Solubility and Molecular Conformations of n-Alkane Chains in Water
Solubility and Molecular Conformations of n-Alkane Chains in Water
复制标题
DOI：
10.1021/jp811229q
复制
发表时间：
2009-05-07
影响因子：
3.3
通讯作者：
Panagiotopoulos, Athanassios Z.
中科院分区：
文献类型：
--
作者：
Ferguson, Andrew L.;Debenedetti, Pablo G.;Panagiotopoulos, Athanassios Z.
我们采用分子动力学模拟研究了正构烷烃链在水中的溶解度和分子构象。我们发现溶解度随着碳数的增加几乎呈指数下降，直到正二十烷（C-20），并且与实验非常吻合，直到正十二烷（C-12）。我们没有检测到竖琴休息的碳数溶解度的依赖性。链构象的自由能景观分析揭示了理想气体和溶剂化相景观之间的显着相似性，这表明溶剂化链构象主要是由理想气体统计驱动。我们没有发现比正二十烷（C-20）短的正烷烃链的疏水性崩溃的证据。溶剂的主要影响是出现的障碍的顺序k（B）T，不存在于理想气体中，之间的自由能盆地对应于紧凑和扩展链构象，和最扩展的构象不稳定。我们的研究结果对于势模型的非平凡修改具有鲁棒性，这表明自由能景观上不存在强溶剂效应对于相对短（
We employ molecular dynamics simulations to study the solubility and molecular conformations of n-alkane chains in water. We find nearly exponential decrease in solubility with carbon number up to n-eicosane (C-20), and excellent agreement with experiment up to n-dodecane (C-12). We detect no harp break in the dependence of the solubility upon carbon number. A free energy landscape analysis of the chain conformations reveals remarkable similarities between the ideal gas and solvated phase landscapes, suggesting that solvated chain conformations are driven primarily by ideal gas statistics. We find no evidence for hydrophobic collapse of n-alkane chains shorter than n-eicosane (C-20). The primary effect of the solvent is the appearance of a barrier on the order k(B)T, not present in the ideal gas, between the free energy basins corresponding to compact and extended chain conformations, and destabilization of the most extended conformations. Our findings are robust to nontrivial modification of the potential model, suggesting that the absence of strong solvent effects on the free energy landscapes is fundamental to relatively short (