On the origin of the extremely different solubilities of polyethers in water
On the origin of the extremely different solubilities of polyethers in water
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DOI：
10.1038/s41467-019-10783-z
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发表时间：
2019-06-28
影响因子：
16.6
通讯作者：
Woutersen, Sander
中科院分区：
文献类型：
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作者：
Ensing, Bernd;Tiwari, Ambuj;Woutersen, Sander
聚醚的溶解度出人意料地违反直觉。最著名的例子是无限可溶的聚乙二醇（[- ch2 - ch2 -O-](n)）和完全不溶于水的聚甲醛（[- ch2 -O-](n)）之间的区别，这与人们从这些分子的碳氧比中所期望的完全相反。低聚聚醚和环聚醚也存在类似的异常。为了解决这个明显的谜团，我们使用飞秒振动和GHz介电光谱，并辅以从头计算和分子动力学模拟。我们发现水分子溶剂化聚醚的动力学根据它们的C/O组成有根本的不同。从头计算和模拟表明，这不是由于空间效应（通常认为），而是因为O原子上的部分电荷取决于它们被分离的C原子的数量。因此，我们的结果表明，诱导效应可以对水溶液的溶解度产生重大影响。
The solubilities of polyethers are surprisingly counter-intuitive. The best-known example is the difference between polyethylene glycol ([-CH2-CH2-O-](n)) which is infinitely soluble, and polyoxymethylene ([-CH2-O-](n)) which is completely insoluble in water, exactly the opposite of what one expects from the C/O ratios of these molecules. Similar anomalies exist for oligomeric and cyclic polyethers. To solve this apparent mystery, we use femtosecond vibrational and GHz dielectric spectroscopy with complementary ab initio calculations and molecular dynamics simulations. We find that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition. The ab initio calculations and simulations show that this is not because of steric effects (as is commonly believed), but because the partial charge on the O atoms depends on the number of C atoms by which they are separated. Our results thus show that inductive effects can have a major impact on aqueous solubilities.