Acid‐Regulated Switching of Metal Cation and Anion Guest Binding in Halogen‐Bonding Rotaxanes. Issue 67 (8th November 2018)

• Record Type: Journal Article
• Authors: Li, Xiaoxiong; Lim, Jason Y. C.; Beer, Paul D.
• Is Part Of: Chemistry. Volume 24:Issue 67(2018)
• Page Start: 17788
• Page End: 17795
• Publication Date: 2018-11-08
• Subjects: anion recognition -- halogen bonding -- orthosteric regulation -- rotaxane -- transition metals; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201803902
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The ability of natural enzymes to regulate their guest binding affinities and preferences through the use of co‐ligands which alter the features of the binding site is fundamental to biological homeostatic control. Herein, the rarely exploited orthosteric control of guest binding is demonstrated using neutral halogen bonding [2]rotaxanes, in which a chemical stimulus (acid) interacting with the interlocked host binding site switches the host's native guest preference from metal cations to anions. When neutral, the rotaxanes exhibit pronounced transition metal cation affinity and comparatively weak anion binding properties. However, the addition of acid attenuates the rotaxanes' ability to coordinate cations, while concurrently enabling strong binding of halides through charge assisted halogen bonding and hydrogen bonding interactions in competitive aqueous solvent media. The appendage of a fluorescent anthracene reporter group to the rotaxane framework also enables diagnostic sensory responses to cation/anion binding. Abstract : Host–guest binding : By virtue of their novel antagonistic Lewis basic triazole‐secondary amine and Lewis acidic halogen bonding bis‐iodotriazole functional motifs, mechanically bonded interlocked rotaxane hosts are capable of acid‐triggered switching of metal cation and anion guest binding behaviour.