Selective Recognition of Chloride by a 24‐Membered Macrocyclic Host with a Hydrophobic Methylenepyrene Substituent

• Published in: European journal of organic chemistry 2020-08, Vol.2020 (29), p.4528-4533
• Main Authors: Dąbrowa, Kajetan, Lindner, Marcin, Wasiłek, Sylwia, Jurczak, Janusz
• Format: Article
• Language: English
• Subjects: Anion recognition; anti‐Hofmeister anion selectivity; Carboxylates; Chloride selective; Chlorides; Hydrophobicity; Macrocyclic receptors; Unclosed cryptand
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202000662

A structure‐guided design, synthesis, and characterization of neutral unclosed cryptand functionalized with a bulky and hydrophobic 1‐methylene‐pyrene substituent is described. The host selectively binds spherical chloride (Cl–) over bigger and more basic carboxylates (MeCO2–, PhCO2–) and dihydrogenphosphate (H2PO4–) in a competitive [D6]DMSO + 0.5 % H2O solvent mixture. The capture of chloride is accompanied by formation of sandwich‐type complex stabilized by π–π and CH–π interactions. Step‐wise addition of MeOH triggers release of the cargo in a controllable manner. Structure‐guided optimization of existing macrocyclic platform for anions allows synthesis of novel neutral receptor with extraordinary anti‐Hofmeister type selectivity for chloride. A drawing discloses X‐ray structure of the free receptor and its DFT‐calculated complex with chloride. The hydrophobic interactions are crucial for achieving selectivity for this spherical guest. The capture and release of cargo is controlled by the hydrogen‐bonding power of solvent in a controllable manner.