Peripheral Templation-Modulated Interconversion between an A₄ L₆ Tetrahedral Anion Cage and A₂ L₃ Triple Helicate...

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Anion-coordination cages are of interest for molecular recognition and encapsulation.
• Controlling the assembly and disassembly of supramolecular structures is a key challenge.
• Ligand design is crucial for directing the formation of specific cage architectures.

Purpose of the Study:

• To construct and characterize a novel A4L6 tetrahedral cage based on anion coordination.
• To investigate the reversible interconversion between the A4L6 cage and an A2L3 triple helicate.
• To explore the use of peripheral templation for stabilizing the tetrahedral structure and creating an 'empty' cage for guest capture.

Main Methods:

• Synthesis of a C2-symmetric bis-bis(urea) ligand.
• Anion-templated self-assembly with phosphate.
• Spectroscopic and crystallographic analysis to determine structures.
• Investigation of stimuli-responsive behavior (template, concentration, solvent).
• Demonstration of guest capture and release using choline and acetylcholine.

Main Results:

• Successful construction of an anion-coordination-based A4L6 tetrahedral cage.
• Observed reversible interconversion between the A4L6 cage and an A2L3 triple helicate.
• Identified critical role of peripheral templation in stabilizing the tetrahedral cage.
• Assembled an 'empty' A4L6 cage capable of controlled guest binding.
• Demonstrated selective capture and release of choline and acetylcholine.

Conclusions:

• A novel anion-coordination-based A4L6 tetrahedral cage was successfully synthesized and characterized.
• Peripheral templation is a key strategy for stabilizing complex supramolecular architectures.
• The developed 'empty' cage offers a platform for stimuli-responsive capture and release of biologically relevant molecules.
• This work advances the design principles for dynamic and functional supramolecular cages.