Copper(II) Chloro Complex Formation Thermodynamics and Structure in Ionic Liquid, 1-Butyl-3-Methylimidazolium Trifluoromethanesulfonate

Proton Thermodynamics in a Protic Ionic Liquid, Ethylammonium Nitrate

In order to investigate the proton solvation state in protic ionic liquids (PILs), ten acid dissociation enthalpies and entropies of eight compounds were determined in ethylammonium nitrate (EAN). Regardless of the nature of the compound, 24 kJ mol^-1 larger enthalpy and 65 J mol^-1  K^-1 larger entropy than those in water, respectively, were observed. These values were reasonably explained by the differences in the proton solvation structure in EAN and water. Namely, protons in EAN exist as HNO₃ , having a higher reaction energy than that of H₃ O⁺ in water, undergo entropic stabilization as a result of the less-structured solvation. As such, the entropic effect of the proton solvation structure on the acid-base property is possibly applicable to all PILs. In addition, based on these proton thermodynamics, enthalpy and entropy windows were proposed as a novel perspective for the characterization of solvents. Use of this concept enabled the visualization of similarities and differences between EAN and water.

Effects of the long octyl chain on complex formation of nickel(ii) with dimethyl sulfoxide, methanol, and acetonitrile in ionic liquid of [C8mim][TFSA]

The mono-DMSO complex is formed in [C₈mim][TFSA]-DMSO solutions, but not in [C₂mim][TFSA]-DMSO solutions.