Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale). In the following section, we discuss in some detail their applications to the four scales of ILs, including molecular scale structures, mesoscale aggregates and dynamics, and unit scale reactor design and process design and optimization of typical IL applications. Finally, we address the concluding remarks of multiscale strat...

Multiscale Studies on Ionic Liquids

Does the stability of proteins in ionic liquids obey the Hofmeister series

The nature of solvent-biomolecule interactions is generally weak and non-specific. The addition of ionic liquids (ILs), which have emerged as a new class of solvents, strengthen the stability of some proteins whereas the same ILs weaken the stability of some other proteins. Although ILs are commonly used for the stabilization of biomolecules, the bimolecular interactions of their stabilization-destabilization is still an active subject of considerable interest and studies on this topic have been limited. To reveal the impact of ILs on the stability of proteins, a series of protic ILs possessing a tetra-alkyl ammonium cation [R4N](+) with a hydroxide [OH](-) anion were synthesized. In this study, we report the structural stability of heme proteins such as myoglobin (Mb) and hemoglobin (Hb) in a series of ammonium-based ILs such as tetramethyl ammonium hydroxide [(CH3)4N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C4H9)4N](+)[OH](-) (TBAH) by fluorescence and circular dichroism (CD) spectroscopic studies. Our experimental results reveal that less viscous ILs carrying smaller alkyl chain such as TMAH are strong destabilizers of the heme proteins as compared to the ILs carrying bulkier alkyl chains which are more viscous ILs, such as TBAH. Therefore, our results demonstrate that the addition of these ILs to the heme proteins decreases their thermal stability allowing the protein to be in an unfolded state at lower temperatures. Further, we describe the molecular-structural interaction of the heme proteins with the ILs (molecule like a ligand) by the PatchDocking method.

Unexpected effects of the alteration of structure and stability of myoglobin and hemoglobin in ammonium-based ionic liquids

Biocompatibility of ionic liquids towards protein stability: A comprehensive overview on the current understanding and their implications

https://cyberleninka.org/article/n/692299.pdf

Task-specific thioglycolate ionic liquids for heavy metal extraction: synthesis, extraction efficacies and recycling properties

Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R4N]+ with commonly used anion hydroxide [OH]− were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R4N]+[OH]− are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH3)4N]+[OH]− (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N]+[OH]− (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N]+[OH]− (TPAH) and tetrabutyl ammonium hydroxide [(C4H9)4N]+[OH]− (TBAH). The alkyl chain length effect has been analyzed by precise measurements su...

Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

Thermophysical properties for the mixed solvents of N-methyl-2-pyrrolidone with some of the imidazolium-based ionic liquids

Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R₄N]⁺ with commonly used anion hydroxide [OH]⁻ were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R₄N]⁺[OH]⁻ are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH₃)₄N]⁺[OH]⁻ (TMAH), tetraethyl ammonium hydroxide [(C₂H₅)₄N]⁺[OH]⁻ (TEAH), tetrapropyl ammonium hydroxide [(C₃H₇)₄N]⁺[OH]⁻ (TPAH) and tetrabutyl ammonium hydroxide [(C₄H₉)₄N]⁺[OH]⁻ (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (Vᴱ), the deviation in isentropic compressibility (Δκₛ) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich–Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

T. Kavitha

Papers

Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

Thermophysical properties for the mixed solvents of N-methyl-2-pyrrolidone with some of the imidazolium-based ionic liquids

Influence of Alkyl Chain Length and Temperature on Thermophysical Properties of Ammonium-Based Ionic Liquids with Molecular Solvent B

Temperature dependence measurements and molecular interactions for ammonium ionic liquid with N-methyl-2-pyrrolidone

Influence of temperature on thermophysical properties of ammonium ionic liquids with N-methyl-2-pyrrolidone