Effect of an ionic liquid on the volumetric behavior of tetradentate N2O2 type Schiff bases in DMF at T = (308.15 to 328.15) K

tDensities of ternary mixtures of some Schiff bases N,N′-salicylidenephenylediamine (Salophen), N,N′-bis(salicylaldehyde)-1,3-diaminopropane (Salpr), N,N-bis(salicylidene)-1,2-cyclohexadiamine (Salcn) + ionic liquid, 1-penthyl-3-methylimidazolium bromide ([PnMIm]Br) + N,N-dimethylformamide have been measured at (308.15, 318.15 and 328.15) K. These data have been used to calculate apparent molar volume, VϕVϕ, the standard partial molar volume, Vϕ0, standard partial molar volume of transfer, ΔtrVϕ0, standard partial molar isobaric expansion, EP,ϕ0 and isobaric thermal expansion coefficient (α) for the mixtures studied. All these parameters were used to interpret the effect of ionic liquid on the solute–solvent interactions and solvation behavior occurring between ionic liquid and Schiff bases in these ternary mixtures.

► Volumetric properties of [PnMIm]Br + Schiff base + DMF were studied.
► Schiff bases predominantly acts as a structure maker.
► Structure making tendency is strengthening with increasing ionic liquid.
► The nonpolar–nonpolar interactions between Schiff base and ionic liquid are dominant in the studied mixtures.