Given that the properties of DSILs are strictly dependent on the molar ratio between constituents, in this study we have attempted to further elucidate the phenomenon of synergistic action for DSILs for agrochemical applications and to find the optimal molar ratio of the parent ILs which will provide the most favorable properties. We have also provided a detailed spectral and physicochemical characterization of the new DSILs as well as preliminary evaluation of their aqueous toxicity toward model freshwater algae -Chlorella vulgaris.