利用程序设计的溶剂排除法实现在Foldamer胶囊中耐极性的氯离子结合，这一成果由美国印第安纳大学Amar H. Flood小组经过不懈努力而取得。 相关论文于2021年2月17日发表于《美国化学会杂志》。

受溶剂排除原理的启发，课题组人员创建了一个序列定义的Foldmeric胶囊，其整体最小构象显示螺旋折叠状态，并预组织为1:1阴离子络合。高稳定性的折叠几何和它排除溶剂的能力得到固态和溶液相研究支持。

该胶囊在二氯甲烷(ε_r=9)到乙腈(ε_r?=36)的溶剂介电常数(ε_r)增加4倍的情况下仍能保持10⁵ M^-1的高溶解度；ΔG ～28 kJ mol^-1。此行为是反常的。更典型的溶剂依赖性行为表现为，在对照化合物（例如芳基三唑大环和五元组）中，Cl^–亲和力急剧下降，其溶剂暴露的结合腔可被电介质屏蔽。最后，二甲基亚砜通过假定的溶剂结合使foldamer变性，然后使foldamer的Cl^–亲和力降低至正常水平。

这种胶囊的设计展示了一种开发有效受体的新原型，这种受体可以在极性溶剂中工作，并有可能帮助管理水圈和生物圈中存在的亲水阴离子。

据了解，在广泛的溶液环境中持续的阴离子结合是一个关键的挑战，持续激励和要求在合成受体设计上的新策略的发展。虽然在低极性溶剂中的阴离子强结合已经成为常规，但它们在高极性溶剂中保持高亲和力的能力还没有达到自然界所设定的标准。在水溶液环境中，蛋白使用其二级和三级从水中分离出阴离子结合位点，定期地结合和运输阴离子。

附：英文原文

Title: Polarity-Tolerant Chloride Binding in Foldamer Capsules by Programmed Solvent-Exclusion

Author: Yun Liu, Fred C. Parks, Edward G. Sheetz, Chun-Hsing Chen, Amar H. Flood

Issue&Volume: February 17, 2021

Abstract: Persistent anion binding in a wide range of solution environments is a key challenge that continues to motivate and demand new strategies in synthetic receptor design. Though strong binding in low-polarity solvents has become routine, our ability to maintain high affinities in high-polarity solvents has not yet reached the standard set by nature. Anions are bound and transported regularly in aqueous environments by proteins that use secondary and tertiary structure to isolate anion binding sites from water. Inspired by this principle of solvent exclusion, we created a sequence-defined foldameric capsule whose global minimum conformation displays a helical folded state and is preorganized for 1:1 anion complexation. The high stability of the folded geometry and its ability to exclude solvent were supported by solid-state and solution phase studies. This capsule then withstood a 4-fold increase in solvent dielectric constant (εr) from dichloromethane (9) to acetonitrile (36) while maintaining a high and solvent-independent affinity of 105 M–1; ΔG ～ 28 kJ mol–1. This behavior is unusual. More typical of solvent-dependent behavior, Cl– affinities were seen to plummet in control compounds, such as aryl-triazole macrocycles and pentads, with their solvent-exposed binding cavities susceptible to dielectric screening. Finally, dimethyl sulfoxide denatures the foldamer by putative solvent binding, which then lowers the foldamer’s Cl– affinity to normal levels. The design of this capsule demonstrates a new prototype for the development of potent receptors that can operate in polar solvents and has the potential to help manage hydrophilic anions present in the hydrosphere and biosphere.

DOI: 10.1021/jacs.0c12562

Source: https://pubs.acs.org/doi/10.1021/jacs.0c12562