Department of

Computational Biological Chemistry

FWF P23494: Polarization forces in molecular ionic liquids

grant holderProf. O. Steinhauser
co-authorAss.-Prof. C. Schröder
funding period03/2012 - 05/2017
project sum187 k €

Abstract

Molecular ionic liquids are molten salts with a melting point below 373 K. Most of them consist of a imidazolium based cation and a weakly basic anion like triflate, dicyanoamide or bis(trifluoromethane)sulfonimide. Changing the cation or anion respectively, one can generate a large diversity of physical properties. Although remnant features of a charge ordered salt are visible, molecular ionic liquids show a translational and rotational dynamics which is slower but comparable to that of neutral molecular liquids. So far, the structure and single-particle dynamics of these systems was studied by simulations using pairwise additive forces. They do not consider the response of the molecular charge distribution to the local environment. This project tries to model the reorganisation of the charge distribution by atomic polarisation forces in three different ways:
  • The fluctuating charge model changes the atomic partial charges as a function of the molecular neighbourhood.
  • The induced-point-dipole method emulates the same effect by an auxiliary set of induced mathematical dipoles.
  • Drude oscillators work with physical dipoles which are represented by a pair of opposite auxiliary charges.
In a first project phase, we will evaluate the three models with respect to their efficiency, stability and reality in case of molecular ionic liquids. With the most appropriate model at hand we will interpret, analyse and decompose the experimental dielectric spectra for different cation-anion combinations. A special emphasis lies on the influence of the induced dipoles and their coupling with the translational and rovibrational components. The last project phase is dedicated to the interpretation of solvation dynamics of the model solute Coumarin as measured by the dynamics Stokes shift. Thereby, the mutual relation between dielectric properties and solvation phenomena will be investigated in detail. The parameter-free Voronoi tessellation will be used for the decomposition of various solvation properties into shell specific contributions. In this way, the range of the solute's influence on the solvent ionic liquids can be rationalised.

International collaborations

  • Prof. R. Buchner (University of Regensburg)
  • Prof. N. Ernsting (Humboldt University of Berlin)

Publications

Comparing induced point-dipoles and Drude oscillators
M. Schmollngruber, V. Lesch, C. Schroeder, A. Heuer, O. Steinhauser, PHYSICAL CHEMISTRY CHEMICAL PHYSICS (2014), ASAP
Transport and dielectric properties of water and the influence of coarse-graining: Comparing BMW, SPC/E, and TIP3P models
Daniel Braun, Stefan Boresch, and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 140(6):064107 (2014)
Polarization effects on the solvation dynamics of coumarin C153 in ionic liquids: Components and their cross-correlations
Michael Schmollngruber, Christian Schroeder, and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 138(20):204504 (2013)
The effect of Thole functions on the simulation of ionic liquids with point induced dipoles at various densities
Thomas Taylor, Michael Schmollngruber, Christian Schroeder, and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 138(20):204119 (2013)
Communication: Solvation and dielectric response in ionic liquids-Conductivity extension of the continuum model
X. -x. Zhang, C. Schroeder, and N. P. Ernsting, JOURNAL OF CHEMICAL PHYSICS, 138(11):111102 (2013)
Polarisabilities of alkylimidazolium ionic liquids
Katharina Bica, Maggel Deetlefs, Christian Schroeder, and Kenneth r. Seddon, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 15(8):2703 (2013)
From Short-Range to Long-Range Intermolecular NOEs in Ionic Liquids: Frequency Does Matter
Sonja Gabl, Othmar Steinhauser, and Hermann Weingaertner, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 52(35):9242 (2013)
Computational studies of ionic liquids: Size does matter and time too
Sonja Gabl, Christian Schroeder, and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 137(9):094501 (2012)
Comparing reduced partial charge models with polarizable simulations of ionic liquids
Christian Schroeder, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 14(9):3089 (2012)
Imprint: (as stipulated by austrian law, MedienG 2005): O. Steinhauser / S. Boresch, Institut für Computergestützte Biologische Chemie, Währinger Strasse 17, 1090 Wien, Austria