Abstract
2,2’-Bis(4-dimethylaminophenyl)- and 2,2'-dicyclohexyl-1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazole ((N-DMBI)2 and (Cyc-DMBI)2) are quite strong reductants with effective potentials of ca. −2 V vs ferrocenium/ferrocene, yet are relatively stable to air due to the coupling of redox and bond-breaking processes. Here, we examine their use in accomplishing electron transfer-induced bond-cleavage reactions, specifically dehalogenations. The dimers reduce halides that have reduction potentials less cathodic than ca. −2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The potentials of the halides that can be reduced in this way, quantum-chemical calculations, and steady-state and transient absorption spectroscopy suggest that UV irradiation accelerates the reactions via cleavage of the dimers to the corresponding radical monomers.
Document Type
Article
Publication Date
12-2023
Digital Object Identifier (DOI)
https://doi.org/10.3762/bjoc.19.142
Funding Information
This work was authored in part by the National Renewable Energy Laboratory (NREL), operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. This work was primarily supported by the Laboratory Directed Research and Development (LDRD) Program at NREL. The DFT and TD-DFT calculations, performed at the University of Kentucky, were supported by the Center for Soft PhotoElectroChemical Systems (SPECS), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award No. DE-SC0023411. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.
Repository Citation
Tang, Kan; Brown, Megan R.; Risko, Chad; Gish, Melissa K.; Rumbles, Garry; Pham, Phuc H.; Luca, Oana R.; Barlow, Stephen; and Marder, Seth R., "Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides" (2023). UK CARES Faculty Publications. 73.
https://uknowledge.uky.edu/ukcares_facpub/73
Notes/Citation Information
© 2023 Tang et al.; licensee Beilstein-Institut.