Resolution of a Challenge for Solvation Modeling: Calculation of Dicarboxylic Acid Dissociation Constants Using Mixed Discrete鈥揅ontinuum Solvation Models

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• 作者：Aleksandr V. Marenich ; Wendu Ding ; Christopher J. Cramer ; Donald G. Truhlar
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：June 7, 2012
• 年：2012
• 卷：3
• 期：11
• 页码：1437-1442
• 全文大小：253K
• 年卷期：v.3,no.11(June 7, 2012)
• ISSN：1948-7185

文摘

First and second dissociation constants (pK_a values) of oxalic acid, malonic acid, and adipic acid were computed by using a number of theoretical protocols based on density functional theory and using both continuum solvation models and mixed discrete鈥揷ontinuum solvation models. We show that fully implicit solvation models (in which the entire solvent is represented by a dielectric continuum) fail badly for dicarboxylic acids with mean unsigned errors (averaged over six pK_a values) of 2.4鈥?.0 log units, depending on the particular implicit model used. The use of water鈥搒olute clusters and accounting for multiple conformations in solution significantly improve the performance of both generalized Born solvation models and models that solve the nonhomogeneous dielectric Poisson equation for bulk electrostatics. The four most successful models have mean unsigned errors of only 0.6鈥?.8 log units.

Keywords:

dicarboxylic acid; dielectric continuum; generalized Born; PCM; SM8; SM8AD; SMD; solvation model