Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, Ankara, Turkey.
Nat Chem. 2022 Jan;14(1):40-45. doi: 10.1038/s41557-021-00805-z. Epub 2021 Nov 1.
Weakly hydrated anions help to solubilize hydrophobic macromolecules in aqueous solutions, but small molecules comprising the same chemical constituents precipitate out when exposed to these ions. Here, this apparent contradiction is resolved by systematically investigating the interactions of NaSCN with polyethylene oxide oligomers and polymers of varying molecular weight. A combination of spectroscopic and computational results reveals that SCN accumulates near the surface of polymers, but is excluded from monomers. This occurs because SCN preferentially binds to the centre of macromolecular chains, where the local water hydrogen-bonding network is disrupted. These findings suggest a link between ion-specific effects and theories addressing how hydrophobic hydration is modulated by the size and shape of a hydrophobic entity.
弱水化阴离子有助于在水溶液中溶解疏水分子，但当暴露于这些离子时，由相同化学组成的小分子会沉淀出来。在这里，通过系统研究 NaSCN 与聚氧化烯低聚物和不同分子量聚合物的相互作用，解决了这一明显的矛盾。光谱和计算结果的结合表明，SCN 聚集在聚合物表面附近，但被单体排斥。这是因为 SCN 优先与大分子链的中心结合，在那里局部水分子氢键网络被破坏。这些发现表明离子特异性效应与解释疏水水合如何被疏水实体的大小和形状调节的理论之间存在联系。
