Redox-Induced Structural Rearrangement in an M₈L₂ Self-Assembly

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Coordination cages are dynamic, adaptable architectures sensitive to external stimuli.
• The metal-ligand bond's reversible nature allows for structural transformations.

Purpose of the Study:

• To synthesize a redox-responsive discrete coordination cage.
• To investigate the structural changes induced by redox stimuli.

Main Methods:

• Coordination-driven self-assembly of bis(ruthenium(II)) complexes (Ru2) and tetrapyridyl ligands (L).
• Ligand L is based on the redox-sensitive π-extended tetrathiafulvalene (exTTF) framework.
• Characterization of the initial and oxidized cage structures.

Main Results:

• A discrete (Ru2)4L2 architecture with a twisted configuration was successfully prepared.
• Oxidation of the exTTF ligand induced a structural transformation to a (Ru2)4L(ox)2 structure.
• The oxidized structure features spatially separated ligands in a face-to-face arrangement due to redox-induced changes and electrostatic repulsion.
• The structural transformation is fully reversible upon chemical reduction.

Conclusions:

• Demonstrated the successful synthesis of a redox-responsive coordination cage.
• Established a link between the redox state of the exTTF ligand and the cage's supramolecular structure.
• Highlighted the potential of such dynamic architectures for responsive materials.