A BOIMPY Dye Enables Multi-Photoinduced Electron Transfer Catalysis: Reaching Super-Reducing Properties

Area of Science:

• Organic Chemistry
• Photocatalysis
• Redox Chemistry

Background:

• Photoinduced electron transfer (PET) is a known method for generating radical intermediates.
• Consecutive photoinduced electron transfer (con-PET) utilizes two photons to create higher-energy species.
• Increased photon uptake generally enhances reductant potency.

Purpose of the Study:

• To introduce and explore the concept of multi-photoinduced electron transfer catalysis (multi-PET) involving more than two photons.
• To demonstrate the generation of a highly potent photoexcited dianionic super-reductant.
• To showcase the application of multi-PET in cleaving strong bonds and performing challenging reductions.

Main Methods:

• Utilizing photoinduced one-electron reductions of an organic dye.
• Employing 390 nm LEDs for multi-photon excitation.
• Conducting spectroscopic, chemical, and computational investigations for mechanistic insights.

Main Results:

• Generation of a photoexcited dianionic super-reductant exceeding the potency of lithium metal.
• Successful cleavage of strong carbon-fluorine bonds and reduction of other halides.
• Demonstration of radical quenching and C-C, C-P bond formations, as well as Birch-type reductions.

Conclusions:

• Multi-PET catalysis offers a powerful new strategy for organic synthesis.
• The generated super-reductant enables previously difficult chemical transformations.
• Mechanistic understanding was gained through comprehensive investigations.