Persistent Halogenated Perylenediimide Organic Radical Anions Orchestrating Three-Photon Energy Conversion and...

Area of Science:

• Organic Chemistry
• Photochemistry
• Materials Science

Background:

• Persistent radical ions are crucial for light harvesting but are often unstable.
• Developing stable radical ions for photocatalysis remains a significant challenge.

Purpose of the Study:

• To engineer a stable perylenediimide radical anion for advanced photocatalysis.
• To explore its potential in multi-photon processes and organic synthesis.

Main Methods:

• Halogen engineering of perylenediimide to create PDI-Br8•‒.
• Characterization of its stability, absorption, redox cycling, and excited-state lifetime.
• Application as a photocatalyst in a stereoselective coupling reaction.

Main Results:

• PDI-Br8•‒ exhibits exceptional air stability (>18 months) and broad visible light absorption.
• It demonstrates reversible two-electron redox cycling and a long excited-state lifetime (∼2 ns).
• Efficiently catalyzes the one-pot synthesis of (E)-enenitriles from alkynes, acrylonitrile, and bromotrihalomethanes at low loading.

Conclusions:

• Halogen substitution stabilizes the radical anion, enabling its use as a robust photocatalyst.
• This work presents a molecular design for multi-photon radical photochemistry.
• The developed radical unifies energy storage, charge transport, and synthetic reactivity.