Effect of solvent, temperature, and pressure on hydrogen bonding and reorientation of water molecules

Abstract

On the basis of the study of the solvent, temperature, and pressure effects, we show how the NMR rotational correlation times τ 2R for a heavy water molecule in neat liquid and organic solvents are correlated with the strength of solute-solvent interactions, in particular, H bonds. At room temperature (30 °C), the correlation time is 2.1 ps in the random H-bond network in heavy water, whereas it is as small as 0.1 ps in such an apolar, hydrophobic solvent as carbon tetrachloride because of the absence of the H bonds between water molecules. Pressure distorts H bonds and accelerates the orientational motion of water molecules in neat liquid. Firm evidence is collected for the limitations of the Stokes-Einstein-Debye (SED) law in solution.