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Acid‐Regulated Switching of Metal Cation and Anion Guest Binding in Halogen‐Bonding Rotaxanes
Author(s) -
Li Xiaoxiong,
Lim Jason Y. C.,
Beer Paul D.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803902
Subject(s) - rotaxane , chemistry , hydrogen bond , halogen bond , anthracene , affinities , halide , metal , metal ions in aqueous solution , fluorescence , stereochemistry , binding site , supramolecular chemistry , aqueous solution , binding pocket , halogen , photochemistry , crystallography , molecule , inorganic chemistry , organic chemistry , crystal structure , physics , biochemistry , alkyl , quantum mechanics
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.