Structural design and physicochemical specifications exploring of the new di-cationic ionic liquids (D-ILs) composed of para-xylyl linked N-Methylimidazolium cation and various anions: a full M06-2X computational study

Some of the quantum chemical computable characteristics of the new designed di-cationic ILs ([X][Y1-6](2)) (X = [p - C6H4(CH2MIM)(2)](2+) and Y1-6 = CH3CO2-, CF3CO2-, BF4-, ClO4-, CF3SO3- and PF6-) based on para-xylyl linked bis-(3-methyl-1-imidazolium) cation and various anions were investigated using density functional theory (DFT) at M062X/aug-ccpvdz level of theory. The geometrical characteristics, electrostatic potential maps, dispersion including interaction energies, natural charge and charge transfer (CT), topological specifications, reduced gradient density (RGD) plots, cathodic (V-CL) and anodic (V-AL) limits of potentials as well as electrochemical windows (ECW) were explored and evaluated. The obtained consequences for dispersion corrected interaction energies which are the consequences of the intermolecular hydrogen bonding and electrostatic interactions (- 212.06 to - 250.22 kcal mol(-1)) showed the following order [X][Y-1](2) > [X][Y-2](2) > [X][Y-3](2) > [X][Y-4](2) > [X][Y-5](2) > [X][Y-6](2). The electrostatic essence for the C-H...O and C-H...F hydrogen bonds in [X][Y1-6](2) D-ILs is verified by the consequences of the electron density analysis calculations. The following order for ECWs of the designed di-cationic ILs (D-ILs) was obtained: [X][CH3CO2](2) < [X][CF3SO3](2) < [X][CF3CO2](2) approximately equal to [X][BF4](2) approximately equal to [X][ClO4](2) approximately equal to [X][PF6](2). For D-ILs composed of CF3CO2-, BF4-, ClO4- and PF6- anions, it is predicted that the anodic stability limit in aqueous environment is controlled by the di-cation constructing part of the D-ILs.

Automated summary

The quantum chemical computable characteristics of new designed di-cationic ILs were investigated using density functional theory, revealing that the interaction energies are influenced by hydrogen bonding and electrostatic interactions.