Extended Single-Electron Transfer Model and Dynamically Associated Energy Transfer Event in a Dual-Functional...

Area of Science:

• Organic Chemistry
• Photocatalysis
• Reaction Mechanisms

Background:

• Organic photocatalysis commonly employs energy transfer (EnT) or electron transfer (ET) for synthetic transformations.
• Integrating both EnT and ET in a single system with mechanistic understanding is underdeveloped.

Purpose of the Study:

• To illustrate the mechanism and kinetics of dynamically coupled EnT and ET pathways.
• To investigate C-H functionalization via a cascade photochemical reaction involving isomerization and cyclization.
• To utilize riboflavin as a dual-functional organic photocatalyst.

Main Methods:

• Computational modeling using an extended single-electron transfer model for proton transfer-coupled cyclization.
• Kinetic evaluation of EnT-driven E → Z photoisomerization using Fermi's golden rule and the Dexter model.

Main Results:

• The study provides the first mechanistic illustration and kinetic assessment of combined EnT and ET processes in photocatalysis.
• A cascade photochemical transformation involving isomerization and cyclization was achieved.
• Computational analysis elucidated dynamic behaviors in proton transfer-coupled cyclization and its correlation with photoisomerization.

Conclusions:

• This work establishes a fundamental basis for understanding photocatalytic mechanisms involving combined EnT and ET strategies.
• The findings guide the design of single photosensitizers capable of multiple activation modes.
• It opens new avenues for developing advanced organic photocatalytic systems.