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

Abstract

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^tBu achieved a binding affinity of 460 ± 50 M⁻¹ for HSe⁻ in 10% DMSO-d₆/CD₃CN, whereas the tripodal-based receptor 2^CF₃ 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⁻.