Apparent molar volume, conductivity, and fluorescence studies of ternary systems of dipeptides + ionic liquids ([Cnmim]Br, n = 10, 14) + water at different temperatures

Densities, conductivities, and fluorescence spectra of two imidazolium ionic liquids ([Cnmim]Br, n = 10, 14)-glycyl dipeptide-water mixtures were measured as a function of temperature. The density data have been utilized to calculate the apparent molar volumes, standard partial molar volumes (V2,φ0), standard partial molar volumes of transfer from water to aqueous ionic liquids solutions (ΔtV°), the hydration number (NH), partial molar expansibility (Eφ0), and Hepler’s constant of glycyl dipeptides. Through the electrical conductivity measurements, the ccmc values at different temperatures and a series of thermodynamic parameters (ΔGmo, ΔHmo, and ΔSmo) of micellization of [Cnmim]Br (n = 10, 14) in aqueous glycyl dipeptides solutions are evaluated. The pyrene fluorescence spectra were used to study the change of micropolarity produced by the interaction of [Cnmim]Br with glycyl dipeptide, and the aggregation behavior of [Cnmim]Br (n = 10, 14). The results shown above have been explained in terms of solute–solvent interactions and structural changes in the mixed solutions. The interaction between [Cnmim]Br (n = 10, 14) and glycyl dipeptide is affected by temperature and hydrocarbon chain length of the dipeptides.