A molecular dynamics simulations study on the behavior of liquid N-methylacetamide in presence of NaCl: Structure, dynamics and H-bond properties

Abstract

The solvation structure, dynamics and hydrogen bond properties of NaCl solutions of liquid N-methylacetamide (NMA) are calculated at 313 K with varying concentrations by using classical molecular dynamics simulations. We have considered concentration range from 0 to 0.37 M NaCl solution in liquid NMA, to investigate the behavior of > C=O?H-N bond environments in presence salt. It is found that the addition of a small amount of NaCl facilitates the structural breaking of NMA, which decreases the number of hydrogen-bonds per NMA molecule and showing that the stability of hydrogen-bond decreases with ion concentrations. The self-diffusion coefficient of ions is found to be decreased with salt concentration and have an excellent agreement with experimental observation. The orientational relaxation times of liquid NMA show slower dynamics with increasing salt concentrations due to additional ion atmospheric friction. The residence time of NMA around ions and hydrogen-bond structural relaxation times of NMA in these solutions are also calculated. � 2012 Elsevier B.V. All rights reserved.