Hydration of Linear Alkanes is Governed by the Small Length-Scale Hydrophobic Effect
Hydration of Linear Alkanes is Governed by the Small Length-Scale Hydrophobic Effect
复制标题
直链烷烃的水合由小长度尺度的疏水效应控制
DOI：
10.1021/acs.jctc.2c00219
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发表时间：
2022
影响因子：
5.5
通讯作者：
Sharma, Sumit
中科院分区：
文献类型：
--
作者：
Singh, Himanshu;Sharma, Sumit
对于非极性球形溶质，疏水效应的长度尺度依赖性是很好理解的：对于小溶质（直径，d ≤ 0.8 nm），水合自由能是熵驱动的，而对于较大溶质（d ≤ 2 nm），它是熵驱动的。在各向异性分子如直链烷烃的情况下，疏水效应的性质还不清楚。本文采用分子模拟方法计算了直链烷烃从甲烷到十八烷的水合自由能和直径为3nm的球形癸烷液滴的水合自由能。我们发现，烷烃的水合自由能，无论其大小，是由小的长度尺度疏水效应。也就是说，与大的球形溶质的情况不同，直链烷烃的水合自由能是熵驱动的。
Length-scale dependence of the hydrophobic effect is well understood for apolar spherical solutes: for small solutes (diameter,d≲ 0.8 nm), the hydration free energy is entropically driven, while for larger solutes (d≳ 2 nm), it is enthalpically driven. The nature of the hydrophobic effect in the case of anisotropic molecules such as linear alkanes is not understood yet. In this work, we have calculated the hydration free energy of linear alkanes going from methane to octadecane and of a spherical decane droplet ofd≈ 3 nm using molecular simulations. We show that the hydration free energies of alkanes, irrespective of their size, are governed by the small length-scale hydrophobic effect. That is, unlike the case of large spherical solutes, the hydration free energies of linear alkanes are entropically driven.