Self-Assembly and Molecular Recognition by Synthetic Receptors at the Oil-Water Interface in Aqueous Microdroplets.

Aqueous microdroplets in a bulk fluorous oil medium confer unique behavior on self-folding water-soluble synthetic receptors (deep cavitands). The lipophilic, yet water-soluble cavitands self-assemble at the water-oil interface, coating the surface of the microdroplet rather than diffusing through the interior. By combining the receptors with indicator dyes that bind in the host cavity, simple optical detection of the molecular recognition event is possible, as is spatiotemporal monitoring of the receptors in the droplets. The interfacial self-assembly of the host-guest complex is driven by hydrophobic association between the individual cavitand molecules, and controlled molecular recognition of suitable guest molecules can be observed. By exploiting droplet merging experiments, the cavity-based and aggregative molecular recognition behaviors can be differentiated. The system provides a unique insight into supramolecular aggregation, interfacial behavior, and molecular recognition at water-oil interfaces.