“…A number of works now aim at studying the structure and interionic interactions in tertiary alkylammonium PILs. ,,, The tertiary cation in these cases demonstrates a marked ability to act as a proton donor (due to a single N–H site) and to form one strong and directional hydrogen bond with the acid anion. In our earlier DFT studies, − we obtained numerous correlations between the quantum chemical calculations of the ion pairs with a tertiary cation and experimental data on the physicochemical properties of the corresponding PILs. Furthermore, all these studies indicated that the magnitude of the interaction energies of the ion pairs of the triethylammonium class of PILs was significantly lower than that for the PILs with a triethanolammonium cation, which in turn led to the increase in the viscosity and decrease in the electric conductivity of the latter. , The H-bonding interaction in the ion pairs of triethylammonium-based PILs with different anions tended to become stronger with the increase in the anion proton affinity .…”