Hydrophobic Collapse of Foldamer Capsules Drives Picomolar-Level Chloride Binding in Aqueous Acetonitrile Solutions
Hydrophobic Collapse of Foldamer Capsules Drives Picomolar-Level Chloride Binding in Aqueous Acetonitrile Solutions
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DOI：
10.1021/ja4074744
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发表时间：
2013-09-25
影响因子：
15
通讯作者：
Flood, Amar H.
中科院分区：
文献类型：
--
作者：
Hua, Yuran;Liu, Yun;Flood, Amar H.
水性介质是进行主体-客体化学的竞争性环境，特别是当客体高度带电时。虽然疏水结合是一种公认的方法，其中非极性口袋可以被设计为识别水中的非极性客人，但对于亲水性阴离子如氯离子，需要互补策略。在这里，我们提出了这样一种替代机制的证据，每天使用的蛋白质，但罕见的人工受体，其中疏水相互作用被证明是负责组织和稳定的芳基-三唑foldamer，以帮助从越来越多的水溶液中提取亲水性氯离子。其中，双螺旋复合物在掩埋类似于80%的π表面时获得稳定性，这错误地产生了用于氢键的有效的、排除溶剂的微环境。氯化物对双链体的总体亲和力在乙腈中的25%水v/v中是显著的（log beta（2）= 12.6），并且当水含量增加到50%时，其保持强（log beta（2）= 13.0）。随着非生物折叠体的可预测设计的增加，这种水辅助策略原则上可以用于结合其他亲水性客体。
Aqueous media are competitive environments in which to perform host-guest chemistry, particularly when the guest is highly charged. While hydrophobic binding is a recognized approach to this challenge in which apolar pockets can be designed to recognize apolar guests in water, complementary strategies are required for hydrophilic anions like chloride. Here, we present evidence of such an alternative mechanism, used everyday by proteins yet rare for artificial receptors, wherein hydrophobic interactions are shown to be responsible for organizing and stabilizing an aryl-triazole foldamer to help extract hydrophilic chloride ions from increasingly aqueous solutions. Therein, a double-helical complex gains stability upon burial of similar to 80% of the pi surfaces that simultaneousrly creates a potent, solvent-excluding microenvironment for hydrogen bonding. The chloride's overall affinity to the duplex is substantial in 25% water v/v in acetonitrile (log beta(2) = 12.6), and it remains strong (log beta(2) = 13.0) as the water content is increased to 50%. With the rise in predictable designs of abiological foldamers, this water-assisted strategy can, in principle, be utilized for binding other hydrophilic guests.