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.