Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Korea.
Division of Chemical Engineering and Bioengineering, Kangwon National University, Chuncheon, Gangwon-do 24341, Korea.
Molecules. 2018 Nov 9;23(11):2927. doi: 10.3390/molecules23112927.
The precise description of solute-water interactions is essential to understand the chemo-physical nature in hydration processes. Such a hydration thermodynamics for various solutes has been explored by means of explicit or implicit solvation methods. Using the Poisson-Boltzmann solvation model, the implicit models are well designed to reasonably predict the hydration free energies of polar solutes. The implicit model, however, is known to have shortcomings in estimating those for non-polar aromatic compounds. To investigate a cause of error, we employed a novel systematic framework of quantum-mechanical/molecular-mechanical (QM/MM) coupling protocol in explicit solvation manner, termed DFT-CES, based on the grid-based mean-field treatment. With the aid of DFT-CES, we delved into multiple energy parts, thereby comparing DFT-CES and PB models component-by-component. By applying the modified PB model to estimate the hydration free energies of non-polar solutes, we find a possibility to improve the predictability of PB models. We expect that this study could shed light on providing an accurate route to study the hydration thermodynamics for various solute compounds.
准确描述溶剂-水相互作用对于理解水合过程中的化学物理性质至关重要。通过使用显式或隐式溶剂化方法，可以探索各种溶质的这种水合热力学。隐式模型通过泊松-玻尔兹曼溶剂化模型设计，可以合理地预测极性溶质的水合自由能。然而，隐式模型已知在估计非极性芳香族化合物的水合自由能方面存在缺点。为了探究误差的原因，我们采用了一种新的基于网格的平均场处理的量子力学/分子力学（QM/MM）耦合协议的显式溶剂化方法，称为 DFT-CES。借助 DFT-CES，我们深入研究了多个能量部分，从而逐个组件地比较了 DFT-CES 和 PB 模型。通过将改进的 PB 模型应用于非极性溶质的水合自由能估计，我们发现有可能提高 PB 模型的可预测性。我们期望这项研究能够为研究各种溶质化合物的水合热力学提供准确的途径。
