Preferential solvation of glucose and talose in water-acetonitrile mixtures: a molecular dynamics simulation study

We have investigated the preferential solvation of four carbohydrates, namely alpha- and beta-glucose and alpha- and beta-talose, in mixtures of water and acetonitrile. The structure of the solvation shell, obtained by means of molecular dynamics simulation, has been analyzed using radial and spatial distribution functions. In agreement with available experimental data, water is found to preferentially solvate the sugars. The micro-heterogeneity of the mixture, with clusters of hydrogen-bonded water molecules and clusters of dipole-dipole interacting acetonitrile molecules, favours the solvation of the carbohydrates by the water clusters. This, in turn, causes a stronger intermolecular NOE of the alkyl sugar protons with water than with acetonitrile.