Synthesis and characterization of novel butterfly-shaped aryl-substituted indolo[2,3-a]carbazole derivatives

Chemistry and Properties of Indolocarbazoles

“…55 Further bromination is possible with 4.5 equiv NBS in CH 2 Cl 2 /AcOH (1:1), leading to the tetrabrominated product 78 (Scheme 20). 56 In a sequence illustrating some further options in functionalization at the nitrogen atoms leading to the rather elaborate derivative 79 en route toward materials for organic lightemitting diode (OLED) applications, an initial N-arylation of the parent system 1 with iodobenzene in the presence of copper(I) iodide gave the intermediate product 80. Subsequent deprotonation using sodium hydride, followed by nucleophilic displacement of two chlorine atoms in cyanuric chloride (81) afforded the intermediate 82, which eventually provided practical access to the target molecule 79 via a final Suzuki coupling with 4-biphenylboronic acid (83) (Scheme 21).…”

“…As a result of its small singlet−triplet energy level split, balanced charge injection and transporting was realized in an OLED based on the system 165, with excellent values for external quantum efficiency of 24.5%, and power efficiency reaching 64.5 lm W −1 , while a device utilizing compound 166 displayed the longest extrapolated lifetime in the series when measured at a brightness level of 1000 cd m −2 under constant current. 190 Suzuki reactions of brominated indolo [2,3-a]carbazoles have resulted in a series of symmetrically substituted aryl derivatives, 55,56 among which the product 167 in particular was identified as a blue emitter both in solution and as a solid film, displaying a wide HOMO−LUMO energy gap, possessing good thermal stability, solubility, and charge transport ability. 56 Derivatives of the new ring system indolo[2,3-a][1,2,5]thiadiazolo[3,4-c]carbazole ( 22) 50 (section 2.1) have been evaluated as potential materials for optoelectronic applications, such as the halogenated or hydroxylated compounds 168 and 169 (Figure 17).…”

“…190 Suzuki reactions of brominated indolo [2,3-a]carbazoles have resulted in a series of symmetrically substituted aryl derivatives, 55,56 among which the product 167 in particular was identified as a blue emitter both in solution and as a solid film, displaying a wide HOMO−LUMO energy gap, possessing good thermal stability, solubility, and charge transport ability. 56 Derivatives of the new ring system indolo[2,3-a][1,2,5]thiadiazolo[3,4-c]carbazole ( 22) 50 (section 2.1) have been evaluated as potential materials for optoelectronic applications, such as the halogenated or hydroxylated compounds 168 and 169 (Figure 17). The system 168 exhibited characteristics such as a low-lying HOMO level suggesting good air stability, 51 which…”

“…Scheme 13. Synthesis of an Indolo[2,3-a]carbazole from a 2,2′-Biindolyl Derivative En Route to the Alkaloid Calothrixin B(56) …”

Tuning the Photophysical and Electroluminescence Properties in Asymmetrically Tetrasubstituted Bipolar Carbazoles by Functional Group Disposition

“…9 H -Carbazole is one of the most preferred synthons for material chemists and is adopted as a promising building block to construct functional materials for organic electronics owing to its commendable properties such as rigid molecular structure, amorphous nature, high thermal and photochemical stability, good hole-transporting ability, and high triplet energy (∼2.9 eV). − Consequently, innumerable oligo-/polycarbazoles have been documented as representative benchmark materials in OLEDs, OFETs, OPVs, and in fluorescent sensors. ,,− Carbazole can be easily functionalized on C1, C2, C3, C6, C7, C8, and N -positions. To date, majority of the literature is focused on trifunctionalization (C3, C6 and N - and C2, C7 and N -) of the carbazole core. − Yet, relatively less amounts of C1 and C8-functionalized (ortho- to carbazole nitrogen) carbazoles are known in the literature, when C3 and C6 positions are protected with alkyl units. − Recently, polyfunctionalized carbazoles (C1, C3 and C6-tri and C1, C3, C6 and C8-tetra) were explored and found to exhibit decent device performances in electroluminescent (EL) devices. − However, C2, C3 and C7-tri- and C2, C3, C6 and C7-tetra-substituted carbazoles are relatively less explored when compared with the aforementioned functionalizations due to the requirement of tedious indirect synthetic protocols. − Although the structure–function relationships of symmetrically functionalized polysubstituted carbazoles featuring different electron-rich chromophores are well furnished in the literature, − same on unsymmetrically polyfunctionalized bipolar carbazoles containing donor and acceptor units with differen...…”