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Abstract Covalent organic frameworks linked by carbon‐carbon double bonds (C=C COFs) are an emerging class of crystalline, porous, and conjugated polymeric materials with potential applications in organic electronics, photocatalysis, and energy storage. Despite the rapidly growing interest in sp2carbon‐conjugated COFs, only a small number of closely related condensation reactions have been successfully employed for their synthesis to date. Herein, we report the first example of a C=C COF, CORN‐COF‐1 (CORN=Cornell University), prepared byN‐heterocyclic carbene (NHC) dimerization. In‐depth characterization reveals that CORN‐COF‐1 possesses a two‐dimensional layered structure and hexagonal guest‐accessible pores decorated with a high density of strongly reducing tetraazafulvalene linkages. Exposure of CORN‐COF‐1 to tetracyanoethylene (TCNE,E1/2=0.13 V and −0.87 V vs. SCE) oxidizes the COF and encapsulates the radical anion TCNE⋅−and the dianion TCNE2−as guest molecules, as confirmed by spectroscopic and magnetic analysis. Notably, the reactive TCNE⋅−radical anion, which generally dimerizes in the solid state, is uniquely stabilized within the pores of CORN‐COF‐1. Overall, our findings broaden the toolbox of reactions available for the synthesis of redox‐active C=C COFs, paving the way for the design of novel materials.
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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 sp2carbon‐conjugation was synthesized and used to coordinate NiIIcenters 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.
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- Award ID(s):
- 2102554
- PAR ID:
- 10399424
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 11
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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