Folding of coordination polymers into double-stranded helical organization

Area of Science:

• Supramolecular Chemistry
• Coordination Polymers
• Materials Science

Background:

• Coordination polymers self-assemble into diverse supramolecular structures.
• The metal center's coordination geometry dictates the final structure.
• Bispyridine ligands are versatile building blocks for coordination polymers.

Purpose of the Study:

• To investigate the self-assembly of coordination polymers based on Pd II and Cu II metal ions.
• To understand how metal coordination geometry influences supramolecular architecture.
• To explore the formation of helical structures and their stability.

Main Methods:

• Complexation of a bent-shaped bispyridine ligand with Pd II and Cu II metal ions.
• Characterization of self-assembled supramolecular structures.
• Density functional theory (DFT) calculations for structure optimization.

Main Results:

• Pd II-based polymer self-assembled into a layer structure via trans-positioned bridging ligands.
• Cu II-based polymer formed a double-helical conformation driven by copper-chloride dimeric interactions.
• DFT calculations confirmed the energetic favorability and experimental consistency of the double-helical structure.

Conclusions:

• Metal-ligand bridging interactions are key to constructing stable double-stranded helical nanotubes.
• The coordination geometry of metal ions significantly controls supramolecular self-assembly.
• This work provides a strategy for designing novel helical nanostructures.