Blue photoluminescence N-substituted poly(4H-benzo[def]carbazole)s

Abstract

N-Alkyl and N-phenyl substituted poly(carbazole)s having a 4,5-ethenylene bridge, poly(4H-benzo[def]carbazole)s, were newly synthesized. Poly(carbazole)s having a 4,5-ethylene bridge were also synthesized for comparison. They were prepared from corresponding dibromo monomers by Ni(0)-catalyzed Yamamoto polycondensation. All the polymers had good solubility in common organic solvents, enough high molecular weights to make thin films, and good thermal stability showing about 400 °C of temperature at 5 wt% loss in TGA. The band gaps of these polymers were in the range of 2.77-3.15 eV which were appropriate for bluish light emissions. The absorption and emission maxima of these polymers in CHCl3 were in the ranges of 361-396 and 419-456 nm, respectively. These polymers showed good fluorescence quantum efficiencies in CHCl3. The energy levels of highest occupied molecular orbital of the poly(benzocarbazole)s were shallower than those of corresponding 4,5-ethylene bridged poly(carbazole)s.

Crystal structure and fluorescence of 1-[8-phenyl-9-(phenylethynyl)-4H-benzo[def]carbazol-4-yl]ethan-1-one

“…For recent background literature on the chemistry of related carbazole-derived compounds and their applications, including syntheses of bioactive carbazoles, see: (Chakraborty et al, 1965;Bondock et al, 2019) and references cited therein. The syntheses of related benzo[def]carbazoles are described by Pocock et al (2021) and Geng et al (2016). For applications of benzo [def]carbazole derivatives, see: Vespa et al (2018), Atakan & Gunbas (2016) and Mys ´liwiec et al (2015).…”

“…The effect of the solvent on absorption and fluorescence bands as well as comparisons with theoretical expectations have been used to estimate the dipole moment of the first excited state. Geng et al (2016) reported the optimized geometry, electron-density distributions, and HOMO and LUMO of carbazole and 4H-benzo[def]carbazole. Changes in the HOMO-LUMO gap (Eg) and the design of molecules for material applications can be realized by comparing frontier molecular orbitals, HOMO and LUMO energy levels, and exploring their electron-density maps.…”

Synthesis and photophysical properties of fluorescent 8,9‐diarylbenzo[def]carbazoles

“…Recently, an approach for the synthesis of 4 H ‐benzo[ def ]carbazole starting from 4‐iodophenanthrene and diaziridinone through C‐H activation and amination has been developed (Scheme 1f) [32]. Kijima et al reported a synthetic strategy, including nitration, reductive ring closure, and dehydrogenation in sequence, to provide benzo[ def ]carbazole (Scheme 1g) from 9,10‐dihydrophenanthrene [33]. Very recently, a direct formation of 4,5‐disubstituted carbazoles through the use of n BuLi–TMEDA for lithiation and annulation with hexafluorobenzene gave the structure of 4 H ‐naphtho[1,2,3,4‐ def ]carbazole (Scheme 1h) [34].…”

“…Furthermore, the solvent effects on absorption and fluorescence bands as well as comparison with theoretical expectations have been used to estimate the dipole moment of the first excited state. In 2016, Geng et al reported the optimized geometry, electron density distributions, and HOMO and LUMO of carbazole and 4 H ‐benzo[ def ]carbazole [33]. One can realize the changes of HOMO‐LUMO gap ( Eg ) and design molecules for material applications by comparing frontier molecular orbitals, HOMO and LUMO energy levels, and exploring their electron density maps.…”

Solvent effects on the morphology and electrical conductivity of a D‐A random copolymer with low band gap

“…Regarding the energy efficiency, polymer light‐emitting diodes (PLEDs) are promising devices that can exhibit acceptable light‐emitting efficiencies and lower electrical consumption than conventional light sources, such as incandescent and fluorescent lamps . Concerning the eco‐friendly and alternative energy production, polymer photovoltaic cells (PSCs) are promising tools to convert directly the absorbed solar radiation into electrical energy, due to their flexibility and straightforward scale‐up production.…”