Reversible anion binding

Dickins, R. S. Gunnlaugsson, T. Parker, D. Peacock, R. D. Reversible anion binding in aqueous solution at a cationic heptacoordinate lanthanide centre selective bicarbonate sensing by time-delayed luminescence. Chem. Commun. 1998, 16, 1643-1644. 

SIGNALLING REVERSIBLE ANION BINDING IN AQUEOUS MEDIA... 

In a simplistic treatment, of course, an isolated metal ion could itself be viewed as a receptor for anions as it fulfills the basic criterion of reversible anion binding. The concept of an anion receptor, however, requires a reversal of this metal-centered viewpoint. For the purposes of this chapter, a receptor will be considered as a molecule designed for binding anions, which does so through a combination of bonding interactions (rather than through a single... 

Scheme 6.3 An example of reversible anion binding that induces a change in Ln hydration...

Pharmacology Bivalirudin directly inhibits thrombin by specifically binding to the catalytic site and to the anion-binding exosite of circulating and clot-bound thrombin. The binding of bivalirudin to thrombin is reversible. 

Carboxymethylation. It was found by Vallee and Li that one cysteine residue per subunit may be selectively carboxymethylated with iodoacetate.1405 Since this reaction causes deactivation of the enzyme, this cysteine residue, later identified as Cys-46,1406 was suggested to be at the active site. The deactivated carboxymethylated enzyme still binds NAD+. The carboxymethylation of this residue is preceded by a reversible binding of iodoacetate to the enzyme.1407 This observation has helped to identify an anion-binding site in the coenzymebinding domain, where the pyrophosphate group of the coenzyme binds. 

Anion binding is reversible and the precise interactions between receptor and anionic guest can be finely controlled by synthetic development of subtlety modified hydrogen-bond functional anion-binding cavities. This methodology for easy functionalization means these receptors have been modified to show unusual anion selectivities. They therefore have a great potential for incorporation into anion sensory, switchable, and functional devices. 

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