Structure-making tendency of ionic liquids in the aqueous d-glucose solutions

Densities (d) of d-glucose + ionic liquid {1-pentyl-3-methylimidazolium bromide ([PnMIm]Br) and 1-hexyl-3-methylimidazolium bromide ([HMIm]Br)} + water ternary solutions were measured at T = 288.15, 298.15, 308.15 and 318.15 K as a function of d-glucose molality in 0.2, 0.3, 0.4 and 0.5 mol kg−1 of ionic liquids. The measured density values were used to calculate the standard partial molar volume (Vϕ0), partial molar expansivity (Eϕ0), hydration number (nH) and volumetric interaction coefficients (VSILVSIL and VSILILVSILIL) at different temperatures. These parameters have been discussed in terms of solute–solvent interactions and structure making/breaking abilities of d-glucose and ionic liquids. It is also attempted to understand the effects of cation size of ionic liquid and temperature on the volumetric properties. The results show that the longer alkyl chain of ionic liquid has the stronger interactions with d-glucose and this type of interactions is further increased at high temperatures.

► The [HMIm]Br and [PnMIm]Br ionic liquids was synthesized.
► Volumetric properties of d-glucose with ionic liquids have been investigated.
► Structure-making tendency of d-glucose in presence of ionic liquids was increased.