Mechanically stabilized tetrathiafulvalene radical dimers

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Electrochemistry

Background:

• Donor-acceptor [3]catenanes, featuring a tetracationic molecular square and π-electron rich macrocycles, were synthesized.
• These mechanically interlocked molecules serve as platforms for studying intermolecular interactions.
• Tetrathiafulvalene (TTF) radical dimers are of interest due to their unique electronic properties.

Purpose of the Study:

• To investigate the formation and stability of TTF radical dimers within a [3]catenane molecular flask.
• To explore the influence of secondary binding motifs on TTF radical dimer formation.
• To understand the fundamental interactions governing TTF radical dimer assembly.

Main Methods:

• Synthesis of two distinct donor-acceptor [3]catenanes.
• Redox control using cyclic voltammetry and spectroelectrochemistry.
• Characterization via UV-vis-NIR, EPR spectroscopies, and X-ray diffraction.
• Computational support using DFT calculations.

Main Results:

• The mechanically interlocked structure of [3]catenanes facilitates redox-controlled formation of TTF radical dimers.
• Stability of TTF radical-cation dimers can be tuned by modifying the macrocyclic components.
• Replacing 1,5-dioxynaphthalene (DNP) with a butadiyne group increased dimer distribution from 60% to 100%.

Conclusions:

• [3]catenanes provide an effective molecular flask for detailed study of TTF radical dimer interactions.
• Molecular design offers a route to control the stability and formation of TTF radical dimers.
• This work advances the fundamental understanding of radical-cation dimer interactions in confined environments.