Self-assembly, interlocking, interconversion and anion-binding catalysis in phenoxazine-based Pd₂L₄ and Pd₄L₈...

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Self-assembled coordination cages, particularly Pd2L4-type structures, often exhibit interpenetration.
• The precise mechanism governing cage interpenetration remains poorly understood.
• Controlling cage assembly and interpenetration is crucial for developing advanced functional materials.

Purpose of the Study:

• To synthesize and characterize phenoxazine-based monomeric (1) and interlocked dimeric (2) coordination cages.
• To investigate the solvent-mediated interconversion between the monomeric and dimeric cage forms.
• To elucidate the role of solvent and anions in templating cage assembly and interpenetration.

Main Methods:

• Synthesis of phenoxazine-based coordination cages.
• Single-crystal X-ray diffraction for structural analysis.
• Solvent-dependent self-assembly and interconversion studies.
• Anion binding and catalytic activity assessment.

Main Results:

• Successfully synthesized and isolated both monomeric cage 1 and dimeric cage 2.
• Demonstrated solvent-controlled interconversion between monomeric and dimeric cages.
• Identified specific solvent properties (coordinating strength) that drive the monomeric-to-dimeric and dimeric-to-monomeric transformations.
• Observed chloride anions templating interpenetration, suggesting a catalytic role for cage 2 in C-Cl bond cleavage.

Conclusions:

• The interconversion between monomeric and dimeric coordination cages is thermodynamically driven by solvent properties.
• Solvent choice is critical for controlling the self-assembly outcome, enabling isolation of specific cage architectures.
• The dimeric cage exhibits anion-binding capabilities and can potentially act as a catalyst in anion-templated reactions.