THEORETICAL DETERMINATION OF PARTITION-COEFFICIENTS
THEORETICAL DETERMINATION OF PARTITION-COEFFICIENTS
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DOI：
10.1021/ja00036a009
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发表时间：
1992-05-06
影响因子：
15
通讯作者：
RICHARDS, WG
中科院分区：
文献类型：
--
作者：
ESSEX, JW;REYNOLDS, CA;RICHARDS, WG
自由能微扰法，在分子动力学框架内实施，已被用来计算在水和四氯化碳之间分配的甲醇，乙醇和丙醇之间的日志Ps的差异。计算结果与实验结果一致，在0.45 log P单位或约3 kJ mol-1。甲醇和乙醇之间log P的差异相对容易确定。然而，在扩展计算以包括更灵活的丙醇分子时遇到了困难。一个系统的参数变化进行了突出的原因，结果不佳，即失败的原子电荷，以提供一个很好的描述在所有构象的静电。这个问题被克服了，通过使用来自分子静电势（MEP）为每个构象，根据适当的Bolzmann人口加权的电荷。建议这些多构象MEP衍生的电荷将在许多其他应用中是有用的。
The free energy perturbation method, implemented within a molecular dynamics framework, has been used to calculate differences in log Ps between methanol, ethanol, and propanol partitioned between water and carbon tetrachloride. The calculated results agree with experiment to within 0.45 log P unit or about 3 kJ mol-1. The difference in log P between methanol and ethanol was determined relatively easily. However, difficulties were experienced in extending the calculations to include the more flexible propanol molecule. A systematic variation of parameters was performed which highlighted the reason for the poor results, namely, the failure of the atomic charges to give a good description of the electrostatics in all conformations. This problem was overcome by using charges derived from the molecular electrostatic potential (MEP) for each conformation, weighted according to the appropriate Bolzmann population. It is proposed that these multiple conformation MEP derived charges will be useful in many other applications.