The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

K. Yuan; R. J. Kahan; C. Si; A. Williams; S. Kirschner; M. Uzelac; E. Zysman-Colman; M. J. Ingleson

doi:10.1039/c9sc05404a

The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

K. Yuan, R. J. Kahan, C. Si, A. Williams, S. Kirschner, M. Uzelac, E. Zysman-Colman, M. J. Ingleson

Department of Chemistry

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Abstract

The synthesis of a range of brominated-B_n-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr₃ with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-B_n-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B₂-doped PAHs (with one example having a reduction potential of E_1/2 = -0.96 V versus Fc⁺/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the B_n-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B₂-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

Original language	English
Pages (from-to)	3258-3267
Number of pages	10
Journal	Chemical Science
Volume	11
Issue number	12
DOIs	https://doi.org/10.1039/c9sc05404a
Publication status	Published - 28 Mar 2020

ASJC Scopus subject areas

Chemistry(all)

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@article{9f24ca46e90149279d8196e769bcbaac,

title = "The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies",

abstract = "The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.",

author = "K. Yuan and Kahan, {R. J.} and C. Si and A. Williams and S. Kirschner and M. Uzelac and E. Zysman-Colman and Ingleson, {M. J.}",

note = "Funding Information: The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/ 1). C. Si thanks the China Scholarship Council (201806890001). Dr G. Nichol is thanked for the collection of X-ray diffraction data, Dr G. Whitehead for the structure of 2a and Dr A. Woodward for collecting photophysical data on compound 2c (see ESI‡). Publisher Copyright: This journal is {\textcopyright} The Royal Society of Chemistry.",

year = "2020",

month = mar,

day = "28",

doi = "10.1039/c9sc05404a",

language = "English",

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journal = "Chemical Science",

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TY - JOUR

T1 - The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration

T2 - Mechanistic and functionalisation studies

AU - Yuan, K.

AU - Kahan, R. J.

AU - Si, C.

AU - Williams, A.

AU - Kirschner, S.

AU - Uzelac, M.

AU - Zysman-Colman, E.

AU - Ingleson, M. J.

N1 - Funding Information: The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/ 1). C. Si thanks the China Scholarship Council (201806890001). Dr G. Nichol is thanked for the collection of X-ray diffraction data, Dr G. Whitehead for the structure of 2a and Dr A. Woodward for collecting photophysical data on compound 2c (see ESI‡). Publisher Copyright: This journal is © The Royal Society of Chemistry.

PY - 2020/3/28

Y1 - 2020/3/28

N2 - The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

AB - The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

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U2 - 10.1039/c9sc05404a

DO - 10.1039/c9sc05404a

M3 - Article

AN - SCOPUS:85082669570

SN - 2041-6520

VL - 11

SP - 3258

EP - 3267

JO - Chemical Science

JF - Chemical Science

IS - 12

ER -

The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: Mechanistic and functionalisation studies

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