Cyanostilbenes as Selective Chloride Carriers Relying on CH-anion Interactions

Achieving selectivity is one of the challenges in developing anion receptors for transmembrane transport. This can be achieved through larger molecular designs that encapsulate the anion efficiently or by using alternative binding motifs instead of the most commonly used NH-based hydrogen bond donors. In this study, we present a series of small chloride receptors based on α-cyanostilbenes that use CH-based hydrogen bonds. By varying the substituents, we discovered that the compound containing four trifluoromethyl groups and a nitro group in addition to the two cyano groups exhibited the greatest affinity for chloride and the fastest chloride transport rates, surpassing the performance of reported triazole-based compound. Furthermore, this compound showed clear selectivity for transporting chloride over hydroxide, bicarbonate, and fluoride anions. The activity, selectivity, and deliverability of this compound make it a promising candidate for the treatment of chloride channelopathies.