Anion-Controlled Structural Interconversion of Palladium Cages Enables Separations by Selective Guest Capture and...

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Chemical Engineering

Background:

• Self-assembled host-guest systems are crucial for molecular recognition.
• Controlled guest release from these systems often requires destructive stimuli.
• Developing reversible and selective guest binding/release mechanisms is a key challenge.

Purpose of the Study:

• To create interconverting metal-organic cages with distinct guest recognition properties.
• To demonstrate anion-triggered, reversible structural transformations for controlled guest release.
• To establish a supramolecular catch-and-release strategy for pharmaceutical purification.

Main Methods:

• Asymmetric ligand L self-assembly with palladium(II) to form two distinct metal-organic cages: Pd₄L₈(BF₄)₈ and Pd₆L₁₂(NTf₂)₁₂.
• Utilizing specific counter-anions to trigger reversible and quantitative cage interconversion.
• Employing anion-mediated structural transformations for orthogonal, multi-cycle guest binding and release.
• Designing and validating a closed-loop purification process for pharmaceutical isolation.

Main Results:

• Successfully synthesized interconverting palladium(II)-based metal-organic cages.
• Demonstrated clean, reversible, and quantitative structural transformations triggered by counter-anions.
• Showcased distinct guest recognition profiles for each cage.
• Achieved selective binding and release of different guest molecules under mild conditions.
• Isolated Darunavir from a complex mixture with high selectivity and efficiency using a closed-loop process.

Conclusions:

• Anion-mediated interconversion of metal-organic cages provides a powerful platform for orthogonal molecular separations.
• This supramolecular catch-and-release strategy enables selective and efficient purification of pharmaceutical compounds.
• The developed method offers a broadly applicable approach for advanced molecular separations and drug purification.