Boosting Hot Electron Generation in Energy Center Embedded Metal-Organic Frameworks for Photocatalysis

The ligands in metal-organic framework (MOF) play as light absorption center and transfer photogenerated electrons to metal node through ligand-to-metal charge transfer (LMCT) during photocatalysis, and energy utilization efficiency is strongly restricted by the light inertness of ligands. Herein, a ligand updating strategy is proposed by inserting energy centers to MOFs to activate the inherent ligands, realizing boosting hot electron generation and photocatalytic activities via the cascaded proceeding of energy transfer and charge transfer. By taking PCN-777 (a zeotype mesoporous Zr-containing MOF) as an example, this study shows that the embedded energy center of 1-pyrenecarboxylic acid (PCA) can activate the inherent ligand of PCN-777 through triplet-triplet energy transfer, where triplet excitons would dissociate into photocarriers migrating to the Zr metal cluster via LMCT process. As expected, PCN-777-PCA exhibits promising activity in metallaphotocatalytic C─N cross-coupling reactions by offering abundant hot electrons for the involved dual photoredox cycles. This work provides a practical method for improving the photocatalytic application of MOFs by ligand updating.