The concentration effect on the ‘hydrophobic’ and ‘hydrophilic’ behaviour around DMSO in dilute aqueous DMSO solutions. A computer simulation study
Ricardo L. Manceraa, Michalis Chalarisb, 1 and Jannis Samios
, 
, b
a De Novo Pharmaceuticals Ltd., Compass House, Vision Park, Chivers Way, Histon, Cambridge CB4 9ZR, UK
b Laboratory of Physical Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis 157-71, Athens, Greece
Available online 21 October 2003.
We have carried out a molecular dynamics study of dimethyl sulfoxide (DMSO) in water at 298 K at two different densities by simulating two different concentrations: 0.055 and 0.19 mole fraction. We have found an enhancement in the structure of water, an effect that becomes more pronounced as the concentration of DMSO increases. At both concentrations there is a well-defined hydration structure around the oxygen atom of DMSO, which is able to establish strong hydrogen bonds with surrounding water molecules. An increase in the concentration of DMSO depletes the solution of bulk water molecules, reducing the number of hydrogen bonds that water can have in the immediate vicinity of DMSO but increasing the strength of the hydrogen bonds made between the oxygen atom of DMSO and water. There is clear evidence of ‘hydrophobic’ hydration around the methyl groups of DMSO, which is enhanced as the concentration of DMSO increases.
Author Keywords: Molecular dynamics; DMSO; Aqueous solutions; ‘Hydrophobic’ hydration
