Aromatic Chloride Catcher | Chemical & Engineering News
Latest News
Web Date: March 5, 2008

Aromatic Chloride Catcher

Macrocycle uses weak hydrogen bonds to sequester anion
Department: Science & Technology
Ion Grabber
Neutral macrocycle takes hold of a chloride ion (orange) in its central cavity.
8610news3
 
Ion Grabber
Neutral macrocycle takes hold of a chloride ion (orange) in its central cavity.

To grab hold of an anion, an organic host molecule usually uses strong hydrogen-bond donors, such as N–H bonds or C–H bonds adjacent to a cationic center. Now, chemists at Indiana University have shown that a neutral macrocycle equipped with only weak, aromatic C???H bonds can snatch up a chloride anion with an affinity akin to its stronger H–bonding brethren (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200704717).

Using "click chemistry" and other reactions, Amar H. Flood and Yongjun Li created a neutral macrocycle, wherein four phenyl rings alternate with four triazoles. Each of these eight rings donates one C–H bond for catching the chloride.

Flood and Li attribute the macrocycle's surprisingly good affinity for chloride ions to the triazole moieties' strong dipoles and to a central cavity that's a perfect size for the anion. The click chemistry-based synthesis makes it easy to create libraries of such macrocycles, Flood says, which could be used to sequester other anions.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

Leave A Comment

*Required to comment