TY  - JOUR
A1  - Mützel, Carina
A1  - Farrell, Jeffrey M.
A1  - Shoyama, Kazutaka
A1  - Würthner, Frank
T1  - 12b,24b-Diborahexabenzo[a,c,fg,l,n,qr]pentacene: A Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbon
JF  - Angewandte Chemie International Edition
N2  - Herein we devise and execute a new synthesis of a pristine boron-doped nanographene. Our target boron-doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B-doping arrangement. Our synthesis of this target, a doubly B-doped hexabenzopentacene (B\(_{2}\)-HBP), employs six net C−H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr\(_{3}\)/AlCl\(_{3}\)/2,6-dichloropyridine-mediated C−H borylation steps. As predicted by our calculations, B\(_{2}\)-HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o-dichlorobenzene solutions. Furthermore, B\(_{2}\)-HBP possesses a very low LUMO level, showing two reversible reductions at −1.00 V and −1.17 V vs. Fc\(^{+}\)/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B-doped polycyclic aromatic hydrocarbons.
KW  - aromaticity
KW  - polycycles
KW  - pentacene
KW  - near infrared emitter
KW  - boron
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318808
VL  - 61
IS  - 8
ER  - 
TY  - JOUR
A1  - Schnitzlein, Matthias
A1  - Mützel, Carina
A1  - Shoyama, Kazutaka
A1  - Farrell, Jeffrey M.
A1  - Würthner, Frank
T1  - PAHs Containing both Heptagon and Pentagon: Corannulene Extension by [5+2] Annulation
JF  - European Journal of Organic Chemistry
N2  - Utilizing Pd‐catalyzed [5+2] annulation a series of heptagon‐extended corannulenes could be synthesized from a borinic acid precursor furnished by C−H borylation strategy. Single‐crystal X‐ray analysis revealed the presence of two conformational enantiomers crystallizing in a racemic mixture. Through their embedded five‐ and seven‐membered rings these polycyclic aromatic hydrocarbons (PAHs) exhibit both negative and positive curvature and UV/Vis/NIR absorption spectroscopy as well as cyclic voltammetry experiments provided insights into the influence of larger flanking aromatic systems and electron‐donating substituents encompassing the heptagonal ring. Through [5+2] annulation of acenaphthylene an azulene‐containing PAH with intriguing optoelectronical properties including a very small bandgap and absorption over the whole visible spectrum could be obtained. Theoretical calculations were employed to elucidate the long‐wavelength absorption and aromaticity.
KW  - annulation
KW  - aromaticity
KW  - azulene
KW  - Corannulene
KW  - polycyclic aromatic hydrocarbons
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-262627
VL  - 2022
IS  - 5
ER  -