Red-Light-Based Effective Photocatalysis of a Photosensitive Covalent Organic Framework Triggered Singlet Oxygen

The direct application of low-energy red light for photochemical transformations is synthetically appealing but practically challenging. Covalent organic frameworks (COFs) exhibit significant potential within this domain, owing to their broad spectrum of absorption and their prevalence in photochemical reactions, despite the fact that these photocatalysts are now mainly focused on using ultraviolet (UV) and blue light. In this study, an imidazole-linked porphyrin-based COF, PyPor-COF, which exhibits a wide absorption band ranging from 200 to 700 nm, especially strong red light absorption from 630 to 700 nm, is expected to be applied in red light photocatalytic reactions. PyPor-COF possesses the capacity to selectively generate singlet oxygen (O-1(2)) with a high efficiency, which renders it an efficient photosensitizer for photocatalytic reactions of olefin cleavages and thioanisole photooxidation under red light. The present study demonstrates the intriguing prospect of photoactive COFs with red light absorption as a type II photosensitizer with high potential for utilization in red light photocatalyses.