Thermally-Stable Imidazolium Dicationic Ionic Liquids with Pyridine Functional Groups

Abstract

Thermally-stable ionic liquids (ILs) have limited structural possibilities and lack coordinating anions or functional groups. Thermal stability effectively incurs a tunability penalty, limiting ionic liquid function to render them as simple heat-stable fluids. In this work, a series of new thermally-stable dicationic ionic liquids with pyridine functional groups, abbreviated [(C8ImC1)2Py]­[A]2, are presented and compared to nonfunctional geminal dicationic ILs. All ILs have been thermally characterized to understand their elevated temperature stabilities and the processes that lead to their decomposition. Importantly, functional [(C8ImC1)2Py]­[A]2 with noncoordinating anions (i.e., [NTf2]−) have thermal stabilities comparable to those of geminal dicationic ILs, with the added advantage of a functional pyridine moiety. Dissolution of Zn­[NTf2]2 in [(C8ImC1)2Py]­[NTf2]2 is demonstrated, and the resulting solutions are characterized to show their liquid properties, high thermal stabilities, and the coordination of the metal center to the functional group. This is the first example of a thermally-stable functional IL with the potential to reclaim the tunable, task-specific nature of ILs at elevated temperatures. Importantly, these properties open new avenues for high-temperature applications of IL by extending their operational ranges; catalysis, metal remediation, and separation-based applications are potential key areas of improvement.

Controlling surface chemistry and mechanical properties of metal ionogels through Lewis acidity and basicity

“…S46 †). 40 However, thermal stability of the [omim][NTf 2 ]-0.33 Zn[NTf 2 ] 2 ionogel with 30% PEGDA was signicantly compromised when compared to the Zn free ionogel analogue (T onset reduce by 173 C). Furthermore, reducing the quantity of Zn did not improve thermal stability, and even small quantities of Zn (i.e., c ¼ 0.05) signicantly impacted ionogel thermal stability (ESI, Fig.…”

Application of Ionic Liquids for Chemical Demulsification: A Review

“…Ionic liquids have been widely used in different fields like pharmaceutical, oil and gas, and chemical industries [ 53 , 54 , 55 , 56 , 57 , 58 ], such as in pharmaceutical products manufacturing [ 59 , 60 , 61 , 62 ], viscosity modifiers [ 63 ], desulfurization of liquid fuels [ 64 ], and liquid-liquid extraction [ 65 , 66 , 67 ]. Several types of ionic liquids, such as polymeric ionic liquids [ 68 , 69 , 70 ], double salt ionic liquids [ 71 ], dicationic ionic liquids [ 72 , 73 , 74 , 75 ], deep eutectic solvents [ 76 , 77 , 78 , 79 ], chiral ionic liquids [ 80 ], and solvate ionic liquids [ 81 , 82 ], have been synthesized for different aforementioned purposes.…”

Expanding the Chemical Space of Benzimidazole Dicationic Ionic Liquids

“…The reason for this sustained interest in ILs lies in their structural variability, which makes it possible to design suitable matching ions for a given application [5]. Although ILs exhibit unique properties and potential such as unmatched ability to dissolve several biopolymers [6,7], high thermal stability [8,9], high ability to solubilize gas [10], and high refractive index [11], the reputation of ILs as "green" solvents is certainly ascribable to their negligible vapor pressure, which makes them safe when compared to traditional organic solvents [12,13]. In fact, ILs are practically non-flammable [14], and the possibility of accidental spills is negligible.…”