Fumino Koichi, Fossog Verlaine, Stange Peter, Wittler Kai, Polet Wigbert, Hempelmann Rolf, Ludwig Ralf
Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 1, 18059, Rostock (Germany).
Chemphyschem. 2014 Aug 25;15(12):2604-9. doi: 10.1002/cphc.201402205. Epub 2014 Jun 12.
The cation-anion and cation-solvent interactions in solutions of the protic ionic liquid (PIL) [Et3NH][I] dissolved in solvents of different polarities are studied by means of far infrared vibrational (FIR) spectroscopy and density functional theory (DFT) calculations. The dissociation of contact ion pairs (CIPs) and the resulting formation of solvent-separated ion pairs (SIPs) can be observed and analyzed as a function of solvent concentration, solvent polarity, and temperature. In apolar environments, the CIPs dominate for all solvent concentrations and temperatures. At high concentrations of polar solvents, SIPs are favored over CIPs. For these PIL/solvent mixtures, CIPs are reformed by increasing the temperature due to the reduced polarity of the solvent. Overall, this approach provides equilibrium constants, free energies, enthalpies, and entropies for ion-pair formation in trialkylammonium-containing PILs. These results have important implications for the understanding of solvation chemistry and the reactivity of ionic liquids.
通过远红外振动（FIR）光谱和密度泛函理论（DFT）计算，研究了质子离子液体（PIL）[Et3NH][I]溶解在不同极性溶剂中的阳离子 - 阴离子和阳离子 - 溶剂相互作用。可以观察和分析接触离子对（CIP）的解离以及由此产生的溶剂分隔离子对（SIP）的形成，作为溶剂浓度、溶剂极性和温度的函数。在非极性环境中，对于所有溶剂浓度和温度，CIP占主导。在高浓度极性溶剂中，SIP比CIP更受青睐。对于这些PIL/溶剂混合物，由于溶剂极性降低，通过升高温度CIP会重新形成。总体而言，该方法提供了含三烷基铵的PIL中离子对形成的平衡常数、自由能、焓和熵。这些结果对于理解溶剂化化学和离子液体的反应性具有重要意义。
