Enhancing Triplet‐Triplet Annihilation Upconversion of Pyrene Derivatives for Photoredox Catalysis via Molecular Engineering

Abstract

AbstractTriplet‐triplet annihilation upconversion (TTA‐UC) has the potential to enhance photoredox catalysis yield. It includes a sensitizer and an annihilator. Efficient and stable annihilators are essential for photoredox catalysis, yet only a few examples are reported. Herein, we designed four novel pyrene annihilators (1, 2, 3 and 4) via introducing aryl‐alkynyl groups onto pyrene to systematically modulate their singlet and triplet energies. Coupled with platinum octaethylporphyrin (PtOEP), the TTA‐UC efficiency is enhanced gradually as the number of aryl‐alkynyl group increases. When combining 4 with palladium tetraphenyl‐tetrabenzoporphyrin (PdTPTBP), we achieved the highest red‐to‐green upconversion efficiency (22.4±0.3 %) (out of a 50 % maximum) so far. Then, this pair was used to activate photooxidation of aryl boronic acid under red light (630 nm), which achieved a great improved reaction yield compared to that activated by green light directly. The results not only provide a design strategy for efficient annihilators, but also show the advantage of applying TTA‐UC into improving the photoredox catalysis yield.