Triplet state stabilization and synergistic energy transfer in BOPHY-functionalized NU-1000 for enhanced photocatalytic aerobic oxidation

Abstract

Herein, we report the post-synthetic incorporation of an iodinated boron-difluoroboron hydrazone photosensitizer (I-BOPHYPhCOOH) into a zirconium-based metal–organic framework (NU-1000) via solvent-assisted ligand incorporation (SALI). In methanol, the spatial confinement within the hierarchical pores of NU-1000 significantly prolongs the triplet state lifetime of the anchored I-BOPHY to 3.81 microseconds, effectively reducing solvent-induced non-radiative decay pathways observed in protic bulk solution. This stabilization of long-lived triplet states, combined with efficient resonance energy transfer from the excited pyrene linkers, maximizes the light-harvesting and oxygen-activation efficiency of the system. Consequently, I-BOPHY@NU-1000 exhibits exceptional photocatalytic activity and high selectivity for the oxidation of sulfides to sulfoxides under mild aerobic conditions. This work demonstrates how the synergistic interplay between framework-induced triplet stabilization and intrinsic chromophore energy transfer can be exploited to construct superior MOF-based photocatalysts.