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 t Bu achieved a binding affinity of 460 ± 50 M-1 for HSe- in 10% DMSO-d 6/CD3CN, whereas the tripodal-based receptor 2CF3 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-.