| Abstract
| - Two novel 2,7-linked N-alkylcarbazole trimers have been synthesized by Suzuki cross coupling and compared to the analogous fluorene trimers. The 2,7-linked carbazole trimers exhibit bright blue fluorescence, which is unusual for carbazole oligomers and polymers.
- In this paper we present a new synthesis for N-alkylated 2,7-dibromocarbazoles, fromwhich 2,7-linked carbazole trimers have been synthesized by Suzuki cross coupling. Thecompounds were characterized regarding their thermal, optical, and electrochemicalproperties and compared to analogous fluorene trimers, which also have been prepared bySuzuki reactions. The carbazole and fluorene trimers exhibit thermal stabilities of morethan 300 °C and are able to form molecular glasses. Only one of the carbazole trimers iscrystalline. Both carbazole and fluorene trimers exhibit a bright blue fluorescence with amaximum at 393 nm and show similar absorption characteristics. Cyclovoltammetricexperiments revealed the electrochemical stability of the fluorene trimers. Their HOMOand LUMO levels are at −5.6 and −2.5 eV, respectively. In contrast to the fluorenes, the2,7-linked carbazole trimers showed nonreversible oxidations in the CV experiments.
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