A new force field model of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid and acetonitrile mixtures

Abstract

Recently, we introduced a new force field (FF) to simulate transport properties of imidazolium-based room-temperature ionic liquids (RTILs) using a solid physical background. In the present work, we apply this FF to derive thermodynamic, structure, and transport properties of the mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF(4)], and acetonitrile (ACN) over the whole composition range. Three approaches to derive a force field are formulated based on different treatments of the ion-ion and ion-molecule Coulomb interactions: unit-charge, scaled-charge and floating-charge approaches. The simulation results are justified with the help of experimental data on specific density and shear viscosity for these mixtures. We find that a phenomenological account (particularly, a simple scaled-charge model) of electronic polarization leads to the best-performing model. Remarkably, its validity does not depend on the molar fraction of [BMIM][BF(4)] in the mixture. The derived FF is so far the first molecular model which is able to simulate all transport properties of the mixtures, comprising RTIL and ACN, fully realistically.

Ion Correlation and Collective Dynamics in BMIM/BF4-Based Organic Electrolytes: From Dilute Solutions to the Ionic Liquid Limit

“…While previous studies have examined ion association and correlation in pure ionic liquids, 35,36,41 similar computational studies of dilute organic electrolytes have mostly focused on acetonitrile-based systems, 19,[42][43][44] and studies of electrolytes consisting of low-dielectric solvents are relatively scarse. Recently, solvation models have been proposed to predict 4 ion association constants, 45 and combined molecular simulations and quasi-elastic neutron scattering experiments have demonstrated correlation of ion association and ion dynamics with solvent dielectric strength.…”

Local Structure in Terms of Nearest-Neighbor Approach in 1-Butyl-3-methylimidazolium-Based Ionic Liquids: MD Simulations

“…[3][4][5] Despite an unprecedentedly detailed description of various structural and dynamical properties that can be accessible from molecular simulations, analysis of the results of such simulations is very often based solely on the radial distribution functions (RDFs) between centers of mass. [6][7][8][9][10] Moreover, many seminal computational studies on ILs have been performed either on a single IL or on a rather narrow family of systems, e.g., chlorides, for the sake of computational efficiency, while the results have been presented as universally applicable. 3,[11][12] However, such claims can turn out to be questionable.…”

The force field for imidazolium-based ionic liquids: Novel anions with polar residues

“…The good performance of this method was proven for a variety of room-temperature ionic liquids representing pyridinium and imidazolium M a n u s c r i p t families. [29,[43][44][45] The simulated AAILs can be compared to one another to derive qualitative insights into this novel class of ionic compounds.…”

“…We applied this approximation successfully in Ref. [29,[43][44][45] and obtained trustworthy predictions of structure and transport properties. Recall that only a single cation-anion coordination site was suggested by DFT calculations.…”