Cobalt-Metalated 1D Perylene Diimide Carbon-Organic Framework for Enhanced Photocatalytic α-C(sp3)─H Activation and CO2 Reduction

The photocatalytic activation of inert C(sp³)─H bonds in saturated aza-heterocycles provides a direct and efficient route to high-value α-amino amides but remains challenging due to intrinsically high bond dissociation energies. Herein, we report a cobalt-metalated, one-dimensional ABC-stacking covalent organic framework (PP-COF-Co), integrating perylene diimide (PDI) as a photosensitizer and 1,10-phenanthroline as a metal coordination site. Cobalt metalation significantly enhances photocatalytic efficiency, enabling the α-C(sp³)─H carbamoylation of saturated aza-heterocycles with yields of up to 91%, far surpassing its non-metalated counterpart (59%). This enhancement arises from the synergistic interplay between the PDI units and cobalt centers, which promote electron-hole pair separation and enhance singlet oxygen (¹O₂) generation. Moreover, PP-COF-Co exhibits a 57-fold increase in photocatalytic CO₂ reduction activity compared to its pristine analogue. This work highlights the critical role of metalation in modulating charge dynamics within COF-based photocatalysts and offers insights into the development of next-generation materials for sustainable catalysis.