Red light-driven electron sacrificial agents-free photoreduction of inert aryl halides via triplet-triplet annihilation
Zeng, Le ; Huang, Ling ; Lin, Wenhai ; Jiang, Lin-Han ; Han, Gang
Citations
Student Authors
Faculty Advisor
Academic Program
UMass Chan Affiliations
Document Type
Publication Date
Keywords
Subject Area
Files
Embargo Expiration Date
Link to Full Text
Abstract
Selective photoactivation of inert aryl halides is a fundamental challenge in organic synthesis. Specially, the long-wavelength red light is more desirable than the widely-applied blue light as the excitation source for photoredox catalysis, due to its superior penetration depth. However, the long-wavelength red light-driven photoactivation of inert aryl halides remains a challenge, mainly because of the low energy of the single long-wavelength red photon. Herein, we report the photoreduction of aryl bromides/chlorides with 656 nm LED via triplet-triplet annihilation (TTA) strategy. This method is based on our discovery that the commonly used chromophore of perylene can serve as an efficient and metal-free photocatalyst to enable the photoreduction of inert aryl halides without the conventional need for electronic sacrificial agents. By introducing a red light-absorbing photosensitizer to this perylene system, we accomplish the long-wavelength red light-driven photoreduction of aryl halides via sensitized TTA mechanism. Moreover, the performance of such a TTA-mediated photoreduction can be significantly enhanced when restricting the rotation freedom of phenyl moiety for perylene derivatives to suppress their triplet nonradiative transition, in both small and large-scale reaction settings.
Source
Zeng L, Huang L, Lin W, Jiang LH, Han G. Red light-driven electron sacrificial agents-free photoreduction of inert aryl halides via triplet-triplet annihilation. Nat Commun. 2023 Feb 27;14(1):1102. doi: 10.1038/s41467-023-36679-7. PMID: 36843133; PMCID: PMC9968713.