Molecular dynamics simulation of the hydration structure and hydrogen bonding behavior of phenol in aqueous solution

Abstract

Molecular dynamics simulations are carried out to study the hydration structures and hydrogen bonding properties of phenol in aqueous solution with infinite dilution for several temperatures ranging from 273 to 363K. The hydration structures of phenol are characterized by radial distribution functions and orientational ordering. There appears structured local distribution of water around phenol within the distance of 8Å. Two hydration shells are defined to characterize the local structure. The orientation distribution of the water in the first hydration shell shows more ordered local structure than that in the second hydration shell. Increasing temperature leads to the disruption of the local structure. We mainly focus on the analysis of the hydrogen bonding interaction between phenol hydroxyl and water. The hydrogen bonds are identified based on the geometric criterion, which is defined according to analysis of radial distribution function and angle distribution. A definition of hydrogen bonding state f(m, n) is proposed to characterize the hydrogen bonding structure of phenol in aqueous solution. Phenol in the hydrogen bonding state f(m, n) means that the phenol hydroxyl forms m hydrogen bonds as donor and n hydrogen bonds as acceptor. At the different temperatures, the phenol hydroxyl prefers to stay in the hydrogen bonding state f(1, 1). It is shown that the hydrogen bonding state f(1, n) takes the dominant role. Thus phenol is proven to be a good hydrogen bond donor than acceptor. These findings help to further understand the hydration structure and hydrogen bonding behavior of phenol in aqueous solution.