Synthesis and characterization of magnetic ionic liquids containing multiple paramagnetic lanthanide and transition metal centers and functionalized diglycolamide ligands
Synthesis and characterization of magnetic ionic liquids containing multiple paramagnetic lanthanide and transition metal centers and functionalized diglycolamide ligands
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DOI：
10.1016/j.molliq.2022.119530
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发表时间：
2022-09-01
影响因子：
6
通讯作者：
Anderson, Jared L.
中科院分区：
文献类型：
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作者：
Abbasi, Nabeel Mujtaba;Zeger, Victoria R.;Anderson, Jared L.
含有顺磁性中心的磁性离子液体（MIL）由于其对外部磁场的响应能力而被广泛认为是可持续溶剂。MIL的物理化学性质取决于阴离子/阳离子配体和金属中心的选择;正在寻找可以赋予有利特性（例如低粘度）的高度可调的配体和前体。用作阳离子配体的二甘醇酰胺先前已显示形成疏水MIL，其可同时在阴离子/阳离子两者中并入多个镧系金属中心。尽管其增强的磁化率，二甘醇酰胺的化学结构修饰的物理化学性质的MIL的效果还没有得到彻底的研究。此外，还没有研究用普遍使用的过渡金属形成基于二甘醇酰胺的MIL的可能性，并且还没有探索可以同时在阴离子/阳离子中嵌入两种不同类型的金属中心的组合。在本研究中，通过检查它们与直链和支链二甘醇酰胺的螯合作用，合成了三十（30）种由镧系和过渡金属组成的MIL。发现基于过渡金属的MIL具有高达235摄氏度的高热稳定性，相比之下，由镧系元素组成的MIL具有192摄氏度的高热稳定性。虽然由稀土金属中心组成的MIL表现出最低的粘度，但仅在阴离子或阳离子中用过渡金属取代镧系元素导致增强的热稳定性和降低的粘度。这些MIL的有效磁矩在4.71和21.08 14之间变化，并且与使用相同金属制备的所有先前类别的MIL相比高得多。本研究的结果探索了可以对这些MIL进行的所有可能的修改，以证明它们的结构可调性，这在各种应用中通常是非常理想的，包括有机合成和化学分离。(C)2022爱思唯尔有限公司版权所有。
Magnetic ionic liquids (MILs) containing paramagnetic centers have gained widespread recognition as sustainable solvents due to their ability to respond to an external magnetic field. The physico-chemical properties of MILs are dependent on the choice of anion/cation ligands and metal centers; the search for highly tunable ligands and precursors that can confer favorable characteristics, such as low viscosity, is ongoing. Diglycolamides employed as cationic ligands have been previously shown to form hydrophobic MILs that can simultaneously incorporate multiple lanthanide metal centers in both the anion/cation. Despite their enhanced magnetic susceptibility, the effect of diglycolamide chemical structure modifications on the physico-chemical properties of MILs has not been thoroughly studied. Additionally, the possibility of forming diglycolamide-based MILs with popularly employed transition metals has not been investigated and combinations that can simultaneously embed two different types of metal centers in both the anion/cation have not been explored. In this study, thirty (30) MILs comprised of lanthanide and transition metals were synthesized by examining their chelation to both straight-chained and branched diglycolamides. Transition metal-based MILs were found to possess high thermal stabilities up to 235 degrees C compared to 192 degrees C for those comprised of lanthanides. While MILs comprised of rareearth metal centers exhibited the lowest viscosities, substituting lanthanides with transition metals in just the anion or cation resulted in enhanced thermal stability and reduced viscosity. The effective magnetic moment for these MILs varied between 4.71 and 21.08 14 and was much higher compared to all previous classes of MILs prepared using the same metals. Results from this study explore all possible modifications that can be made to these MILs in an effort to demonstrate their structural tunability, which is often highly desirable in various applications, including organic synthesis and chemical separations. (C) 2022 Elsevier B.V. All rights reserved.