Properties of Apolar Solutes in Alkyl Imidazolium‐Based Ionic Liquids: The Importance of Local Interactions

Abstract

The solvation and the dynamic properties of apolar model solutes in alkyl imidazolium-based ionic liquids (IL) are studied by using all-atom molecular dynamics simulations. In regards to specific IL effects, we focused on the often used 1-ethyl-3-methyl imidazolium cation in combination with the anions tetrafluoroborate, acetate, and bis(trifluoromethanesulfonyl)imide. Our findings reveal that the size of the anion crucially influences the accumulation behavior of the cations, which results in modified IL solvation properties. Deviations between the different alkyl imidazolium-based IL combinations can be also observed with regard to the results for the radial distribution functions, the number of surrounding molecules, and the molecular orientation. The analysis of the van Hove function further shows pronounced differences in the dynamic behavior of the solutes. The simulations verify that the solute mobilities are mainly influenced by the composition of the local solvent shell and the properties of the underlying Lennard-Jones interactions. Additional simulations with regard to modified short-range dispersion energies for alkyl imidazolium-based ILs validate our conclusions.

Computational analysis of the solvation of coffee ingredients in aqueous ionic liquid mixtures

“…8a) but turns to a dominance of coulombic interactions for gallic acid and quercetin which is most probably due to the existence of hydroxy groups in the phenolics. In a model study 76 C 2 mim ⊕ also showed three times larger dispersion energy with an artificial sphere compared to acetate.…”

Dissecting the Vaporization Enthalpies of Ionic Liquids by Exclusively Experimental Methods: Coulomb Interaction, Hydrogen Bonding, and Dispersion Forces

“…[5][6][7][8] Moreover,t he theoretical methods have their shortcomings for describing the liquid phase.DFT-calculated gas phase clusters do not mimic the complex situation in the bulk, and MD simulations suffer from insufficient parametrization of charges and Lennard-Jones parameters. [19][20][21] Despite improvements in experiment and theory,for example,byconsidering polarizabilities in MD simulations,p redicting and dissecting vaporization enthalpies remains achallenge. [19][20][21] Despite improvements in experiment and theory,for example,byconsidering polarizabilities in MD simulations,p redicting and dissecting vaporization enthalpies remains achallenge.…”

“…[9][10][11][12][13][14][15][16][17][18] Theuse of reduced charges to better describe the transport properties of ILs automatically leads to decreased Coulomb interaction in favor of van der Waals forces without any physical evidence. [19][20][21] Despite improvements in experiment and theory,for example,byconsidering polarizabilities in MD simulations,p redicting and dissecting vaporization enthalpies remains achallenge. [22][23][24] In essence,v aporization enthalpies provide information about the total energy,w hich is needed to overcome the overall interaction energy between the liquid constituents.…”

Innenrücktitelbild: Zerlegung der Verdampfungsenthalpien ionischer Flüssigkeiten durch rein experimentelle Methoden: Coulomb‐Wechselwirkung, Wasserstoffbrücken und Dispersionskräfte (Angew. Chem. 25/2019)

“…[9][10][11][12][13][14][15][16][17][18] Die Nutzung reduzierter Ladungen zur besseren Beschreibung der Transporteigenschaften von ILs führt unweigerlich zu niedrigeren Coulomb-Wechselwirkungen zugunsten von van-der-Waals-Wechselwirkungen, ohne dass dafürk onkrete Belege existieren. [19][20][21] Tr otz Verbesserungen experimenteller und theoretischer Methoden, z. B. durch Berücksichtigung von Polarisierbarkeiten in MD-Simulationen, bleibt die Vorhersage und Zerlegung von Verdampfungsenthalpien ein schwieriges Unterfangen.…”