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

摘要

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^–.