Expanding reversible chalcogenide binding: supramolecular receptors for the hydroselenide (HSe^-) anion

Synthetic supramolecular receptors have been widely used to study reversible solution binding of anions; however, few systems target highly-reactive species. In particular, the hydrochalcogenide anions hydrosulfide (HS^-) and hydroselenide (HSe^-) have been largely overlooked despite their critical roles in biological systems. Herein we present the first example of reversible HSe^- binding in two distinct synthetic supramolecular receptors, using hydrogen bonds from N-H and aromatic C-H moieties. The arylethynyl bisurea scaffold 1 achieved a binding affinity of 460 ± 50 M^-1 for HSe^- in 10% DMSO-d ₆/CD₃CN, whereas the tripodal-based receptor 2 achieved a binding affinity of 290 ± 50 M^-1 in CD₃CN. Association constants were also measured for HS^-, Cl^-, and Br^-, and both receptors favored binding of smaller, more basic anions. These studies contribute to a better understanding of chalcogenide hydrogen bonding and provide insights into further development of probes for the reversible binding, and potential quantification, of HSe^- and HS^-.