Programmable Photocatalytic Activity of Multicomponent Covalent Organic Frameworks Used as Metallaphotocatalysts

The multicomponent approach allows to incorporate several functionalities into a single covalent organic framework (COF) and consequently allows the construction of bifunctional materials for cooperative catalysis. The well-defined structure of such multicomponent COFs is furthermore ideally suited for structure-activity relationship studies. We report a series of multicomponent COFs that contain acridine- and 2,2'-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives. The acridine motif is responsible for broad light absorption, while the bipyridine unit enables complexation of nickel catalysts. These features enable the usage of the framework materials as catalysts for light-mediated carbon-heteroatom cross-couplings. Variation of the node units shows that the catalytic activity correlates to the keto-enamine tautomer isomerism. This allows switching between high charge-carrier mobility and persistent, localized charge-separated species depending on the nodes, a tool to tailor the materials for specific reactions. Moreover, nickel-loaded COFs are recyclable and catalyze cross-couplings even using red light irradiation.

Automated summary

The multicomponent approach is used to create bifunctional materials for cooperative catalysis by incorporating multiple functionalities into a single covalent organic framework (COF). These COFs have a well-defined structure for structure-activity relationship studies. Nickel-loaded COFs containing acridine and 2,2'-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives are reported. The acridine motif enables broad light absorption, while the bipyridine unit allows complexation of nickel catalysts, making the framework materials suitable for light-mediated carbon-heteroatom cross-couplings. Switching between high charge-carrier mobility and charge-separated species can be achieved by varying the node units, tailoring the materials for specific reactions. Nickel-loaded COFs are recyclable and can catalyze cross-couplings using red light irradiation.