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)/CD(3)CN, whereas the tripodal-based receptor 2(CF(3)) achieved a binding affinity of 290 ± 50 M(–1) in CD(3)CN. 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(–).