Highly Stable, Readily Reducible, Fluorescent, Trifluoromethylated 9-Borafluorenes.
Chemistry
; 26(56): 12794-12808, 2020 Oct 06.
Article
en En
| MEDLINE
| ID: mdl-31999019
ABSTRACT
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 XylF Bf, F Xyl 2,6-bis(trifluoromethyl)phenyl), a trifluoromethyl group (F MesF Bf, F Mes 2,4,6-tris(trifluoromethyl)phenyl) or a dimethylamino group (p-NMe2 -F XylF Bf, p-NMe2 -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 MesF Bf was also chemically reduced and its radical anion isolated and characterized. Furthermore, all compounds exhibit very long fluorescent lifetimes of about 250â
ns up to 1.6â
µs; however, the underlying mechanisms responsible for this differ. The donor-substituted derivative p-NMe2 -F XylF Bf exhibits thermally activated delayed fluorescence (TADF) from a charge-transfer (CT) state, whereas the F MesF Bf and F XylF Bf borafluorenes exhibit only weakly allowed locally excited (LE) transitions due to their symmetry and low transition-dipole moments.
Texto completo:
1
Banco de datos:
MEDLINE
Idioma:
En
Año:
2020
Tipo del documento:
Article