Photoresponsive receptors for binding and releasing anions

Abstract

Photoresponsive receptors allow users to modulate when and where molecular hosts can bind and release their targets. This capability was pioneered in biochemistry, trained on cations, and is only now emerging in the recognition chemistry of anions. This mini review outlines the five instances where anion receptors have been manipulated by light. Cylindrical, acyclic, and helical receptors have been integrated with azobenzenes, stiff‐stilbenes, and dithienylethenes to generate modest‐to‐moderate changes in the binding affinities for various halides and polyatomic anions. The central design requirement involves choosing the appropriate photoswitch such that the two photostates can define two different organizations of the receptor, thus, enabling one state to bind better than the other. This challenge underscores the importance of analyzing the possible conformations, complexes, and stoichiometries that may be accessible by host and guest as a means to identify structures that will successfully elicit a switching response. Copyright © 2012 John Wiley & Sons, Ltd.