A 4,4',4″-nitrilotriphenoxyl radical derived from Yang's biradical

Area of Science:

• Organic Chemistry
• Materials Science
• Physical Chemistry

Background:

• Phenoxyl radicals are crucial in various scientific fields due to their distinct electronic properties.
• Nitrogen-bridged polyphenoxyl radicals represent an underexplored class of organic open-shell systems.

Purpose of the Study:

• To synthesize and characterize a novel 4,4',4″-nitrilotriphenoxyl radical.
• To investigate the electronic structure, stability, and symmetry of the synthesized radical and its related closed-shell species.
• To establish a new molecular design for stable organic open-shell systems.

Main Methods:

• Synthesis of the target nitrilotriphenoxyl radical and its precursor.
• Spectroscopic and electrochemical characterization.
• Single-crystal X-ray diffraction.
• Computational chemistry methods (e.g., DFT) for electronic structure analysis.

Main Results:

• A new monoradical, 4,4',4″-nitrilotriphenoxyl radical (3), was successfully synthesized and characterized.
• Radical 3 exhibits an open-shell doublet ground state with delocalized unpaired electron density.
• The radical is metastable in solution, with a half-life of approximately 116 minutes, reverting to its closed-shell hydroxyl precursor (2).
• The precursor (2) and its deprotonated anionic form (4) display closed-shell singlet ground states and quinoidal character.
• Structural analysis revealed C3 symmetry for radical 3 and C2 symmetry for species 2 and 4.

Conclusions:

• The study provides fundamental insights into the electronic structures of nitrogen-bridged polyphenoxyl radicals.
• The findings establish a new platform for designing stable organic open-shell materials.
• The characterized radical and its derivatives offer potential for advanced applications in chemistry and materials science.