Porosity-Controlled Photoinduced Electron Transfer Pathways in Radical Anionic MOFs

Owing to well-defined topologies and structural orderings, metal-organic frameworks (MOFs) can serve as a prototype platform for designing new energy materials with predesigned structures for efficient energy and electron transfer. This study explores the photoinduced electron transfer dynamics of monoanionic radicals within two different UiO-type MOFs, distinguished by their degree of interpenetration. In 0-MOF, which has relatively large pores (18.6 Å), electron transfer is primarily facilitated by solvent-assisted electron hopping, with dimethylformamide (DMF) molecules serving as bridges between naphthalenediimide (NDI)-based ligands. In contrast, the smaller pores (12.1 Å) of 100-MOF admit only one or two DMFs, favoring direct through-space electron transfer between neighboring NDI units. This comparative study highlights the role of pore size and intermolecular interactions in governing the electron transfer mechanisms within MOFs. These findings contribute to a better understanding of the photophysical properties of MOFs and open new avenues for their potential use in future energy applications.