Regensburg 2016 – scientific programme

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BP: Fachverband Biologische Physik

BP 16: Posters - Computational Biophysics

BP 16.10: Poster

Monday, March 7, 2016, 17:30–19:30, Poster C

Salting out Constants of Aromatic Compounds - Experiment, Simulation and Kirkwood-Buff Theory — •Jakub Polak, Pavel Vrbka, and Jan Heyda — Department of Physical Chemistry, University of Chemistry and Technology, Prague, Czech Republic

Fluctuation theory of solutions, also called Kirkwood-Buff theory (KB), can be used to determine salting out constants of sparingly soluble molecules, from computer simulation data.

In this contribution, we have experimentally determined the limiting activity coefficients for large set of aromatic compounds (benzene, toluene, ethylbenzen and xylenes) in salt solutions (NaCl, Na2SO4, NaSCN). Following a recent simulation study of alkali halides salting-out effect on benzene (dx.doi.org/10.1021/jp5011154), we gained microscopic insight into the role of salts via all-atom molecular dynamics simulations.

The KB analysis of simulation data provide a solid evidence that the preferential binding of salt over water is weakly negative (i.e., salt is weakly depleted) for NaSCN, negative for NaCl, and very negative for Na2SO4, in accord with experimentally determined salting out constants.

The applicability of, in the community frequent, partitioning concepts, as well as the arbitrariness of the selection of 'reference' salt are discussed.