Cobalt Porphyrin-Based Polyimide Covalent Organic Framework for Efficient Photocatalytic Oxidation of Styrene and Phenylboronic Acid

Conventional synthesis of organic substances predominantly relies on thermal energy, often leading to substantial energy consumption and environmental concerns. Harnessing inexhaustible solar energy enables sustainable catalytic pathways for organic synthesis. Consequently, the development of efficient photocatalysts is of paramount importance. Herein, two porphyrin-based polyimide covalent organic frameworks (PI-COFs), PI-TPP and PI-CTP, were constructed using tetra(4-aminophenyl)porphyrin (TAPP) and its cobalt-metalized analogue (Co-TAPP), respectively. Combined experimental and theoretical calculations confirmed that the introduction of cobalt sites broadens the light absorption range, narrows the band gap, and promotes carrier separation and migration, collectively leading to a remarkable enhancement in the photocatalytic oxidation performance. Remarkably, in the photocatalytic oxidation of styrene, PI-CTP achieved nearly 100% conversion within 4 h, far surpassing the 49% conversion attained by PI-TPP. Similarly, for the photocatalytic oxidation of phenylboronic acid, PI-CTP provided phenol in nearly 100% yield after 8 h, in sharp contrast to the 56% yield obtained with PI-TPP. This work establishes porphyrin-based PI-COFs as promising photocatalysts for efficient photocatalytic oxidation while demonstrating that the introduction of cobalt sites enhances photoelectric properties and significantly boosts photocatalytic efficiency.