Heavy-atom node engineering in perylene diimide-based MOFs for efficient singlet-oxygen-mediated aerobic oxidation

Isostructural Hf- and Zr-based PDI-MOFs reveal metal-node effects. • Hf nodes enhance spin-orbit coupling and intersystem crossing. • Hf nodes promote triplet excitons and singlet oxygen generation. • PDI-MOF(Hf) enables rapid and selective sulfide oxidation. Efficient singlet oxygen ( 1 O 2 )-mediated selective oxidation requires photocatalysts capable of promoting intersystem crossing and enriching triplet states. Metal-organic frameworks (MOFs) provide a multifunctional platform for photocatalytic detoxification, yet how metal nodes regulate excited-state dynamics and triplet exciton formation remains insufficiently understood. Herein, we construct two isostructural perylene diimide (PDI)-based MOFs to systematically elucidate node-dependent spin-orbit coupling effects. The Hf nodes promote spin-related excited-state evolution through a heavy-atom effect, favoring triplet-state formation and 1 O 2 generation. As a result, the Hf-based MOF PDI-MOF(Hf) exhibits outstanding performance in mustard gas simulant detoxification, achieving a half-life of ≈ 4 min while maintaining high selectivity, and exhibits wide-ranging applications in the selective oxidation of aromatic sulfides into sulfoxides. Phosphorescence and in-situ electron paramagnetic resonance spectroscopy measurements corroborate the enhanced triplet-state processes and dominant 1 O 2 -mediated pathway. This work establishes a clear correlation between heavy-atom node engineering and spin-dependent photophysics, providing a general strategy to overcome intersystem crossing limitations in organic chromophores and advancing the rational design of MOF photocatalysts for detoxification and selective oxidation. Download: Download high-res image (190KB) Download: Download full-size image