Research

Research Interests

Simulation of Room-Temperature Ionic Liquids:

 Room-Temperature Ionic Liquids (RTILs) are salts that are molten at room-temperature. It has recently been discovered that RTILs can solvate organic compounds, and generally display solvation properties comparable to those of moderately polar organic solvents. This gives RTILs considerable potential as industrial solvents, as they are nonvolatile and could therefore eliminate the health and liability concerns associated with emissions from existing industrial solvents.
Some Common Ions Used in Ionic Liquids

Solvation Properties: We use a combination of molecular dynamics simulation and analytical theory to explore RTILs at a microscopic level. Our goal is to characterize how ionic structure and liquid properties affect both thermodynamic and kinetc aspects of solvation. Ion-ion interactions in ionic liquids are much stronger than ion-dipole interactions, which has profound implications for the solvation of molecular solutes. We have found that solvation thermodynamics can be understood when one recognizes two facts: The presence of the solute does not significantly disrupt the charge-ordering of the neat liquid, but the liquid (a conductor) must screen the molecular dipole. The balance of these two phenomena permits an analytical description of the distribution of charge about a molecular solute. Likewise, we have also characterized the ionic motions underlying solvation dynamics, and have found ionic motion to be highly collective, even at the shortest accessible timescales.

Viscosity: We have developed an analytical theory describing the relationship between ionic structure and liquid viscosity. Where distributions of charge and mass are asymmetric in an ion, inter-ion Coulomb interactions couple to librational motion. Because ionic rotational motion is much faster than translational motion in ionic liquids, these couplings facilitate dynamic processes such as ionic diffusion and viscous flow. We have already developed a quantitative metric called the "charge arm" that permits prediction of the relative viscosities liquids composed of rigid ions of comparable mass. We are currently working to extend this treatment so that it can be applied more quantitatively.

Research Group

Current Members:

Hualin Li: PhD Student in Chemistry. Mr. Li is studying the relationship between ionic structure and viscosity in ionic liquids.


Former Members:
Dr. Vasiliy Znamenskiy: Post-doctoral fellow, 2002-2003. Vasiliy carried out molecular dynamics simulations on the solvation of Reichardt's Dye (betaine-30) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. His work provides some of the first detailed pictures of solute-solvent interactions in ionic liquids. He is currently working with Prof. Michael Green of City College of New York, CUNY.