1. A Comparative Study of Solvation Dynamics in Different
Classes of Room-Temperature Ionic Liquids
Mark N. Kobrak, Department of Chemistry Brooklyn College and the Graduate Center of the City University of New York, 2900 Bedford Ave., Brooklyn, NY 11210
The Challenge:
Room-temperature ionic liquids, salts that are molten at room temperature, display complex time-dependent dynamics. Understanding these dynamics is necessary for interpreting reaction kinetics in ionic liquid solvents.
The Approach:
We use molecular dynamics to model the fluorescence of a coumarin-153, well-known dye, in a series of ionic liquids. Our results compare well to experiment, and can be broken down using statistical methods to characterize the molecular motions responsible for solvation.
Component Time Correlation Functions
The Conclusions:
Calculations on 3 different ionic liquids reveal two principles governing their fluorescence response:
Even for highly flexible molecules, the rovibrational response of the ion is far less important than the translational response.
Collective motion begins to dominate dynamics even on sub-picosecond timescales.
These principles will be prime determinants of ionic liquid kinetics.