Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants
Abstract
We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B_(12)(OCH_2Ar)_(12) (Ar = Ph or C_6F_5) 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 benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B_(12)(OCH_2C_6F_5)_(12) in the presence 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 photo-redox reagents capable of mediating chemical transformations.
Additional Information
© 2016 American Chemical Society. Received: April 6, 2016. Published: May 17, 2016. A.M.S. thanks the UCLA Department of Chemistry and Biochemistry for start-up funds and 3M for a Non-Tenured Faculty Award. M.S.M. thanks the NSF for the Bridge-to-Doctorate and the Predoctoral (GRFP) Fellowships. H.B.G. and O.S.S. acknowledge funding from the NIH (R01DK019038) and the Arnold and Mabel Beckman Foundation. A.N.A. thanks the NSF for CAREER Award CHE-1351968. Y.W. thanks the CSST Scholarship. H.D.M. thanks the NSF (CHE-1507735) for funding. B.M.U. thanks UCLA for a Dissertation Year Fellowship. The authors thank Mr. Daniel Hatfield (UCLA) for assistance with computational studies and Prof. Andrea Kasko (UCLA) for generously allowing access to her GPC instrument. Author Contributions: M.S.M. and J.C.A. contributed equally to the project. The authors declare no competing financial interest.Attached Files
Accepted Version - eScholarship_UC_item_7zz1g6fx.pdf
Supplemental Material - ja6b03568_si_001.pdf
Supplemental Material - ja6b03568_si_002.cif
Supplemental Material - ja6b03568_si_003.mov
Files
Additional details
- Eprint ID
- 67877
- DOI
- 10.1021/jacs.6b03568
- Resolver ID
- CaltechAUTHORS:20160613-124225978
- UCLA
- 3M
- NSF Predoctoral Fellowship
- R01DK019038
- NIH
- Arnold and Mabel Beckman Foundation
- CHE-1351968
- NSF
- CHE-1507735
- NSF
- Created
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2016-06-13Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field