Department of

Computational Biological Chemistry

FWF P19807: Simulation studies of ionic liquids

grant holderProf. O. Steinhauser
funding period06/2007 - 05/2012
project sum277 k €

Abstract

Ionic liquids (IL) offer a variety of physical properties that make them attractive replacements for traditional organic solvents. Because of their non-volatility, ILs have gained increased attention as ''Green Chemistry'' solvents in the past decade. Most of them are moisture-stable thus offering the opportunity to use IL/water mixtures as novel solvents. By varying the molar ratio of IL vs. water, the role of ILs as solvents/co-solvents can be studied systematically. Due to strong electrostatic interactions, pure ILs may be seen as an ionic network. Therefore, IL/water mixtures are characterized by the co-existence and competition of a hydrogen-bond and an ionic network. First experimental results for these fascinating binary networks exist, but systematic computer simulation studies have not been reported yet. Therefore, we plan intensive investigations of ILs as solvents/co-solvents by molecular dynamics simulation. Collective properties, such as viscosity, conductivity and dielectric constant provide a quantitative measure of the cooperativity of the underlying ionic/hydrogen bond networks. For example, the tight coupling of ion pairs results in a low static conductivity in pure ILs. In mixtures with water, however, the competition with and integration into the hydrogen bond network weakens ionic pairs and thus enhances the conductivity as well as it reduces the viscosity. In addition, the higher polarity of the additional water component leads to a dielectric increment. The potential of ILs (pure or in mixtures with water) as novel, benign solvents offers interesting applications in biomolecular solvation. This part of the project will be the most challenging one, because now three networks, the IL ionic network, the water hydrogen bond network and the internal network of the biomolecular solute co-exist and compete. The simulation and interpretation of such a complex triple network goes beyond current routine computational studies. We will follow a stepwise approach involving smaller biomolecular solutes. In detail, we will analyze three major aspects: (i) The structure and stability of the hydrogen bond network of the biomolecular solute, (ii) the structure of the solvent/co-solvent in the vicinity of the solute (iii) the dynamics of the solvent/co-solvent molecules, in particular their retardation as compared to the bulk. Altogether, the computational analysis of the collective behavior of ILs requires extremely good statistics. Thus, the simulation period to be covered has to be approximately 20 times longer than that of state of the art simulations.

International collaborations

  • Prof. H. Weingärtner (University of Bochum)

Publications

Hydrated Ionic Liquids with and without Solute: The Influence of Water Content and Protein Solutes
Michael Haberler, Christian Schroeder, and Othmar Steinhauser, JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 8(10):3911 (2012)
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)
Solvation studies of a zinc finger protein in hydrated ionic liquids
Michael Haberler, Christian Schroeder, and Othmar Steinhauser, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 13(15):6924 (2011)
On the influence of hydrated ionic liquids on the dynamical structure of model proteins: a computational study
Michael Haberler and Othmar Steinhauser, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 13(40):17994 (2011)
Simulating polarizable molecular ionic liquids with Drude oscillators
Christian Schroeder and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 133(15):154511 (2010)
Using fit functions in computational dielectric spectroscopy
Christian Schroeder and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 132(24):244109 (2010)
Global and local Voronoi analysis of solvation shells of proteins
Gregor Neumayr, Tibor Rudas, and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 133(8):084108 (2010)
Relaxation of Voronoi shells in hydrated molecular ionic liquids
G. Neumayr, C. Schroeder, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 131(17):174509 (2009)
On the dielectric conductivity of molecular ionic liquids
Christian Schroeder and Othmar Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 131(11):114504 (2009)
On the collective network of ionic liquid/water mixtures. III. Structural analysis of ionic liquids on the basis of Voronoi decomposition
C. Schroeder, G. Neumayr, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 130(19):194503 (2009)
On the collective network of ionic liquid/water mixtures. II. Decomposition and interpretation of dielectric spectra
C. Schroeder, J. Hunger, A. Stoppa, R. Buchner, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 129(18):184501 (2008)
The influence of electrostatic forces on the structure and dynamics of molecular ionic liquids
C. Schroeder and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 128(22):224503 (2008)
On the computation and contribution of conductivity in molecular ionic liquids
C. Schroeder, M. Haberler, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 128(13):134501 (2008)
On the collective network of ionic liquid/water mixtures. I. Orientational structure
C. Schroeder, T. Rudas, G. Neumayr, S. Benkner, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 127(23):234503 (2007)
Impact of anisotropy on the structure and dynamics of ionic liquids: A computational study of 1-butyl-3-methyl-imidazolium trifluoroacetate
C. Schroeder, T. Rudas, G. Neumayr, W. Gansterer, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 127(4):044505 (2007)
Collective rotational dynamics in ionic liquids: A computational and experimental study of 1-butyl-3-methyl-imidazolium tetrafluoroborate
C. Schroeder, C. Wakai, H. Weingartner, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 126(8):084511 (2007)
Simulation studies of ionic liquids: Orientational correlations and static dielectric properties
C. Schroeder, T. Rudas, and O. Steinhauser, JOURNAL OF CHEMICAL PHYSICS, 125(24):244506 (2006)
Imprint: (as stipulated by austrian law, MedienG 2005): O. Steinhauser / S. Boresch, Institut für Computergestützte Biologische Chemie, Währinger Strasse 17, 1090 Wien, Austria