Prof. Ranjit Biswas

Chemical, Biological and Macro-molecular Sciences,

S. N. Bose National Centre for Basic Sciences,

Kolkata 700106, India

E-mail: ranjit[at]bose.res.in

 

Brief Bio-sketch:

Dr. Ranjit Biswas is currently a senior professor in the Department of Chemical, Biological and Macro-molecular Sciences, S. N. Bose National Centre for Basic Sciences. His research interests includes developing microscopic understanding of interaction and dynamics in condensed phases via integrating theory, experiments and simulations. 

COMPOSITION DEPENDENT STRUCTURE AND DYNAMICS IN (IONIC LIQUID + CO-SOLVENT) BINARY MIXTURES: IMPACT OF THE CHEMICAL NATURE OF INTERACTION

 

Ionic liquids (ILs) are usually high viscous liquids, and this particular aspect poses a barrier for applications of pure ILs^1-2 as reaction media in many cases. That is why conventional organic solvents are often mixed with ILs to enhance the fluidity. Understanding properties of such binary mixtures is important for better applications of these mixtures. The chemical nature (non-polar, dipolar and quadrupolar) of the co-solvent is expected to modify the micro-structure and motional feature of the solution particles. However, such a study exploring the impact of the nature of interaction of the co-solvent with ionic liquid on the composition dependent structure and dynamics of IL+ co-solvent mixtures has not been conducted yet.

 

Here we have performed all-atom molecular dynamics simulations of three different types of binary mixtures of the IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM] [PF₆]), with the three different co-solvent molecules, hexane, acetonitrile and 1,4-dioxane. These co-solvent molecules (hexane, acetonitrile and 1,4-dioxane) are of comparable sizes but with differing polarities: non-polar, dipolar and quadrupolar. We have investigated these binary mixtures, covering the whole composition range from pure IL to pure solvent. We have investigated composition dependence of co-solvent location and clustering by calculating radial distribution functions (RDFs), void and neck distributions through Voronoi polyhedral analysis, and dynamic heterogeneity (DH) via computing non-Gaussian (NG), new non-Gaussian (NNG) parameters, single particle displacement distributions and four point dynamic susceptibilities.³ Our study reflects a significant dependence on co-solvent polarity of both dynamical and structural features in these IL+co-solvent mixtures.

 

 

References:

1.    Y. Kohno, H. Ohno, Chem. Commun., 2012, 48, 7119.

2.    J. Jacquemin, P. Husson, A. A. H. Padua, V. Majer, Green Chem., 2006, 8, 172.

3.    T. Pal, R. Biswas, J. Phys. Chem. B, 2015, 119, 15683-15695.