Fluorination effects on the physicochemical properties of the nanostructured tunable ionic liquids: [5F-PhMeTAZ]+ or [5H-PhMeTAZ]+ which one is the better choice?

Abstract

One of the routine ways to design ILs with better and different properties is using of various combinations of the cations and anions. To the best of our knowledge combination of halogenated cations with various anions to make ILs with different properties has not been considered well yet. In this study, the effects of adding fluorine atom to the cation part of the triazolium based ionic liquids (TILs) generally presented as [5F-PhMeTAZ][X1–9] (X1= NO3−, X2= CF3CO2−, X3= Cl−, X4= C(CN)3−, X5= Tf2N−-cis, X6= N(CN)2−, X7= Tf2N−-trans, X8= ClO4− and X9= BF4−) were investigated. The structural, electronic and physicochemical characteristics of the fluorinated TILs (FTILs) were calculated and compared with those of corresponding non fluorinated TILs (HTILs) with the general formula of [5H-PhMeTAZ][X1–9] (X1= NO3−, X2= CF3CO2−, X3= Cl−, X4= C(CN)3−, X5= Tf2N−-cis, X6= N(CN)2−, X7= Tf2N−-trans, X8= ClO4− and X9= BF4−). All of the calculations were carried out using the same level of theory (M06-2X/6-311++G(d,p)) which is previously used for investigation of the above mentioned HTILs due to obtain comparable results. The binding energy, volumetric and electron density properties, electrostatic maps, electrochemical windows, crystal lattice energy, anodic and cathodic limits for newly designed FTILs are calculated and discussed. In this study we get help Natural bond orbital (NBO) analysis and Atoms in molecules (AIM) theory to get deeper understanding about quality and nature of bonding and nonbonding interactions which could be influenced ILs properties. Finally, some physical characteristics such as melting point, conductivity, enthalpy of vaporization, and critical-point temperature of the nine studied FTILs were estimated and also compared stand on the data obtained from quantum chemical calculations during this research.