Stokes shift dynamics of [Na][TOTO] – A new class of ionic liquids: A comparative study with more common imidazolium analogs

A semi-molecular theory has been employed to predict temperature dependent Stokes shift dynamics of a dipolar probe in sodium 2,5,8,11-tetraoxatridecan-13-oate ([Na][TOTO]), and compared with imidazolium ionic liquids (ILs). Predicted dynamic Stokes shift for [Na][TOTO]is ∼60–70% of that calculated for imidazolium ILs. The calculated biphasic dynamics is, however, extremely slow because of large viscosity, average solvation time (〈τss〉) being in ∼1 s–10 ns range at 254 ⩽ T/(K) ⩽ 344. This is much slower than those in imidazolium ILs (0.1 ⩽ 〈τss〉/ns ⩽ 6 at 278 ⩽ T/(K) ⩽ 338). Predicted temperature dependence of shift is very weak and suggests near-Arrhenius behavior for the dynamics.