Pnictogen-Bond-Directed Self-Assembly of Sb and As Cages Enables Partitioning of Organic Reaction Media

Pnictogen bonding directs self-assembly of antimony- and arsenic-based thiolate cages in organic media, with the Sb system forming persistent reversed-bilayer vesicles capable of chemical compartmentalization. This is demonstrated using chemoswitchable fluorescent probes that selectively quench extravesicular species. In contrast, As analogues form dynamic, transient assemblies with diminished compartmentalization. Density functional theory calculations reveal reduced electrostatic potential and cooperativity in the As systems, consistent with weaker pnictogen bonding interactions. These results establish pnictogen identity as a key factor governing vesicle stability and demonstrate a potentially general strategy for probing compartmentalization in nonaqueous systems.