Syntheses and characterization of 6,6′-diaryl-9,9′-dialkyl[3,3′]bicarbazoles as materials for electroluminescent devices

C3−C3′ and C6−C6′ Oxidative Couplings of Carbazoles

“…Mostly, 3,3'-bicarbazoles are obtained by chemical oxidation in the presence of FeCl 3 . [14,15] In their report,S iove and Ads [15] study the chemical oxidation of N-alkylcarbazoles by FeCl 3 ,a nd the dimer is exclusively and quantitatively yielded. Ledwith [16] and Simonet [12] note that 9-ethylcarbazole and 9-polyether carbazole in glacial acetic containing perchloric acid also produce the 3,3'-bicarbazoles.…”

“…[39] With 9-alkylcarbazoles as terminating agents, soluble functional polymers with low molecular weights and solution processability can be obtained. Though the synthesis of poly(3,6-carbazole) with oxidizing FeCl 3 has been attempted, [14] only the optical properties of the product have been studied, and detailed structural characterization of the products is incomplete in most cases.T he oxidative reactions of multi-substituted carbazoles can possibly produce their polymers in chloroform in the presenceo fF eCl 3 . [81] The topology of ap olymer as an essential parameter can govern the properties and functions of the polymer.…”

“…In one of the earliest papers, published in 1927, Maitland and Tucker demonstrate that only 3,3′‐bicarbazole is obtained in an acetic acid/sulfuric acid mixture with dichromate present. Mostly, 3,3′‐bicarbazoles are obtained by chemical oxidation in the presence of FeCl 3 . In their report, Siove and Adès study the chemical oxidation of N ‐alkylcarbazoles by FeCl 3 , and the dimer is exclusively and quantitatively yielded.…”

“…In Fe III ‐catalyzed oxidations, C1−C1′ and C2−C2′ couplings are obtained if hydroxy and methyl substituents are introduced onto the carbazole . Furthermore, the synthesis of a high molecular‐weight polymer by oxidative polymerization of 1,4,5,8,9‐pentanmethylcarbazole with FeCl 3 in chloroform has been reported.…”

Carbazole‐Fused Polycyclic Aromatics Enabled by Regioselective Scholl Reactions

“…As first reported in 1920s, [11] oxidative coupling of carbazole in an intermolecular manner gives am ixture of products including 9,9'-bicarbazole,3,3'-bicarbazole and oligomers depending on the reaction conditions,w hile oxidative coupling of 9-alkyl-or 9-arylcarbazoles can produce 3,3'bicarbazole exclusively and quantitatively (Figure 1b). [12,13] On the other hand, intramolecular coupling of carbazole units in aS choll reaction has been rarely studied for synthesis of carbazole-fused polycyclic aromatics.A mong ah andful of such reactions that were documented in research journals [14,15] and patents, [16] the oxidative coupling usually occurred between carbazole and benzene units as exemplified by the recent synthesis of carbazole-fused helicene. [14] Theo nly exception, to the best of our knowledge,i st he synthesis of carbazole-fused coumarin by Venkatakrishnan (Figure 1b), [15] where the oxidative coupling occurs between two carbazole units.U nlike the aromatic bowl (1)s ynthesized through oxidative coupling of carbazole units with Scholl reaction in this study,asimilar aromatic bowl, [3]chrysaorole,w as synthesized by Ste ˛pien ´and co-workers earlier through reductive coupling of prefunctionalized carbazole units as shown in Figure 1c.…”