The road to aryl CH⋯anion binding was paved with good intentions: fundamental studies, host design, and historical perspectives in CH hydrogen bonding

Abstract

This feature article highlights recent approaches to anion recognition with a focus on aryl CH hydrogen bonds.

Hydrogen bond design principles

“…[32][33][34][35] Lippard et al demonstrated a remarkable F 2 C H…O hydrogen bonding motif 36 (Figure 4b), suggesting that C atoms with significant s character can form very strong C H…O interactions, and proposing that F 2 C H groups can be useful for replacing OH groups in medicinal applications of hydrogen bonding. Anion binding based on C H…anion interactions have gained increasing popularity, 37 and many receptors containing aryl C H hydrogen bonding interactions have been developed (see Figure 4c for some examples). [38][39][40] 2.2.2 | X H…π hydrogen bonding π-Bonds are electron rich and can replace F, O, or N atoms as hydrogen bond acceptors, giving rise to X H…π hydrogen bonding interactions (Figure 5a).…”

Carbazole sulfonamide-based macrocyclic receptors capable of selective complexation of fluoride ion

“…16,17 In addition, the utilization of aromatic CH group as hydrogen-bond donor for constructing anion receptors was hitherto less studied, 18,19 although they had some unique advantages over the conventional NH/OH hydrogen-bond donors including a remarkable resistance towards the deprotonation event 20 and a larger affinity towards soer anions in some cases. 21 In 2016, we synthesized 1,8-disulfonamidocarbazole-dipyrromethane Schiffbase macrocycle & its reduced derivative and evaluated their anion binding properties by UV-vis and 1 H NMR titration methods. 22 The results indicated that two macrocyclic receptors exhibited strong binding interactions (K a > 10 4 M À1 ) with uoride, acetate and dihydrogen phosphate ions over other anions in the highly competitive DMSO medium, but both macrocycles were poorly selective among these three anions.…”

A neutral porous organic polymer host for the recognition of anionic dyes in water

“…[22][23][24][25][26][27][28] Alternatively, receptors with charge-neutral donors including polar hydrogen (-NH, -OH) and more hydrophobic -CH, halogen, chalcogen, or p-bonds can also be used. [29][30][31][32][33][34][35][36][37][38][39][40][41] Even though polymers functionalized with receptors can be tailored to a specic anion, the receptor must be highly predesigned and can require complex synthetic routes. Polymers of this type can have limited utility for practical applications such as water purication or sensing, where scalability and ease of separation are important factors.…”