Paddle-Wheel BODIPY-Hexaoxatriphenylene Conjugates: Participation of Redox-Active Hexaoxatriphenylene in Excited-State Charge Separation to Yield High-Energy Charge-Separated States.

Hexaoxatriphenylene, a scaffold linker often utilized in building covalent organic frameworks, is shown to be electroactive and a useful entity to build light energy-harvesting donor-acceptor systems. To demonstrate this, new donor-acceptor conjugates have been synthesized by employing BODIPY as a sensitizer. Excited-state electron transfer leading to high-energy charge-separated states, useful to drive energy-demanding photocatalytic reactions, from the electron-rich hexaoxatriphenylene to 1 BODIPY*, in the synthesized tri-BODIPY-hexaoxatriphenylene "paddle-wheel" conjugates, has been successfully demonstrated using femtosecond transient absorption spectroscopy. The measured rate of charge separation was in the range of ∼3-10 × 1011 s-1 , revealing ultrafast charge separation.