Ion–Hydrocarbon and/or Ion–Ion Interactions: Direct and Reverse Hofmeister Effects in a Synthetic Host,Journal of the American Chemical Society

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Ion–Hydrocarbon and/or Ion–Ion Interactions: Direct and Reverse Hofmeister Effects in a Synthetic Host
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-03-13 , DOI: 10.1021/jacs.8b00196
Jacobs H Jordan ₁ , Corinne L D Gibb ₁ , Anthony Wishard ₁ , Thu Pham ₁ , Bruce C Gibb ₁

Affiliation

A combination of 1H NMR spectroscopy, DLS, and turbidity measurements reveal that polarizable anions engender both the Hofmeister and reverse Hofmeister effects in positand 2. Host 2 possesses two principal and distinctly different binding sites: a "soft" nonpolar pocket and a "hard" crown of ammonium cations. NMR spectroscopy reveals that anion affinity to both sites is comparable, with each site showing characteristic selectivities. NMR spectroscopy also reveals that anions competitively bind to the pocket and induce the Hofmeister effect in host-guest binding at very low concentrations (∼2 mM). Furthermore, the suite of techniques utilized demonstrates that anion binding to both sites leads to charge attenuation, aggregation, and finally precipitation (the reverse Hofmeister effect). Anion-induced precipitation generally correlated with affinity, and comparisons between the free host and its adamantane carboxylate (Ada-CO2-) complex reveals that the reverse Hofmeister effect is attenuated by blocking anion binding/charge attenuation at the nonpolar pocket.

中文翻译：

离子-碳氢化合物和/或离子-离子相互作用：合成主体中的直接和反向霍夫迈斯特效应

1H NMR 光谱、DLS 和浊度测量的组合表明，可极化阴离子在正位 2 中产生霍夫迈斯特效应和逆霍夫迈斯特效应。宿主 2 拥有两个主要且明显不同的结合位点：一个“软”非极性口袋和一个“硬”结合位点铵阳离子冠。核磁共振波谱显示，阴离子对两个位点的亲和力相当，每个位点都显示出特征选择性。核磁共振波谱还表明，阴离子竞争性地结合到口袋上，并在非常低的浓度（~2 mM）下诱导主客体结合中的霍夫迈斯特效应。此外，所使用的技术套件表明，阴离子与两个位点的结合会导致电荷衰减、聚集，并最终沉淀（反向霍夫迈斯特效应）。阴离子诱导的沉淀通常与亲和力相关，游离主体与其金刚烷羧酸盐 (Ada-CO2-) 复合物之间的比较表明，反向霍夫迈斯特效应通过阻止非极性口袋处的阴离子结合/电荷衰减而减弱。

更新日期：2018-03-13

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