6 research outputs found
Me3Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines
A simple and efficient protocol for the construction of 1-aminoisoquinolines was achieved by treating 2-(2-oxo-2- phenylethyl)benzonitriles with amines in the presence of Me 3 Al. The reaction proceeds via a domino nucleophilic addition with subsequent intramolecular cyclisation. This method provides a wide variety of substituted 1-aminoisoquinolines with good func- tional group tolerance. Furthermore, the synthetic utility of this protocol was demonstrated in the successful synthesis of the anti- tumor agent CWJ-a-5 in gram scale
Fine‐Tuning the Physicochemical and Electroluminescence Properties of Multiply‐Substituted Bipolar Carbazoles by Functional Group Juggling
Tuning the Photophysical and Electroluminescence Properties in Asymmetrically Tetrasubstituted Bipolar Carbazoles by Functional Group Disposition
Carbazoles
decorated with both donor and acceptor fragments offer a classical
way to optimize bipolar functional properties. In this work, a series
of carbazoles featuring triphenylamine donors and cyano acceptors
are synthesized and their structure–property relationship is
studied. The effects of connectivity and the chromophore number density
on photophysical and electroluminescence properties are investigated.
The position of the triphenylamine donor on the 3,6-dicyanocarbazole
nucleus significantly affected the photophysical and electroluminescence
properties. The dye possessing triphenylamine on C2 and C7 displayed
a red shift in absorption when compared with the structural analogue
with triphenylamine tethered to C1 and C8. The emission wavelength
of the dyes are tunable from blue to green, by altering the position
of triphenylamine and cyano substituents. All of the dyes exhibited
positive solvatochromism in emission, attributable to the photoinduced
intramolecular charge transfer from the triphenylamine donor to the
cyano acceptor. However, the extent of charge transfer and hybridization
of local and charge-transfer-excited states is highly dependent on
the position of triphenylamine and cyano groups on the carbazole nucleus.
Dyes containing cyano substituents at C2 and C7 showed a prolonged
excited state lifetime, broad emission, and large Stokes shifts, indicating
the presence of a higher charge transfer component in the excited
state. The dyes displayed exceptional thermal stability with the onset
decomposition temperature (10% weight loss) > 350 °C. Electrochemical
measurements revealed low oxidation potential for dyes containing
triphenylamine at C3 and/or C6. Addition of a cyano acceptor on carbazole
led to the stabilization of lowest unoccupied molecular orbital. Furthermore,
the materials were tested as emitting dopants in solution-processable
multilayer organic light emitting diodes and found to display deep-blue/sky-blue
electroluminescence with external quantum efficiency as high as 6.5%
for a deep-blue emitter (CIE<i>y</i> ∼ 0.06)