Organized Aggregation Makes Insoluble Perylene Diimide Efficient for the Reduction of Aryl Halides via Consecutive Visible Light-Induced Electron-Transfer Processes

The consecutive photo-induced electron transfer (conPET) process found with perylene diimide (PDI) overcomes the limitation of visible-light photo catalysis and sheds light on effective solar energy conversion: By the incorporation of PDI into a metal organic polymer Zn-PDI, a heterogeneous approach was achieved to tackle the poor solubility and strong tendency to aggregate of PDIs that restricted the exploitation of this outstanding homogeneous process. The interplay between metal-PDI coordination and pi-pi stacking of the organized PDI arrays in Zn-PDI facilitates the conPET process for the visible light-driven reduction of aryl halides by stabilizing the radical-anion intermediate and catalyst substrate interacted moiety. These synergistic effects between the PDI arrays and Zn sites further render Zn-PDI photoactivity for fundamental oxidation of benzyl alcohols and amines. The tunable and modular nature of the two-dimensional metal-organic polymers makes the catalyst-embedding strategy promising for the development of ideal photocatalysts toward the better utilization of solar energy.