Abstract

The diffusion and local structure of eight normal alkanols in 1-octanol at infinite dilution from 298 to 370 K have been investigated via molecular dynamics simulation. For short-chain n-alkanols, the simulated infinite dilute diffusion coefficients D₁₂ are in good agreement with the experimental data, while for long-chain n-alkanols, the simulated D₁₂ overestimate the experimental data. Meanwhile, the local structures are characterized by calculating the radial distribution functions, hydrogen bond, radius of gyration, and end-to-end distance. It is interesting that the average number of hydrogen bonds decreases as the chain length of n-alkanols increases from methanol to 1-heptanol, but unexpectedly, the average number of hydrogen bonds for 1-nonanol begins to increase. The simulation results demonstrate that a kind of intertwist effect through alkyl chain-chain interactions and caused by the molecular flexibility could explain the abnormal change of hydrogen bond number and the serious overestimation of simulated D₁₂ for long-chain n-alkanols.

中文翻译：

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1-辛醇中八种正烷醇的无限稀释扩散和局部结构的分子动力学模拟

摘要

通过分子动力学模拟研究了八种正链烷醇在 298 至 370 K 无限稀释下在 1-辛醇中的扩散和局部结构。对于短链正链烷醇，模拟的无限稀扩散系数D ₁₂与实验数据吻合良好，而对于长链正链烷醇，模拟的D ₁₂高估了实验数据。同时，通过计算径向分布函数、氢键、回转半径和端到端距离来表征局部结构。有趣的是，氢键的平均数量随着n的链长而减少-烷醇从甲醇增加到 1-庚醇，但出乎意料的是，1-壬醇的平均氢键数开始增加。模拟结果表明，一种通过烷基链-链相互作用和由分子柔性引起的交织效应可以解释氢键数的异常变化和长链正链烷醇模拟D ₁₂的严重高估。