Structure of cholinium glycinate biocompatible ionic liquid at graphite electrode interface

Adsorption of Choline Phenylalanilate on Polyaromatic Hydrocarbon-Shaped Graphene and Reaction Mechanism with CO2: A Computational Study

The interaction of ionic liquids (ILs) with carbon materials is of fundamental importance in several areas of materials science, physics, and chemistry. Their adsorption on pristine and N-doped graphene surfaces is discussed here on the basis of results of density functional theory calculations. The nature of adsorption was investigated for an amino acid (AA)-based IL consisting of the choline cation [Ch] and the l-phenylalanilate anion [Phe] that interacts with a sheet of N-doped graphene. The interaction mechanism, binding energy, electron density, and non-covalent interaction analysis were evaluated by considering the cation, anion, and ion pair adsorbed on graphene separately. The distribution of cations and anions in the liquid bulk and on the graphene surface was then analyzed by molecular dynamics simulations. Since AA-based ILs are efficient absorbents for capture of CO2 due to the pronounced affinity of carbon dioxide to react with amino groups, we investigated the capacity of [Ch][Phe] to react with CO2 under various conditions. We considered the multistep mechanism of the reaction of [Phe] with CO2 first for the anion in the liquid bulk and then for the [Phe] anion adsorbed on the graphene surface. The initial step, the formation of the zwitterionic addition product, is followed by its structural rearrangement through intramolecular proton transfer and conformational isomerization processes to form carboxylic acid derivatives. The entire mechanism was evaluated for the [Phe] anion before and after adsorption on graphene to investigate how interactions with surfaces of carbon materials can affect the CO2 capture capacity of an AA-based IL such as [Ch][Phe].

Microstructures of Choline Amino Acid based Biocompatible Ionic Liquids

Bio-compatible ionic liquids (Bio-ILs) represent a class of solvents with peculiar properties and exhibit huge potential for their applications in different fields of chemistry. Ever since they were discovered, researchers have used bio-ILs in diverse fields such as biomass dissolution, CO2 sequestration, and biodegradation of pesticides. This review highlights the ongoing research studies focused on elucidating the microscopic structure of bio-ILs based on cholinium cation ([Ch]+ ) and amino acid ([AA]- ) anions using the state-of-the-arta b i n i t i o ${ab\hskip0.25eminitio}$ and classical molecular dynamics (MD) simulations. The microscopic structure associated with these green ILs guides their suitability for specific applications. ILs of this class differ in the side chain of the amino acid anions, and varying the side chain significantly affects the structure of these ILs and thus helps in tuning the efficiency of biomass dissolution. This review demonstrates the central role of the side chain on the morphology of choline amino acid ([Ch][AA]) bio-ILs. The seemingly matured field of bio-ILs and their employment in various applications still holds significant potential, and the insights on their microscopic structure would steer the field of target specific application of these green ILs.

Dielectric relaxation and dielectric decrement in ionic acetamide deep eutectic solvents: Spectral decomposition and comparison with experiments

Frequency-dependent dielectric relaxation in three deep eutectic solvents (DESs), (acetamide+LiClO4/NO3/Br), was investigated in the temperature range, 329 ≤ T/K ≤ 358, via molecular dynamics simulations. Subsequently, decomposition of the real and the imaginary components of the simulated dielectric spectra was carried out to separate the rotational (dipole-dipole), translational (ion-ion), and ro-translational (dipole-ion) contributions. The dipolar contribution, as expected, was found to dominate all the frequency-dependent dielectric spectra over the entire frequency regime, while the other two components together made tiny contributions only. The translational (ion-ion) and the cross ro-translational contributions appeared in the THz regime in contrast to the viscosity-dependent dipolar relaxations that dominated the MHz-GHz frequency window. Our simulations predicted, in agreement with experiments, anion-dependent decrement of the static dielectric constant (ɛs ∼ 20 to 30) for acetamide (ɛs ∼ 66) in these ionic DESs. Simulated dipole-correlations (Kirkwood g factor) indicated significant orientational frustrations. The frustrated orientational structure was found to be associated with the anion-dependent damage of the acetamide H-bond network. Single dipole reorientation time distributions suggested slowed down acetamide rotations but did not indicate presence of any "rotationally frozen" molecule. The dielectric decrement is, therefore, largely static in origin. This provides a new insight into the ion dependence of the dielectric behavior of these ionic DESs. A good agreement between the simulated and the experimental timescales was also noticed.