Carboxylate and dicarboxylate species are of significant interest due to their myriad roles in biology, industry, pharmacology, and as environmental contaminants.1 However, despite recent advances in receptor development, the selective recognition and sensing of many of these species—particularly in aqueous environments—remains elusive.1
The guanidinium motif has been identified as a highly effective motif for binding to carboxylate species.2 Guanidinium groups provide a combination of highly directional hydrogen bond donors with geometric complementarity to carboxylates, and a cationic charge that increases anion binding affinities and aqueous solubility.3 However, despite these characteristics, there are limited reports of macrocyclic guanidinium anion receptors in the literature.4,5 In this project, we present a modular synthesis of macrocyclic acyl guanidine and guanidinium receptors, and explore the effect of macrocyclization on the affinity and selectivity towards biologically relevant dicarboxylates and other anions.