The following basic physicochemical properties were studied for both single-ion ILs (A, B) and DSILs (AB0.1-AB0.9): density and refractive index at 20 °C, as well as the characteristics of phase transformations in the temperature range from -80 °C to 120 °C. The two single-anion ILs exhibited values of density equal to 1.0511 (A) and 1.0886 g cm -3 (B), while all the studied DSILs possessed densities between these two values. The density dependence of xdic is shown in Fig. (detailed data are summarized in Table .8, Supplementary Data). These results