Hyperporphyrinization-Enhanced Electron Transfer in Covalent Organic Frameworks for Metal-Free Photocatalytic C-H...

Area of Science:

• Materials Science
• Photocatalysis
• Organic Chemistry

Background:

• Covalent organic frameworks (COFs) face challenges in photosensitizer integration and charge transfer efficiency.
• Electron localization across linkages in COFs limits their photocatalytic performance.

Purpose of the Study:

• To overcome limitations in COF-based photocatalysts by developing a hyperporphyrinization strategy.
• To enhance charge transfer and photocatalytic activity through a novel COF structure.

Main Methods:

• Synthesized a novel hyperporphyrinic COF (HP-COF) using porphyrinic photosensitizers and bipyridine N-oxide moieties linked by imine bonds.
• Investigated linker-to-linker charge transfer (LLCT) by comparing HP-COF with an amide-linked analogue (NP-COF).
• Evaluated photocatalytic performance in metal-free C-H functionalization.

Main Results:

• HP-COF exhibits an unprecedented hyperporphyrin effect driven by LLCT across the imine linkage.
• LLCT enhances photooxidative potential, electron delocalization, and charge transport in HP-COF.
• HP-COF demonstrates superior photocatalytic activity and recyclability compared to NP-COF and homogeneous catalysts.

Conclusions:

• The hyperporphyrinization strategy effectively addresses limitations in COF-based photocatalysts.
• HP-COF shows significant potential for efficient and sustainable metal-free C-H functionalization.
• The developed COF material is stable and reusable for multiple catalytic cycles.