Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants
- 26 May 2016
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 138 (22), 6952-6955
- https://doi.org/10.1021/jacs.6b03568
Abstract
We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a bench-top blue LED source, can exhibit excited-state reduction potentials as high as 3 Volts and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is ob-served in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.05 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the pres-ence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable metal-free photoredox reagents capable of mediating chemical transformations.Keywords
Funding Information
- Division of Chemistry (CHE-1351968, CHE-1507735)
- National Institute of Diabetes and Digestive and Kidney Diseases (DK019037)
- Arnold and Mabel Beckman Foundation
- National Science Foundation
- Department of Chemistry and Biochemistry, University of California, Los Angeles
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