Catenation and Aggregation of Multi-Cavity Coordination Cages

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Metal-mediated cages offer versatile platforms for molecular assembly.
• Designing cages with controllable structures and functions is a key challenge.
• Understanding self-assembly processes is crucial for developing new materials.

Purpose of the Study:

• To synthesize and characterize novel multi-cavity metal-mediated cages.
• To investigate the structural transformation of a palladium cage upon anion addition.
• To explore the self-assembly behavior and potential applications of these cages.

Main Methods:

• Synthesis of palladium(II) cages using bridging ligands.
• Characterization using NMR spectroscopy, mass spectrometry, and X-ray crystallography.
• Small-angle neutron scattering (SANS) for studying aggregation.
• Investigation of interactions with oligonucleotide double-strands.

Main Results:

• Successful synthesis and characterization of multiple metal-mediated cages.
• Quantitative conversion of a peanut-shaped cage to an interpenetrated dimer upon chloride addition, revealing a novel linear {[Pd-Cl-]5Pd} stack.
• Aggregation of the dimer into disc-like structures via solvophobic interactions.
• Demonstrated interaction of the cage with polyanionic oligonucleotide double-strands in water.

Conclusions:

• The study presents a new class of palladium cages with tunable structures.
• Chloride anions induce a unique structural transformation, forming an unprecedented palladium-chloride motif.
• The self-assembly and DNA-binding properties suggest potential applications in non-covalent DNA interactions.