First time investigation of the substitution effect at anion part of the ILs on their physicochemical properties using [DMT][4-XPhSO3] (X=NH2, OH, H, F, Br, CHO, CF3, CN and NO2) as a model ILs: A systematic DFT study

Abstract

Abstract In this study, a different class of high nitrogen content ionic liquids were designed. The physicochemical properties of [DMT][4-XPhSO3], (X = NH2, OH, H, F, Br, CHO, CF3, CN and NO2) IPs based on the triazolium cation and substituted benzene sulfonate anions were fully investigated using M06–2X functional in conjunction with the aug-ccpvdz basis set. For all of the designed ILs the structural parameters, interaction energy between constructing parts, enthalpy of formation, natural charges and topological properties were calculated and discussed. The effect of the substituent change at anion part on the interaction energy and physicochemical properties is taking into account for the first time. As revealed from the results, the strength of the interaction between constructing ionic parts had a linear correlation with the electron content of the anionic part in a way that the more stable ion pairs with higher interaction energies constructed as the electron content of the anionic part increased. Melting point, critical-point temperature, electrochemical stability and conductivity which are some of the important IL,s characteristic physical properties were estimated, compared with each other and discussed with the help of the quantum chemical computationally obtained thermochemical data for nine designed various X substituted [DMT][4-XPhSO3] ILs. Finally, the enthalpy and Gibbs free energy of the formation for nine various substituted anions were calculated.