilibria. Therefore, this work addresses the investigation of the ability of different methyl substituted pyridinium based ILs on the formation of ABSs with K3PO4. We evaluated the impact of (i) functional groups (hydroxyl or ether) embed in side alkyl chains of pyridinium cations, (ii) positional isomerism of methyl group (ortho, meta and para) and (iii) the IL cation core. Ternary phase diagrams of the ABSs formed by these ILs and K3PO4 and the appropriate tie lines were determined and presented. It is shown that the presence of functionalized alkyl chain largely affects the salting-in behavior of ILs (ILs with the oxygen groups are more difficult to form ABS) while more subtle differences were observed among positional isomers. Based on the obtained results it is concluded that change of biphasic area of ABS is the manifestation of the altered affinity of ILs for water as a consequence of cation structure. Moreover, aiming at gathering a broader picture of the relationship between ILs structure and ABS properties, molecular simulations were performed, and it was showed that the obtained results are consistent with the experimental results.

中文翻译：

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进一步了解吡啶鎓离子液体的官能化和位置异构对水性两相系统平衡的影响

摘要 尽管有大量出版物涉及基于离子液体的水性双相体系 (IL-ABS) 的表征，但在官能化烷基侧链和 IL 位置异构体对相平衡的影响方面仍然存在差距。因此，这项工作致力于研究不同甲基取代吡啶基离子液体与 K3PO4 形成 ABS 的能力。我们评估了（i）嵌入吡啶鎓阳离子侧烷基链中的官能团（羟基或醚），（ii）甲基（邻位、间位和对位）的位置异构和（iii）IL 阳离子核心的影响。确定并呈现了由这些 IL 和 K3PO4 形成的 ABS 的三元相图以及适当的连接线。结果表明，官能化烷基链的存在极大地影响了 ILs 的盐溶行为（带有氧基团的 ILs 更难形成 ABS），而在位置异构体之间观察到更细微的差异。基于获得的结果，得出结论：ABS双相面积的变化是由于阳离子结构导致ILs对水的亲和力改变的表现。此外，为了更广泛地了解 ILs 结构与 ABS 性能之间的关系，进行了分子模拟，结果表明所得结果与实验结果一致。基于获得的结果，得出结论：ABS双相面积的变化是由于阳离子结构导致ILs对水的亲和力改变的表现。此外，为了更广泛地了解 ILs 结构与 ABS 性能之间的关系，进行了分子模拟，结果表明所得结果与实验结果一致。基于获得的结果，得出结论：ABS双相面积的变化是由于阳离子结构导致ILs对水的亲和力改变的表现。此外，为了更广泛地了解 ILs 结构与 ABS 性能之间的关系，进行了分子模拟，结果表明所得结果与实验结果一致。