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  - Bachmann, Jonas
A1  - Helbig, Andreas
A1  - Crumbach, Merian
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Helten, Holger
T1  - Fusion of Aza‐ and Oxadiborepins with Furans in a Reversible Ring‐Opening Process Furnishes Versatile Building Blocks for Extended π‐Conjugated Materials
JF  - Chemistry – A European Journal
N2  - A modular synthesis of both difurooxa‐ and difuroazadiborepins from a common precursor is demonstrated. Starting from 2,2′‐bifuran, after protection of the positions 5 and 5’ with bulky silyl groups, formation of the novel polycycles proceeds through opening of the furan rings to a dialkyne and subsequent re‐cyclization in the borylation step. The resulting bifuran‐fused diborepins show pronounced stability, highly planar tricyclic structures, and intense blue light emission. Deprotection and transformation into dibrominated building blocks that can be incorporated into π‐extended materials can be performed in one step. Detailed DFT calculations provide information about the aromaticity of the constituent rings of this polycycle.
KW  - aromaticity
KW  - boron
KW  - BN compounds
KW  - furan
KW  - polycycles
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-293926
VL  - 28
IS  - 63
ER  - 
TY  - JOUR
A1  - Crumbach, Merian
A1  - Bachmann, Jonas
A1  - Fritze, Lars
A1  - Helbig, Andreas
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Helten, Holger
T1  - Dithiophene‐Fused Oxadiborepins and Azadiborepins: A New Class of Highly Fluorescent Heteroaromatics
JF  - Angewandte Chemie International Edition
N2  - Access to dithiophene‐fused oxadiborepins and the first azadiborepins attained via a modular synthesis route are presented. The new compounds emit intense blue light, some of which demonstrate fluorescence quantum yields close to unity. Cyclic voltammetry (CV) revealed electrochemically reversible one‐electron reduction processes. The weak aromatic character of the novel 1,2,7‐azadiborepin ring is demonstrated with in‐depth theoretical investigations using nucleus‐independent chemical shift (NICS) scans and anisotropy of the induced current density (ACID) calculations.
KW  - aromaticity
KW  - BN compounds
KW  - boron
KW  - isoelectronic analogues
KW  - polycycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-238996
VL  - 60
IS  - 17
SP  - 9290
EP  - 9295
ER  -