Node Flexibility Unlocks Structural Adaptability and Guest Versatility of Anionocages

Area of Science:

• Supramolecular Chemistry
• Nanotechnology
• Materials Science

Background:

• Anionocages are promising host molecules due to their nodal flexibility, mimicking protein self-assembly and host-guest chemistry.
• Challenges in constructing large internal cavities have limited the application of anionocages.

Purpose of the Study:

• To develop an effective strategy for enhancing node flexibility in anionocages.
• To improve structural adaptability and guest encapsulation versatility of anionocages.
• To create anionocages capable of encapsulating guests of unprecedented size.

Main Methods:

• Utilizing anion coordination between a C3-symmetric tris-urea ligand (L) and an organophosphate (A) to generate flexible nodes.
• Employing crystal structure analysis to identify distinct anionocage architectures (tetrahedron, trigonal antiprism, octahedron).
• Investigating solution-phase interconversions among anionocages by modulating guest template, A/L ratio, and concentration.

Main Results:

• Formation of three geometrically distinct anionocages (A4L4, A6L6, A6L8) with cavity sizes ranging from 0.208 to 1.320 nm³.
• Demonstration of controlled interconversions among anionocages in solution.
• Successful encapsulation of the luminescent metal complex [Ru(bpy)3]2+, leading to enhanced quantum yield and lifetime.
• Induction of circularly polarized luminescence in racemic [Ru(bpy)3]2+ via chirality transfer using a chiral-anion-directed octahedral cage.

Conclusions:

• Enhanced node flexibility is an effective strategy for creating anionocages with improved structural adaptability and guest encapsulation versatility.
• The developed anionocages can encapsulate guests of unprecedented size and exhibit tunable interconversions.
• These anionocages show potential for applications in luminescence enhancement and chiral sensing through chirality transfer.