Title
Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3-b:3’,2’- e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties
Author
Yuhei Itai, Yuji Nishii, Patrycja Stachelek, Przemyslaw Data, Youhei Takeda, Satoshi Minakata, Masahiro Miura
Year
2018
Journal
The Journal of Organic Chemistry
Abstract
A series of bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys) bearing a chlorine functionality have been efficiently synthesized through a Pd-catalyzed double oxidative intramolecular C–H/C–H coupling of mono-chlorinated 2,6-diaryloxypyridines. The subsequent Buchwald-Hartwig amination of the chlorinated BBZFPys allowed for the access to a new class of donor-acceptor (D-A) π-conjugated compounds that comprise of BBZFPy as an electron-acceptor (A) and diarylamines as a donor (D) units. The investigation of the steady-state photophysical properties of the prepared D-A compounds revealed that they are emissive in both of solution and solid states in blue-to-green color region. The singlet-triplet energy splitting (DEST) was found much smaller than that of substituent- free BBZFPy (0.70 eV), ranging from 0.01 to 0.56 eV. The time-resolved spectroscopy revealed that the D-A compounds comprising of a bis(tert-butyl)carbazole as the D and CF3-attached BBZFPy as the A showed delayed fluorescence (DF) in a non-polar matrix host material (Zeonex®), while in a polar matrix (DPEPO), room-temperature phosphorescence (RTP) was faintly observed. Furthermore, organic light-emitting diodes (OLEDs) fabricated with the D-A compounds as a blue-emitter showed a moderate external quantum efficiencies (EQEs) up to 1.5%.
Full Article
Instrument
FP-8500
Keywords
Fluorescence, Photoluminescence, Quantum yield, Optical properties, Phosphorescence, Solid state, Organic chemistry, Materials