Grupo de Nanomateriales y Materia Blanda, Departamento de Física de la Materia Condensada, Universidad de Santiago de Compostela, Campus Vida, s/n, E-15782 Santiago de Compostela, Spain.
J Phys Chem B. 2011 Sep 29;115(38):11170-82. doi: 10.1021/jp206341z. Epub 2011 Sep 7.
In this work, extensive molecular dynamics simulations of mixtures of alcohols of several chain lengths (methanol and ethanol) with the ionic liquids (ILs) composed of the cation 1-hexyl-3-methylimidazolium and several anions of different hydrophobicity degrees (Cl(-), BF(4)(-), PF(6)(-)) are reported. We analyze the influence of the nature of the anion, the length of the molecular chain of the alcohol, and the alcohol concentration on the thermodynamic and structural properties of the mixtures. Densities, excess molar volumes, total and partial radial distribution functions, coordination numbers, and hydrogen bond degrees are reported and analyzed for mixtures of the ILs with methanol and ethanol. The aggregation process is shown to be highly dependent on the nature of the anion and the size of the alcohol, since alcohol molecules tend to interact predominantly with the anionic part of the IL, especially in mixtures of the halogenated IL with methanol. Particularly, our results suggest that the formation of an apolar network similar to that previously reported in mixtures of ILs with water does not take place in mixtures with alcohol when the chloride anion is present, the alcohol molecules being instead homogeneously distributed in the polar network of IL. Moreover, the alcohol clusters formed in mixtures of [HMIM][PF(6)] with alcohol were found to have a smaller size than in mixtures with water. Additionally, we provide a semiquantitative analysis of the dependence of the hydrogen bonding degree of the mixtures on the alcohol concentration.
在这项工作中，我们对几种链长的醇（甲醇和乙醇）与由阳离子 1-己基-3-甲基咪唑和几种不同疏水性程度的阴离子（Cl(-)、BF(4)(-)、PF(6)(-)）组成的离子液体（ILs）混合物进行了广泛的分子动力学模拟。我们分析了阴离子的性质、醇分子链的长度和醇浓度对混合物热力学和结构性质的影响。报告并分析了 IL 与甲醇和乙醇混合物的密度、过量摩尔体积、总和部分径向分布函数、配位数和氢键程度。聚合过程高度依赖于阴离子的性质和醇的大小，因为醇分子倾向于主要与 IL 的阴离子部分相互作用，特别是在与甲醇的卤化 IL 混合物中。特别是，我们的结果表明，当存在氯离子时，在与醇的混合物中不会形成类似于先前在 IL 与水的混合物中报道的非极性网络，而是醇分子均匀地分布在 IL 的极性网络中。此外，我们发现[HMIM][PF(6)]与醇混合物中形成的醇簇比在与水的混合物中形成的醇簇小。此外，我们还对半定量分析了混合物氢键程度对醇浓度的依赖性。
