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 1tBu achieved a binding affinity of 460 ± 50 M−1 for HSe− in 10% DMSO-d6/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−.