Polyoxometalate-Scaffolded Perylene Diimide Dimers: Preorganization and Dynamic Charge Regulation for Enhanced and Durable Photosensitization.

Precise control over both chromophore geometry and photoinduced charge dynamics is essential for engineering excited-state processes, yet achieving both simultaneously remains a major challenge. Here, we report a polyoxometalate (POM)-scaffolded strategy that integrates structural preorganization with dynamic charge regulation in perylene diimide (PDI) dimers. Rigid, redox-active lacunary POM clusters preorganize two PDIs into a tightly stacked, parallel-displaced, rotationally aligned arrangement favorable for excimer formation. This preorganization enables ultrafast excimer formation, prolongs excited-state lifetimes, and promotes efficient singlet oxygen generation. Beyond structural preorganization, the POM scaffolds actively regulate excited-state charge dynamics by acting as intramolecular charge buffers, suppressing radical-induced photodegradation under aerobic conditions. The combination of geometric control and dynamic charge regulation affords durable photosensitization, establishing inorganic molecular clusters as multifunctional scaffolds for excited-state engineering.