Using host−guest chemistries in a biphasic system, a novel supramolecular nanoparticle surfactant (s-NPS) with redox-responsiveness is presented to structure liquids. The in situ assembly/jamming and disassembly/unjamming of s-NPSs at the oil−water interface are reversibly controlled by a switchable redox process, imparting a nanoscale redox-responsiveness, affecting the assemblies on all length scales. "Smart" all-liquid constructs including structured emulsions and programmable liquid devices are easily prepared, showing promising applications in responsive delivery, release, and reaction systems.
Herein we disclose a new catalytic asymmetric approach for the synthesis of chiral α-amino ketones, which is particularly useful for the less accessible acyclic α-tertiary cases. By a protonation−amination sequence, our approach represents a rare asymmetric H−heteroatom bond insertion by αcarbonyl sulfonium ylides, an attractive surrogate of diazocarbonyls. The mild intermolecular C−N bond formation was catalyzed by chiral phosphoric acids with excellent efficiency and enantioselectivity. The products are precursors to other important chiral amine derivatives, including drug molecules and chiral ligands. The enantioselectivity was controlled by dynamic kinetic resolution in the amination step, rather than the initial protonation. This process opens up a new platform for the development of other related insertion reactions.
Synthesis of α-heterosubstituted ketones and related heterocyclic structures was achieved through sulfur mediated difunctionalization of internal alkynes in one pot.
Nanoparticle surfactants (NPSs) offer a powerful means to stabilize the oil‐water interface and construct all‐liquid devices with advanced functions. However, as the nanoparticle size decreases to molecular‐scale, the binding energy of the NPS to the interface reduces significantly, leading to a dynamic adsorption of NPS and “liquid‐like” state of the interfacial assemblies. Here, by using the host‐guest recognition between a water‐soluble small molecule, cucurbit[7]uril (CB[7]) and an oil‐soluble polymer ligand, methyl viologen‐terminated polystyrene, a supramolecular NPS model, termed CB[7] surfactant, is described. CB[7] surfactants form and assemble rapidly at the oil‐water interface, generating an elastic film with excellent mechanical properties. The binding energy of CB[7] surfactant to the interface is sufficiently high to hold it in a jammed state, transforming the interfacial assemblies from a “liquid‐like” to “solid‐like” state, enabling the structuring of liquids. With CB[7] surfactants as the emulsifier, O/W, W/O and O/W/O emulsions can be prepared in one step. Owing to the guest‐competitive responsiveness of CB[7] surfactants, the assembly/disassembly and jamming/unjamming of CB[7] surfactants can be well controlled, leading to the reconfiguration of all‐liquid constructs.
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