Proton-shared hydrogen bond: Promoting generation of novel triradicals, and serving as phosphorescent and magnetic switch

• New diarylmethyl monoradicals were facilely synthesized.
• Proton-shared hydrogen bond induces diarylmethyl triradical crystals.
• Triradicals and monoradicals reveal various photophysical and magnetic properties.
• Phosphorescent “on/off” switch stimulated by acid and base.
• Proton-shared hydrogen bond serves as a magnetic switch.

Stable organic radicals have many essential and unique applications in chemistry, biology and materials. In order to probe new radical materials, we report herein a novel type of solid-state stable diarylmethyl monoradicals, which were synthesized via facile “one-pot” approach. The monoradicals can be easily converted to solid-state stable diarylmethyl triradicals promoted by unusual and symmetric proton-shared hydrogen bond. Diarylmethyl triradicals reveal higher ambient phosphorescent quantum yield and enhanced near-infrared absorption. Moreover, switchable phosphorescent and magnetic transformation between triradicals and monoradicals controlled by proton-shared hydrogen bond avails to develop switch materials. Unprecedentedly, the proton-shared hydrogen bond serves as a phosphorescent and magnetic switch. The present work provides a new access to synthesize stable diaryl-methyl (-alkyl) radicals and develop new switchable materials.

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