Ab Initio Investigation of the Interionic Interactions in Triethylammonium-Based Protic Ionic Liquids: The Role of Anions in the Formation of Ion Pair and Hydrogen Bonded Structure

Abstract

The results of structural analysis and cation–anion interactions of 10 ion pairs and their relevance for the physicochemical properties of triethylammonium-based protic ionic liquids are reported. The calculations were mainly performed by dispersion corrected density functional theory method (B3LYP-GD3). It is shown that the dispersion correction is important in the evaluation of the interaction energies of these compounds. The role of anions in the formation of ion pairs and hydrogen-bonded structure are analyzed. To obtain a quantitative measure of the strength of H-bonds, the Bader’s theory of atoms in molecule (AIM) was applied. The correlations between hydrogen bond lengths, their energies, and electron-topological parameters at the H···O bond critical point are presented.

Integration of acetic acid catalysis with one-pot protic ionic liquid configuration to achieve high-efficient biorefinery of poplar biomass

“…[64][65][66] The B3LYP functional and Grimme's dispersion has been applied successfully and extensively used to study the structure and intermolecular interactions in the protic ionic liquids. 49,52,65,67,68 The cartesian coordinates of all the optimized structures along with their energy values were provided in the ESI. † COSMO-RS calculations.…”

“…The larger difference in proton affinities, the lower possibility of proton transfer between acid and base. 52,53 Thus, this study also investigated the effects of neutral species on biomass pretreatment. From Table 4, the excess enthalpy of biomass components in both [EOA][OAc] and its neutral species are displaying exothermic behavior, indicating the stronger interaction between biomass components and PIL species.…”

Modelling biocompatible ionic liquids based on organic acids and amino acids: challenges for computational models and future perspectives

“…In other words, if the position of equilibrium ( 1) is not known or uncertain, the possibilities of obtaining a clear-cut answer from simulations are rather limited. Useful indications can certainly be had from the accurate computations of proton transfer energy profiles in isolated pairs, 126,127 and from AIMD simulations, [128][129][130] but the reliable prediction of equilibrium (1) in condensed system still defies a straightforward computational approach.…”

Ion Pair Structures and Hydrogen Bonding in RnNH4–n Alkylammonium Ionic Liquids with Hydrogen Sulfate and Mesylate Anions by DFT Computations

“…A number of works now aim at studying the structure and interionic interactions in tertiary alkylammonium PILs. ,,, The tertiary cation in these cases demonstrates a marked ability to act as a proton donor (due to a single N–H site) and to form one strong and directional hydrogen bond with the acid anion. In our earlier DFT studies, − we obtained numerous correlations between the quantum chemical calculations of the ion pairs with a tertiary cation and experimental data on the physicochemical properties of the corresponding PILs. Furthermore, all these studies indicated that the magnitude of the interaction energies of the ion pairs of the triethylammonium class of PILs was significantly lower than that for the PILs with a triethanolammonium cation, which in turn led to the increase in the viscosity and decrease in the electric conductivity of the latter. , The H-bonding interaction in the ion pairs of triethylammonium-based PILs with different anions tended to become stronger with the increase in the anion proton affinity .…”

“…In our earlier DFT studies, − we obtained numerous correlations between the quantum chemical calculations of the ion pairs with a tertiary cation and experimental data on the physicochemical properties of the corresponding PILs. Furthermore, all these studies indicated that the magnitude of the interaction energies of the ion pairs of the triethylammonium class of PILs was significantly lower than that for the PILs with a triethanolammonium cation, which in turn led to the increase in the viscosity and decrease in the electric conductivity of the latter. , The H-bonding interaction in the ion pairs of triethylammonium-based PILs with different anions tended to become stronger with the increase in the anion proton affinity . An increase in the alkyl chain length of the cation and the degree of branching weakened the interaction between the ions in the trifluoroacetate-containing PILs with dimethylethyl, triethyl, tributyl, and diisopropylethylammonium cations .…”