Effects of methanol on the hydrogen bonding structure and dynamics in aqueous N-methylacetamide solution

Abstract

The effect of methanol on the hydrogen bonding structure and dynamics in aqueous solution of N-methylacetamide (NMA) is investigated by classical molecular dynamics simulations. The modifications of structure and interaction between water and NMA in presence of methanol are calculated by different site–site radial distribution functions and average interaction energies between these species in the solution. It is observed that the methyl–methyl interaction between NMA and methanol prefers even at lower methanol concentration. The slower translational and rotational dynamics of NMA is observed in water–methanol mixtures as it is found for both water and methanol in the mixtures. The lifetime and structural-relaxation time of NMA–water and NMA–methanol hydrogen bonds show a strong increase with addition of methanol in the solution, whereas the change is not linearly dependent on concentration. It is also found that the lifetime of water–water and water–methanol hydrogen bond increases with increasing methanol concentration in the solution.