Two new ionic liquids derived from natural product salicylate, 1-methyl-3-ethylimidazolium salicylate ([Emim][Sal]) and 1,2-dimethyl-3-ethylimidazolium salicylate ([Emmim][Sal]), were synthesized and characterized. The density, surface tension, viscosity, and electrical conductivity of two ionic liquids were determined from 288.15 to 343.15 K. The physico−chemical properties of the ionic liquids were estimated from the experimental data by empiric or semi-empiric methods, such as, coefficients of thermal expansion, molecular volume, standard molar entropy, lattice energy, enthalpy of vaporization, and so on. According to the interstice model of ionic liquids, the interstice parameters like coefficients of thermal expansion and interstice volume etc. were estimated, too. The experimental results and Density Functional Theory (DFT) calculation were employed to discuss the structure characteristics caused by differences of cations/anions for properties of two ionic liquids. And by the Vogel–Fulcher–Tamman (VFT) equation, the temperature dependences of the ILs viscosities and electric conductivities were graphically described. The structures, the energetics and COSMO volumes of all investigated ions are obtained by combining DFT calculations and the COSMO–RS methodology to describe intermolecular interactions of ionic liquids.
本文合成并表征了两种新的离子液体,它们是从天然产物水杨酸衍生而来的,分别为1-甲基-3-乙基咪唑水杨酸盐([Emim][Sal])和1,2-二甲基-3-乙基咪唑水杨酸盐([Emmim][Sal])。测定了两种离子液体的密度、表面张力、粘度和电导率,温度范围为288.15至343.15K。通过经验或半经验方法,例如热膨胀系数、分子体积、标准摩尔熵、晶格能、汽化焓等,从实验数据估算了离子液体的物理化学性质。根据离子液体的间隙模型,还估算了间隙参数,如热膨胀系数和间隙体积等。实验结果和密度泛函理论(DFT)计算被用来讨论由阳离子/阴离子差异引起的两种离子液体性质的结构特征。通过Vogel-Fulcher-Tamman(VFT)方程,图形地描述了离子液体的粘度和电导率随温度的变化。通过结合DFT计算和COSMO-RS方法来描述离子液体的分子间相互作用,获得了所有研究离子的结构、能量和COSMO体积。