On the properties of aqueous amide solutions through classical molecular dynamics simulations

The structure and dynamics of infinitely diluted aqueous amide solutions is studied for 13 compounds in the NVT ensemble using classical molecular dynamics simulations. The aim of this work is to provide valuable insights into the effect of amides on liquid water properties in order to understand the amides role in the kinetic inhibition of clathrate hydrate formation in natural gas mixtures. The OPLS-AA forcefield is used to describe the amides, with parameters obtained through fitting of computed B3LYP/6-311++g^{* *} data when not available in the literature, and the SPC-E model is applied for water molecules. Structural properties of the solutions are analyzed via calculated radial distribution functions and dynamic properties are studied with the computed mean square displacements and velocity autocorrelation functions. Most of the studied compounds show a remarkable structuring effect on the surrounding water with strong interactions resulting from hydrogen bonding between solute and solvent molecules. Hydrophobic and hydrophilic synergistic effects influence the amide–water interaction and the properties of the water solvation shells around amides.