Key Laboratory for Utility of Environment-Friendly Composite Materials and Biomass in Universities of Gansu Province, Department of Chemical Engineering, Northwest Minzu University, Lanzhou 730000, China.
College of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, China.
Molecules. 2019 Aug 27;24(17):3112. doi: 10.3390/molecules24173112.
Tunable properties prompt the development of different "tailor-made" functional ionic liquids (FILs) for specific tasks. FILs with an ether group are good solvents for many organic compounds and enzymatic reactions. However, ionic composition influences the solubility by affecting the physiochemical properties of these FILs. To address the structure effect, a series of novel FILs with a mono-ether group (ME) based on imidazole were prepared through cationic functionalization and anionic exchange reactions, and characterized by NMR, mass spectroscopy, and Thermogravimetric analysis (TGA). The effect of ionic composition (cationic structure and anions) on density, viscosity, ionic conductivity, electrochemical window, and thermal properties of these ME-FILs were systematically investigated. In general, the viscosity and heat capacity increases with the bigger cationic volume of ME-FILs; in particular, the 2-alkyl substitution of imidazolium enhances the viscosity remarkably, whereas the density and conductivity decrease on the condition of the same [NTf] anion; For these ME-FILs with the same cations, the density follows the order of [NTf] > [PF] > [BF]. The viscosity follows the order of [PF] > [BF] > [NTf]. Ion conductivity follows the order of [NTf] ≈ [BF] > [PF]. It is noted that the dynamic density has a good linear relationship with the temperature, and the slopes are the same for all ME-FILs. Furthermore, these ME-FILs have broad electrochemical windows and glass transition temperatures in addition to a cold crystallization and a melt temperature for ME-FIL. Therefore, the cationic structure and counter anion affect the physicochemical properties of these ME-FILs together.
可调谐性质促使人们开发出不同的“定制”功能离子液体（FIL），以满足特定任务的需求。具有醚基团的 FIL 是许多有机化合物和酶反应的良好溶剂。然而，离子组成通过影响这些 FIL 的物理化学性质来影响其溶解度。为了解决结构效应，通过阳离子官能化和阴离子交换反应，制备了一系列具有单醚基团（ME）的新型基于咪唑的 FIL，并通过 NMR、质谱和热重分析（TGA）进行了表征。系统研究了离子组成（阳离子结构和阴离子）对这些 ME-FIL 的密度、粘度、离子电导率、电化学窗口和热性能的影响。一般来说，ME-FIL 的粘度和热容随阳离子体积的增大而增大；特别是，咪唑鎓的 2-烷基取代会显著增加粘度，而在相同的 [NTf]阴离子条件下，密度和电导率会降低；对于具有相同阳离子的这些 ME-FIL，密度的顺序为 [NTf] > [PF] > [BF]。粘度的顺序为 [PF] > [BF] > [NTf]。离子电导率的顺序为 [NTf] ≈ [BF] > [PF]。值得注意的是，动态密度与温度呈良好的线性关系，所有 ME-FIL 的斜率都相同。此外，除了 ME-FIL 的冷结晶和熔融温度外，这些 ME-FIL 还具有较宽的电化学窗口和玻璃化转变温度。因此，阳离子结构和抗衡阴离子共同影响这些 ME-FIL 的物理化学性质。
