Molecular dynamics simulation of geminal dicationic ionic liquids [C_n(mim)₂][NTf₂]₂ - structural and dynamical...

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Ionic liquids (ILs) are salts that are liquid at low temperatures, with tunable properties based on their chemical structure.
• Geminal dicationic ionic liquids (GDILs) offer unique properties due to their two cationic centers, making them promising for various applications.
• Understanding the molecular-level behavior of GDILs is crucial for optimizing their macroscopic properties.

Purpose of the Study:

• To investigate the structural and dynamical properties of imidazolium-based GDILs, specifically [C_n(mim)₂][NTf₂]₂ with n = 3 and 5.
• To elucidate the molecular basis governing the macroscopic and microscopic properties of these GDILs.
• To analyze the effect of linkage alkyl chain length on the thermodynamic, transport, and structural characteristics.

Main Methods:

• Molecular dynamics (MD) simulations were employed to study bulk liquid properties.
• Density functional theory (DFT) and Atoms in Molecule (AIM) methods were used for detailed interaction analysis.
• Key properties computed include diffusion coefficients, viscosity, conductivity, radial distribution functions, and heterogeneity parameters.

Main Results:

• Simulated properties showed good agreement with experimental data.
• The length of the alkyl linkage chain significantly influences the structural, dynamical, and thermodynamic properties of the GDILs.
• Analysis of radial distribution functions (RDFs) and spatial distribution functions (SDFs) characterized the structural heterogeneity.

Conclusions:

• The study provides a fundamental understanding of the structure-dynamics-property relationships in GDILs at a molecular level.
• The findings highlight the importance of alkyl chain length in tailoring GDIL performance.
• This work offers molecular insights complementing previous experimental studies on GDILs.