Donor-Acceptor-Donor Type Diimidazole-Based Metal-Organic Framework for Photocatalytic C-O and C-C Bond Formation

The development of robust, efficient, and recyclable heterogeneous photocatalysts for solar-driven organic synthesis remains a significant challenge. Herein, we report the synthesis of a robust hafnium-based metal-organic framework, JNU-228, by using a donor-acceptor-donor (D-A-D) ligand, 4,4',4″,4‴-(1,4-phenylenebis(1H-imidazole-2,4,5-triyl))tetrabenzoate (PBIT). The integration of photoactive triphenylimidazole units with Hf₆-oxo clusters endows JNU-228 with enhanced visible-light absorption and a suitable band gap. Under visible-light irradiation, JNU-228 efficiently catalyzes the hydroxylation of arylboronic acids and the trifluoromethylation of coumarins and indoles. Moreover, JNU-228 maintains its structural integrity and catalytic activity over multiple cycles. This work demonstrates that incorporating molecular D-A-D photosensitizers into stable MOF matrices is a powerful strategy for developing superior heterogeneous photocatalysts for sustainable organic transformations.