Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Phys Chem Chem Phys. 2011 Feb 21;13(7):2748-57. doi: 10.1039/c0cp01701a. Epub 2010 Dec 10.
We measure the solvation free energy, Δμ*, for hard spheres and Lennard-Jones particles in a number of artificial liquids made from modified water models. These liquids have reduced hydrogen bond strengths or altered bond angles. By measuring Δμ* for a number of state points at P = 1 bar and different temperatures, we obtain solvation entropies and enthalpies, which are related to the temperature dependence of the solubilities. By resolving the solvation entropy into the sum of the direct solute-solvent interaction and a term depending on the solvent reorganisation enthalpy we show that, although the hydrophobic effect in water at 300 K arises mainly from the small molecular size, its temperature dependence is anomalously low because the reorganisation enthalpy of liquid water is unusually small. We attribute this to the strong tetrahedral network which results from both the molecular geometry and the hydrogen bond strength.
我们测量了硬球和 Lennard-Jones 粒子在一些由改良水模型制成的人工液体中的溶剂化自由能Δμ*。这些液体的氢键强度降低或键角改变。通过在 P = 1 bar 和不同温度下测量多个状态点的Δμ*，我们获得了溶剂化焓和熵，它们与溶解度的温度依赖性有关。通过将溶剂化熵分解为溶质-溶剂直接相互作用项和依赖于溶剂重组焓的项，我们表明，尽管 300 K 下水的疏水作用主要来自于分子尺寸小，但它的温度依赖性异常低，因为液态水的重组焓异常小。我们将其归因于分子几何形状和氢键强度导致的强四面体网络。
