Enhanced Energy Transfer in A π‐Conjugated Covalent Organic Framework Facilitates Excited‐State Nickel Catalysis

Abstract

Covalent organic frameworks (COFs) have received broad interest owing to their permanent porosity, high stability, and tunable functionalities. COFs with long-range π-conjugation and photosensitizing building blocks have been explored for sustainable photocatalysis. Herein, we report the first example of COF-based energy transfer Ni catalysis. A pyrene-based COF with sp 2 carbon-conjugation was synthesized and used to coordinate Ni II centers through bipyridine moieties. Under light irradiation, enhanced energy transfer in the COF facilitated the excitation of Ni centers to catalyze borylation and trifluoromethylation reactions of aryl halides. The COF showed two orders of magnitude higher efficiency in these reactions than its homogeneous control and could be recovered and reused without significant loss of catalytic activity.

Covalent organic frameworks in heterogeneous catalysis: recent advances and future perspective

“…104 Since then, considerable progress has been made in the design of COF photoredox catalysts through the backbone, linkage, and heterostructure engineering (Table 2 and Scheme 4). 105–107…”

“…104 Since then, considerable progress has been made in the design of COF photoredox catalysts through the backbone, linkage, and heterostructure engineering (Table 2 and Scheme 4). [105][106][107] Backbone engineering. To promote photocatalytic efficiency, the COF structure can be tailored by subtle modulations in the backbone to maximize light harvesting and charge separation.…”

Bis-ferrocenyl-hydrazide metal complexes: studying electronic functional groups as newly potent homogeneous photocatalysts for C(sp3)–H and C(sp2)–H bond oxidation utilizing visible light condition

“…16,24,25 New designs of nickel complexes in covalent organic framework (COF) scaffolds and organic semiconductors such as graphitic carbon nitride (g-C 3 N 4 ) for photocatalytic applications have also been introduced. 26,27 One of the most common ligands used by organometallic chemists to design efficient optical complexes is Schiff bases. Schiff bases have been studied as a ligand for the synthesis of transition metal complexes in coordination chemistry from the past to the present, and have many applications as catalysts and drug molecules.…”

“…16,24,25 New designs of nickel complexes in covalent organic framework (COF) scaffolds and organic semiconductors such as graphitic carbon nitride (g-C 3 N 4 ) for photocatalytic applications have also been introduced. 26,27…”