| Summary: | 博士 === 國立清華大學 === 化學系 === 88 === In accordance with the concept of conjugation, we have
developed a new class of p-aminoisocondensed heteroaromatic
pyrroles. These compounds showed interesting photophysical
and electrochemical properties.
By our method of retro-malonate addition reaction, we have
synthesized four series of p-aminoisocondensed heteroaromatic
pyrroles successfully, namely, (1) p-aminophenylthieno[2,3-c]
pyrroles 74 ~ 77 and 80. (2) isoindoles 84 ~ 87 and 90 . (3)
tert-butyl 2-(4-aminophenyl)-2,4-dihydropyrrolo[3,4-b]indole-
4-carboxylates 95 ~ 98. (4) methyl 2-(4-aminophenyl)-2,4-
dihydropyrrolo[3,4-b]indole-4-carboxylates 102 ~ 105.
The differential scanning calorimetry (DSC) measurements
revealed a glass transition temperature of 193.6 ℃ for
compound 74, 147.4 ℃ for compound 98, 29.8 ℃ for compound
102, 26.1 ℃ for compound 103, 30.7 ℃ for compound 104,and
52℃ for compound 105,but compound 95 ~ 98 started degrading
above melt point. These compounds showed good fluorescence
properties both in solid and solution states.The fluorescence
wavelengths located within 360 ~ 500 nm ( blue-green ) in
solution state, and within 340 ~ 460 nm(blue) in solid state.
The -NR2 group at the para-position of the phenyl substitient
play an important role in finetuning both the intensity of
andfluorescence of p-aminoisocondensed heteroaromaticpyrroles.
By cyclic voltammetry (CV)measurements, we have observed that
the electrochemicalbehavior of compounds 74, 95, 96, 98, and
102 ~ 104 was reversible. According to the redox potential
position of CV and the onset absorption position of UV-VIS
spectra, the HOMO, LUMO, and energy gap ( Eg ) for these
compounds, Alq3, PBD, TPBI, and NPB were estimated using the
energy level of ferrocene as a reference ( 4.8 eV below the
vacuum level).
In organic light emitting diodes application, compounds 86
and 96 were not good emitters. The lifetimes of devices made
form these c ompounds were too short (about 5 ~ 20 sec ).
Compounds 75, 76, and 86 were not useful as hole transport
material due to their poor electrochemical properties. Using
compound 96 as a hole transport material and Alq3 and PBD as
electron transport material, the devices do not show a good
I-V curve.
|
|---|
