This work reports new experimental data on density and viscosity of pure ionic liquids (ILs) based on trifluoromethanesulfonate anion, [CF3SO3]. In particular, a cation-core effect on these basic solvent characteristics is demonstrated and investigated. The studied structures comprise representative 1-butyl-1-methylpyrrolidinium, 1-butyl-1-methylpiperidinium, and 1-butyl-3-methylpyridinium cations. In the main part of this work, the possibility to form aqueous biphasic systems (ABS) based on the studied ILs and four carbohydrates, namely, D-(+) -glucose, D-(-)-fructose, D-sorbitol, and xylitol, was tested. Liquid liquid equilibrium phase diagrams at T = 298.15 K, including binodal curves and tie lines, were determined for 12 distinct ABS, and then, an impact of the type of cation of IL (pyrrolidinium, piperidinium, and pyridinium) on these properties was elucidated and discussed in terms of the molecular structure of both ILs and carbohydrates and molecular interactions between them. Moreover, an effect of temperature on ABS formation is also presented for a selected representative system.