Pyrene-based porous organic materials for visible light photocatalysis

Solar -driven redox chemical processes necessitate the discovery of new photocatalytic materials. As such, pyrenebased porous organic materials have recently been constructed based on resilient and photoactive pyrenes. With a planar pi-conjugation, pyrene can be extended toward the foundational building blocks. In principle, pyrenebased porous organic materials can be designed and constructed as potent photocatalysts. Generally, there are two types of covalent bonds, irreversible and reversible, that knit pyrene molecular building blocks for the construction of porous organic materials. Conjugated microporous polymers (CMPs) are generated with irreversible covalent bonds, whereas covalent organic frameworks (COFs) are afforded with reversible ones. Pyrenebased CMPs and COFs can drive various significant photocatalytic reactions, such as selective reduction of protons, carbon dioxide, toxic metals, and oxygen, and selective oxidation of organic molecules. Compared to amorphous CMPs, crystallinity defines COFs. The structure-activity relationships of pyrene-based CMPs and COFs are thoroughly summarized, discussed, and compared in this Review. Note that a reduction event is always associated with an oxidation event and vice versa. Moreover, an electron transfer is typically accompanied by a proton transfer for a complete photocatalytic reaction. Notably, the reaction mechanisms of visible light photocatalysis over pyrene-based CMPs and COFs are also discussed meticulously. This Review can provide a blueprint for developing state-of-the-art porous organic materials for solar photocatalysis.