Chen Bin, Siepmann J Ilja
Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA.
J Phys Chem B. 2006 Mar 2;110(8):3555-63. doi: 10.1021/jp0548164.
Octanol-water partition coefficients are extraordinarily successful for correlating and predicting numerous processes of pharmacological and environmental importance. The amphiphilic nature of the 1-octanol molecules allows the octanol phase to mimic the complexities of many different environments ranging from biomembranes to soil. However, the structural details of the octanol phase and whether its structure is altered upon water saturation are not yet fully understood. Configurational-bias Monte Carlo simulations in the Gibbs ensemble demonstrate that a diverse spectrum of hydrogen-bonded aggregates exists in dry and wet 1-octanol, and that water saturation substantially alters the 1-octanol environment from predominantly linear aggregates in dry octanol to larger cylindrical micelles with water cores in wet octanol. These simulation results are able to reconcile the conflicting views (chain-like or water-centered aggregates vs spherical micelles) of the 1-octanol structure inferred from thermodynamic arguments, spectroscopic measurements, and diffraction experiments. Calculated partition constants quantify the influence of water saturation on the solubility characteristics of the dry and wet octanol phases.
正辛醇 - 水分配系数在关联和预测众多具有药理学和环境重要性的过程方面极为成功。1 - 正辛醇分子的两亲性质使正辛醇相能够模拟从生物膜到土壤等许多不同环境的复杂性。然而，正辛醇相的结构细节以及其结构在水饱和时是否会发生改变尚未完全清楚。吉布斯系综中的构型偏置蒙特卡罗模拟表明，在干燥和湿润的1 - 正辛醇中存在多种氢键聚集体，并且水饱和会使1 - 正辛醇环境从干燥正辛醇中主要的线性聚集体显著改变为湿润正辛醇中带有水核的较大圆柱形胶束。这些模拟结果能够调和从热力学论证、光谱测量和衍射实验推断出的关于1 - 正辛醇结构的相互矛盾的观点（链状或水中心聚集体与球形胶束）。计算得到的分配常数量化了水饱和对干燥和湿润正辛醇相溶解度特性的影响。
