A Robust Heterometallic Pt₂Pd₂L₈ Double Cage Catenane

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Combining different metal ions in supramolecular structures can yield unique properties.
• Heterometallic mechanically interlocked architectures are rare and challenging to synthesize.
• Existing metal-organic cages often lack stability and selective binding capabilities.

Purpose of the Study:

• To report the first synthesis of a heterometallic, quadruply interlocked cage catenane.
• To demonstrate selective self-assembly of a specific Pt₂Pd₂L₈ isomer.
• To investigate the stability and anion-binding properties of the novel structure.

Main Methods:

• Metal-mediated self-assembly utilizing asymmetric ligands.
• Dynamic covalent chemistry for cage formation.
• Nuclear magnetic resonance (NMR) spectroscopy, trapped ion mobility spectrometry (TIMS), and single-crystal X-ray diffraction for structural characterization.

Main Results:

• Successful synthesis of a Pt₂Pd₂L₈ cage catenane with selective formation of a specific isomer.
• Pt(II) ions are located peripherally, while Pd(II) ions are interior and interlocked.
• The Pt₂Pd₂L₈ cage exhibits enhanced kinetic stability against disassembly by halide anions.
• High-affinity binding of halide anions by the Pt₂Pd₂L₈ cage.

Conclusions:

• The developed method allows for selective synthesis of complex heterometallic cages.
• The Pt₂Pd₂L₈ cage catenane offers superior kinetic stability compared to previous designs.
• The cage effectively sequesters halide anions from organic substrates, indicating potential applications in purification and sensing.