Synergistic anion–π interactions in peptidomimetic polyethers

Anion-π interactions are crucial in various biological processes, such as enzyme catalysis and ion transport. Despite their significance, the exploitation of anion-π interactions in synthetic polymer systems remains underexplored. This study investigates anion-π interactions using chemically well-defined peptidomimetics guided by the composition of mussel foot proteins. Specifically, polyether-based polymers were designed utilizing two functional epoxide monomers-catechol acetonide glycidyl ether and 4,4-dimethyl-2-oxazoline glycidyl ether-to mimic the key amino acids 3,4-dihydroxyphenylalanine and aspartic acid, respectively. A surface forces apparatus was employed to study the anion-π interaction between the polymers, considering the effects of relative monomer composition and pH conditions. The maximum cohesion energy of 15.0 mJ/m² was observed at an equimolar monomer composition at pH 7. Incorporating a phenyl group instead of the catechol group and introducing competing anions confirmed the dominant role of anion-π interactions. This study highlights the significance of anion-π interactions, posing a high potential in the design and synthesis of functional materials.