Solvent fluctuation (GTFE-TFE) of 2,2,2-trifluoroethanol (TFE)–H2O mixture was determined by small-angle X-ray scattering investigation. Protein’s coil–helix transition can be induced by preferential binding of TFE (ΔΓ23) without aggregation of TFE.

Aqueous solutions of tetrabutylphosphonium trifluoroacetate, [P4444]CF3COO, exhibit a liquid-liquid phase transition with a lower critical solution temperature. Herein, we characterized the constituent ions, [P4444](+) and CF3COO(-), in terms of their effects on the molecular organization of H2O on the basis of 1-propanol probing methodology devised by Koga et al. The resulting characterization of the hydrophobicity/hydrophilicity is displayed on a two-dimensional map together with previous results, for a total of four cations and nine anions of typical ionic liquid (IL) constituents. The results indicate that [P4444](+) is the most significant amphiphile with strong hydrophobic and equally strong hydrophilic contributions among the group of constituent cations of ILs studied so far. The hydration number for [P4444](+) was evaluated to be nH = 72, which is three times larger than that of a typical imidazolium-based cation, [C4mim](+). Self-aggregation of [P4444](+) was found to occur in an aqueous solution of [P4444]CF3COO above 0.0080 mole fraction of the IL.

We determined the excess partial molar enthalpy and the excess partial molar volume, HTFE E , VTFE E , of 2,2,2-trifluoroethanol (TFE) in TFE-H2O at 25.0 ˚C. We then evaluate the TFE-TFE interactions in terms of enthalpy and volume, HTFE-TFE E and VTFE-TFE E , graphically without resorting to any model dependent fitting functions. Both model-free third derivatives indicate that TFE is a hydrophobic solute and that as other hydrophobic alkyl mono-ols there are three distinct mixing schemes, Mixing Scheme I, II, and III in their aqueous solutions. The relative strength in hydrophobicity between TFE and tertbutylalcohol (TBA), for example, gave a mixed message within the behavior of these third derivative quantities. We thus applied the 1-propanol(1P) probing methodology (Koga, Y.