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
photocatalysis 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 π···π 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.