The discovery of molecules able to selectively bind to and signal the presence of anionic species is of interest from the perspective of potential applications in medicine, national security and environmental monitoring. The most commonly employed approach involves the design and synthesis of small-molecule hosts that interact with the anionic analyte through preorganized functional groups (for example, hydrogen bond donor groups).

In recent years, synthetic macromolecules have emerged as broadly applicable systems for anion recognition and sensing: the types of polymers employed in these applications are diverse in structure, and include organoboron- and organosilicon-based materials, metal-bound macromolecules, polycations, fluorescent polymers, and polyamides. These systems often benefit from unique effects that stem from their polymeric nature, including signal amplification, multivalency and cooperative behavior. 

With this in mind, Mark S. Taylor and co-workers (University of Toronto, Canada) have published new work highlighting the diversity of anion-responsive macromolecules that have been developed, with an emphasis on the unique effects that arise from incorporation of anion-binding moieties into polymeric systems.