Donor-acceptor mixed-ligand MOF with energy transfer-mediated high-efficiency singlet oxygen generation for boosted...

Integrating energy donor and acceptor chromophores as ligands within one MOF for advanced artificial photosynthesis is of great interest but appears to be a major challenge. Herein, via a simple one-pot synthetic strategy, an energy acceptor porphyrin ligand 5,15-di(p-benzoato)porphyrin (H₂DPBP) was successfully integrated into an energy donor 1,4-naphthalenedicarboxylic acid (H₂NDC)-based MOF (UiO-66-NDC) to construct a mixed-ligand MOF, donated as UiO-66-NDC-H₂DPBP. Benefiting from the ample overlap between the emission spectrum of H₂NDC and the absorption spectrum of H₂DPBP, an efficient energy transfer (EnT) process from the donor H₂NDC to the acceptor H₂DPBP within UiO-66-NDC-H₂DPBP can occur and be captured by time-resolved spectroscopy. Furthermore, the singlet oxygen (¹O₂) generation efficiency of UiO-66-NDC-H₂DPBP mediated by this EnT process as well as the EnT process from the triplet state (T₁) of the photosensitizer H₂DPBP ligand to the ground state of molecular oxygen (³O₂) upon light irradiation can be maximized via simply regulating the loading amount of H₂DPBP, leading to boosted photocatalytic activities toward important aerobic oxidation reactions of amines and sulfides, even under sunlight and ambient air. This work explores an avenue to construct high-efficiency energy donor and acceptor-based light-harvesting systems by utilizing mixed-ligand MOFs as platforms to advanced artificial photosynthesis.