An Air-Stable Carbon-Centered Triradical with a Well-Addressable Quartet Ground State

Area of Science:

• Organic Chemistry
• Quantum Materials Science
• Molecular Magnetism

Background:

• Organic polyradicals are crucial for spin manipulation in quantum devices.
• High reactivity and low stability of conventional polyradicals hinder their application.
• A stable, high-spin organic material is needed for advanced quantum technologies.

Purpose of the Study:

• To synthesize and characterize a highly stable organic carbon-centered triradical (TR) with a quartet ground state.
• To investigate the magnetic properties, including anisotropy and Zeeman splitting, of the TR.
• To demonstrate the potential for coherent spin manipulation using the TR.

Main Methods:

• Synthesis of a novel carbon-centered triradical (TR).
• X-ray crystallography for structural determination.
• SQUID magnetometry and Electron Paramagnetic Resonance (EPR) spectroscopy for magnetic characterization.
• Demonstration of selective Zeeman level excitation in frozen solution.

Main Results:

• Achieved a highly stable TR with a quartet ground state (ΔE_D-Q = 0.78 kcal/mol) and long half-life (∼90 days).
• Confirmed quartet ground state and high-spin nature through SQUID and EPR.
• Demonstrated unprecedented selective excitation between Zeeman levels without sample alignment.
• Observed millisecond spin-lattice relaxation and microsecond coherence time.

Conclusions:

• The developed TR exhibits exceptional stability and favorable magnetic properties for spin manipulation.
• Selective Zeeman level excitation demonstrates potential for coherent spin control.
• This stable polyradical serves as a promising multi-energy-level quantum information carrier for quantum devices.