Reciprocity between ion-dipole and hydrogen bond interactions in the binary mixtures of N,N-Dimethylformamide with ionic liquids

Abstract

In this work, classical molecular dynamics (MD) simulations were carried out to investigate the structure and dynamics of binary mixtures of N, N-dimethylformamide (DMF) and ionic liquids (ILs), diethylammonium acetate (DEAA) and triethylammonium acetate (TEAA), with the change in mole fraction of ILs. The hydrogen bonding, dipole-dipole, and ion-dipole interactions were exclusively studied to explore the structural as well as dynamical evolution produced by the number of ionic entities in the mixtures. We have calculated the structural properties such as radial distribution functions (RDFs), spatial distribution functions (SDFs), and coordination numbers. These calculations were followed by studies involving dynamic properties like diffusion coefficients, hydrogen bond relaxation, and residence times. RDFs indicate the long-range correlations between ions in pure ILs. Structural properties also reveal an increase in ion-dipole interactions between DMF and ILs at high mole fractions of IL. These binary mixtures show high ion mobility at lower concentrations of ILs. Overall, the acetate anions show slightly higher diffusion than ammonium cations in pure ILs, and these two ions exhibit enhanced dynamics in the mixtures rich in DMF.