[5]Cumulene Bridged Tri(9-anthryl)Methyl Dimer.

Area of Science:

• Organic Chemistry
• Materials Science
• Solid-State Chemistry

Background:

• Stable radical frameworks are crucial for advanced materials.
• Controlling radical spin states with external stimuli remains a challenge.

Purpose of the Study:

• To design and synthesize a novel stable radical dimer for 2D frameworks.
• To investigate the spin-spin interactions and stability of the radical dimer.
• To explore the modulation of radical spin states via mechanical stimuli.

Main Methods:

• Synthesis of a diacetylene-bridged tri(9-anthryl)methyl (TAntM) radical dimer.
• X-ray crystallographic analysis to determine molecular structure and interactions.
• Variable-temperature 1H-NMR spectroscopy to study thermal spin state transitions.
• Solid-state mechanical grinding to induce structural and spin state changes.

Main Results:

• The TAntM radical dimer exhibits strong spin-spin interaction through the diacetylene linker, forming a stable closed-shell [5]cumulene structure.
• High-temperature NMR revealed signal broadening, indicating the presence of metastable triplet radical species.
• Mechanical grinding partially altered the radical species, suggesting reactivity and potential for external stimuli-induced changes.

Conclusions:

• A stable radical dimer with potential for 2D framework construction was successfully synthesized.
• The diacetylene linker facilitates significant spin-spin interactions, stabilizing the radical in a closed-shell form.
• Mechanical grinding demonstrates a pathway for external stimuli-responsive spin-state modulation in radical materials.