An explicit solvent quantum chemistry study on the water environment influence on the interactions of fluoride with phenol

Abstract

The phenol complexes with fluoride in water solution were analyzed for different F⋯O separation distances ranging from 2.6 A up to 4.0 A with 0.2 A intervals. The quenching molecular dynamics runs were followed by hybrid quantum mechanics–molecular mechanics (QM–MM) geometry optimization at B3LYP/6–311+G** level. The analysis of MD trajectories allowed for detailed characteristics of hydration patterns and mobility of fluoride and phenol hydroxyl group. The explicit solvent molecules taken into account in QM–MM studies impose solute geometry changes according to fluctuations of the structure of its nearest neighborhood. Hence, fluctuations of HOMA (harmonic oscillator model of aromaticity index) values were observed corresponding to different conformations of water molecules around the solute. However, the screening role of the water molecules was noticed, which reduces the influence of the fluoride compared with the gas phase. Similarly as in vapor state, also in water solution the formation of hydrogen bond between the fluoride and the hydroxyl group of phenol is energetically favorable.