Engineered Binding Microenvironments in Halogen Bonding Polymers for Enhanced Anion Sensing

Mimicking nature’s biopolymeric protein architectures by designing hosts with binding cavities shielded from the bulk solvent environment is a promising approach to achieving anion recognition in competitive protic media. Accomplishing this, however, can be synthetically demanding. Herein we present a more synthetically tractable approach, by directly incorporating potent supramolecular anion recognition motifs into a polymeric scaffold, which can be engineered through a judicious selection of the co-monomer. This is demonstrated through a comprehensive analysis of anion recognition and sensing with redox-active, halogen bonding (XB) polymeric host systems. Notably, the polymeric hosts consistently outperform their monomeric analogues, with especially large halide anion binding enhancements by up to 50-fold observed in aqueous-organic solvent mixtures. These enhancements are rationalised by a consideration of generated low dielectric constant binding microenvironments from which there is appreciable solvent exclusion. This approach is applicable to a range of hosts and targets, enabling recognition and sensing in highly polar media, otherwise unattainable with the monomeric units alone.