Unknown crystal-like phases formed in an imidazolium ionic liquid: A metadynamics simulation study.

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Crystal polymorphism is vital in industrial crystallization, pharmaceuticals, and materials engineering.
• Identifying new crystal structures in complex, high-viscosity liquids like ionic liquids (ILs) presents experimental challenges.

Purpose of the Study:

• To investigate the crystal polymorphism of imidazolium-based ionic liquids (ILs) using advanced simulation techniques.
• To explore and identify previously unknown crystal structures and phases in ILs.

Main Methods:

• Utilized molecular dynamics (MD) simulations combined with metadynamics.
• Employed Gaussian window functions representing two distinct radial-distribution functions as collective variables.

Main Results:

• Discovered at least two novel crystal-like phases beyond the known alpha and beta phases for the studied imidazolium IL.
• Identified a unique phase characterized by ordered anion aggregations, independent of the simulation potential used.

Conclusions:

• The simulation methodology is effective for exploring unknown phases in complex systems.
• Findings contribute to the design of functional materials, including porous ILs for gas separation and capture.