Highly Stable, Readily Reducible, Fluorescent, Trifluoromethylated 9‐Borafluorenes

Please always quote using this URN: urn:nbn:de:bvb:20-opus-218390
  • Three different perfluoroalkylated borafluorenes (\(^{F}\)Bf) were prepared and their electronic and photophysical properties were investigated. The systems have four trifluoromethyl moieties on the borafluorene moiety as well as two trifluoromethyl groups at the ortho positions of their exo‐aryl moieties. They differ with regard to the para substituents on their exo‐aryl moieties, being a proton \(^{F}\)Xyl\(^{F}\)Bf, \(^{F}\)Xyl: 2,6‐bis(trifluoromethyl)phenyl), a trifluoromethyl group (\(^{F}\)Mes\(^{F}\)Bf, \(^{F}\)Mes:Three different perfluoroalkylated borafluorenes (\(^{F}\)Bf) were prepared and their electronic and photophysical properties were investigated. The systems have four trifluoromethyl moieties on the borafluorene moiety as well as two trifluoromethyl groups at the ortho positions of their exo‐aryl moieties. They differ with regard to the para substituents on their exo‐aryl moieties, being a proton \(^{F}\)Xyl\(^{F}\)Bf, \(^{F}\)Xyl: 2,6‐bis(trifluoromethyl)phenyl), a trifluoromethyl group (\(^{F}\)Mes\(^{F}\)Bf, \(^{F}\)Mes: 2,4,6‐tris(trifluoromethyl)phenyl) or a dimethylamino group (p‐NMe\(_{2}\)‐\(^{F}\)Xyl\(^{F}\)Bf, p‐NMe\(_{2}\)‐\(^{F}\)Xyl: 4‐(dimethylamino)‐2,6‐bis(trifluoromethyl)phenyl), respectively. All derivatives exhibit extraordinarily low reduction potentials, comparable to those of perylenediimides. The most electron‐deficient derivative \(^{F}\)Mes\(^{F}\)Bf was also chemically reduced and its radical anion isolated and characterized. Furthermore, all compounds exhibit very long fluorescent lifetimes of about 250 ns up to 1.6 μs; however, the underlying mechanisms responsible for this differ. The donor‐substituted derivative p‐NMe\(_{2}\)‐\(^{F}\)Xyl\(^{F}\)Bf exhibits thermally activated delayed fluorescence (TADF) from a charge‐transfer (CT) state, whereas the \(^{F}\)Mes\(^{F}\)Bf and FXylFBf borafluorenes exhibit only weakly allowed locally excited (LE) transitions due to their symmetry and low transition‐dipole moments.show moreshow less

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Metadaten
Author: Florian Rauch, Sonja Fuchs, Alexandra Friedrich, Daniel Sieh, Ivo Krummenacher, Holger BraunschweigORCiD, Maik Finze, Todd B. Marder
URN:urn:nbn:de:bvb:20-opus-218390
Document Type:Journal article
Faculties:Fakultät für Chemie und Pharmazie / Institut für Anorganische Chemie
Language:English
Parent Title (English):Chemistry – A European Journal
Year of Completion:2020
Volume:26
Issue:56
First Page:12794
Last Page:12808
Source:Chemistry – A European Journal 2020, 26(56):12794–12808. DOI: 10.1002/chem.201905559
DOI:https://doi.org/10.1002/chem.201905559
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Tag:EPR spectroscopy; borafluorenes; boron; fluorescence; heterocycles
Release Date:2021/07/16
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International