Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants

Marco S. Messina; Jonathan C. Axtell; Yiqun Wang; Paul Chong; Alex I. Wixtrom; Kent O. Kirlikovali; Brianna M. Upton; Bryan M. Hunter; Oliver S. Shafaat; Saeed I. Khan; Jay R. Winkler; Harry B. Gray; Anastassia N. Alexandrova; Heather D. Maynard; Alexander M. Spokoyny

doi:10.1021/jacs.6b03568

Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants

Marco S. Messina, Jonathan C. Axtell, Yiqun Wang, Paul Chong, Alex I. Wixtrom, Kent O. Kirlikovali, Brianna M. Upton, Bryan M. Hunter, Oliver S. Shafaat, Saeed I. Khan, Jay R. Winkler, Harry B. Gray, Anastassia N. Alexandrova, Heather D. Maynard, Alexander M. Spokoyny^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

81 Scopus citations

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 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 B₁₂(OCH₂C₆F₅)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.

Original language	English (US)
Pages (from-to)	6952-6955
Number of pages	4
Journal	Journal of the American Chemical Society
Volume	138
Issue number	22
DOIs	https://doi.org/10.1021/jacs.6b03568
State	Published - Jun 8 2016

ASJC Scopus subject areas

Chemistry(all)
Biochemistry
Catalysis
Colloid and Surface Chemistry

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Messina, M. S., Axtell, J. C., Wang, Y., Chong, P., Wixtrom, A. I., Kirlikovali, K. O., Upton, B. M., Hunter, B. M., Shafaat, O. S., Khan, S. I., Winkler, J. R., Gray, H. B., Alexandrova, A. N., Maynard, H. D., & Spokoyny, A. M. (2016). Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants. Journal of the American Chemical Society, 138(22), 6952-6955. https://doi.org/10.1021/jacs.6b03568

@article{8f046d534dcf4631895485d643f98b49,

title = "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 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 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 B12(OCH2C6F5)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.",

author = "Messina, {Marco S.} and Axtell, {Jonathan C.} and Yiqun Wang and Paul Chong and Wixtrom, {Alex I.} and Kirlikovali, {Kent O.} and Upton, {Brianna M.} and Hunter, {Bryan M.} and Shafaat, {Oliver S.} and Khan, {Saeed I.} and Winkler, {Jay R.} and Gray, {Harry B.} and Alexandrova, {Anastassia N.} and Maynard, {Heather D.} and Spokoyny, {Alexander M.}",

note = "Funding Information: 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. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

month = jun,

day = "8",

doi = "10.1021/jacs.6b03568",

language = "English (US)",

volume = "138",

pages = "6952--6955",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "American Chemical Society",

number = "22",

}

Messina, MS, Axtell, JC, Wang, Y, Chong, P, Wixtrom, AI, Kirlikovali, KO, Upton, BM, Hunter, BM, Shafaat, OS, Khan, SI, Winkler, JR, Gray, HB, Alexandrova, AN, Maynard, HD & Spokoyny, AM 2016, 'Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants', Journal of the American Chemical Society, vol. 138, no. 22, pp. 6952-6955. https://doi.org/10.1021/jacs.6b03568

TY - JOUR

T1 - Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants

AU - Messina, Marco S.

AU - Axtell, Jonathan C.

AU - Wang, Yiqun

AU - Chong, Paul

AU - Wixtrom, Alex I.

AU - Kirlikovali, Kent O.

AU - Upton, Brianna M.

AU - Hunter, Bryan M.

AU - Shafaat, Oliver S.

AU - Khan, Saeed I.

AU - Winkler, Jay R.

AU - Gray, Harry B.

AU - Alexandrova, Anastassia N.

AU - Maynard, Heather D.

AU - Spokoyny, Alexander M.

N1 - Funding Information: 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. Publisher Copyright: © 2016 American Chemical Society.

PY - 2016/6/8

Y1 - 2016/6/8

N2 - 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 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 B12(OCH2C6F5)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.

AB - 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 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 B12(OCH2C6F5)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.

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U2 - 10.1021/jacs.6b03568

DO - 10.1021/jacs.6b03568

M3 - Article

C2 - 27186856

AN - SCOPUS:84974814506

SN - 0002-7863

VL - 138

SP - 6952

EP - 6955

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 22

ER -

Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants

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