Anthraquinone-Engineered Thiophene-Based Nanotube-Like Porous Aromatic Framework as a Robust and Efficient Bifunctional Photocatalyst for C─H Cyanation of Tertiary Amines and Hydrogen Peroxide Generation.

Abstract

The development of stable organic semiconductor photocatalysts-those capable of withstanding harsh conditions while maintaining high activity-remains a significant challenge. To this end, this study proposes an anthraquinone engineering strategy that aims to simultaneously enhance both structural stability and catalytic efficiency of organic semiconductors for photocatalysis. Specifically, 1,3,5-tri(thiophen-2-yl)benzene (TTB)-based porous aromatic frameworks (PAFs) (TTB-PAFs) are optimized by linking anthraquinone fragments via carbon-carbon bond formation. The unique electron distribution, abundant active sites, nanotube-like micromorphology, and robust carbon-carbon bonding character of the optimized TTB-PAF jointly facilitate the charge separation/transfer, mass transportation, and stability during photocatalysis. Remarkably, these result in the optimal C─H cyanation of tertiary amines over the PAF-396 photocatalyst, achieving excellent yields (up to 99%), good substrate adaptability (18 examples), and good recyclability (10 cycles), thereby surpassing the performance of reported porous organic semiconductor materials under similar conditions. Furthermore, PAF-396 also achieves efficient photosynthesis of hydrogen peroxide (H2O2) with a high synthesis rate of 5154 µmol g-1 h-1 from air and water without a sacrificial reagent under blue LED lamp irradiation.