Modulator-Induced Secondary Building Unit Control in Lanthanide–Porphyrin Metal–Organic Frameworks for Enhanced Photooxidation

Controlling secondary building units (SBUs) in metal-organic frameworks (MOFs) provides a powerful strategy for tuning their photophysical properties and enhancing photocatalytic performances, particularly in singlet oxygen-mediated reactions. Herein, we report the synthesis of a series of lanthanide-porphyrin frameworks (QPF-3, QPF-4, and QPF-5) via a modulator-induced approach, yielding diverse SBUs that range from dinuclear cluster to a one-dimensional rod SBU. Among these, QPF-5(Yb) with rod SBU exhibits the highest ¹O₂ generation efficiency and remarkably improved photocatalytic activity in oxidizing 1,5-dihydroxynaphthalene to juglone, achieving up to a 6.1-fold increase compared with QPF-4(Yb). Spectroscopic and electrochemical analyses reveal that this superior performance arises from synergistic effects between the Ln-SBUs and porphyrin ligands, which collectively facilitate improved visible-light conversion efficiency and enhanced ¹O₂ generation efficiency. This work underscores the significance of modulator selection in achieving specific structural features and optimizing photocatalytic performance in Ln-porphyrin MOFs. The insights gained here contribute to the broader design principles for creating advanced photocatalytic systems capable of efficient reactive oxygen species production and selective oxidative transformations.