Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C−H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2‐azobiaryls with alkenes to give orange‐red‐fluorescent cinnolino[2,3‐f]phenanthridin‐9‐ium salts and 15H‐cinnolino[2,3‐f]phenanthridin‐9‐ium‐10‐ide is proposed to involve ortho C−H olefination of the 2‐azobiaryl compound with the alkene, intramolecular aza‐Michael addition, concerted metalation–deprotonation (CMD), reductive elimination, and oxidation.
Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C−H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2‐azobiaryls with alkenes to give orange‐red‐fluorescent cinnolino[2,3‐f]phenanthridin‐9‐ium salts and 15H‐cinnolino[2,3‐f]phenanthridin‐9‐ium‐10‐ide is proposed to involve ortho C−H olefination of the 2‐azobiaryl compound with the alkene, intramolecular aza‐Michael addition, concerted metalation–deprotonation (CMD), reductive elimination, and oxidation.
The device efficiency of PM6:Y6-based
nonfullerene organic solar cells is fast advanced recently. To maintain
organic solar cells (OSCs) with high power conversion efficiency over
16% in long-term operation, however, remains a challenge. Here, a
novel non-volatile additive, an open-cage [60]fullerene (8OC60Me), is incorporated into PM6:Y6-based
OSCs for high-performance with high durability. With optimized addition
of 1.0 wt % 8OC60Me, the PCE value of PM6:Y6/8OC60Me OSCs can be promoted to 16.5% from
15.0%. Most strikingly, such a high PCE performance can maintain nearly
100% for over 500 h at room temperature; at an elevated operation
temperature of 80 °C, the PCE can be stabilized above 15.0% after
45 h of operation. Grazing incidence small- and wide- angle X-ray
scattering studies reveal improved orientation and crystallinity of Y6 in a fractal-like network structure of PM6 in PM6:Y6/8OC60Me films under
in situ annealing, parallel to the enhanced electron mobility. Analysis
of charge distributions lines up possible van der Waals interaction
between the thienyl/carbonyl moiety of 8OC60Me and difluorophenyl-based FIC-end groups of Y6. This
result is of great contrast to those devices with the best-selling PC61BM as the additives8OC60Me might be of interest to be incorporated into future Y6-based OSCs for concomitantly improved PCE and excellent
stability.
Background
Benzocarbazole has attracted much attention from scientists in the past few decades for a variety of applications in materials science.
Objective
Herein we report the synthesis and photophysical properties of N‐acyl and N‐free 8,9‐diarylbenzo[def]carbazoles.
Methods
These benzo[def]carbazoles were prepared by Pd(II)‐catalyzed C‐H bond activation and deacetylation as the key steps, and their photophysical properties were studied by measurement of absorption and emission spectra in chloroform at room temperature.
Results
The 8,9‐diarylbenzo[def]carbazoles show lower LUMO energy levels and smaller HOMO/LUMO gap compared to the parent benzo[def]carbazole, and the N‐unprotected 8,9‐diarylbenzo[def]carbazoles show more red‐shifted fluorescent emission compared to the N‐acyl ones. The absorption and emissionmaxima of these 8,9‐diaryl‐substituted benzo[def]carbazoles in CHCl3 were in the ranges of 278–350 and 365–426 nm, respectively, and with quantum yields (ΦF) up to 0.62.
Conclusions
We have demonstrated the photophysical properties of 8,9‐diaryl substituted benzo[def]carbazoles with or without N‐acetyl group. These 8,9‐diaryl substituted benzo[def]carbazoles could be good candidates for the future development of functional organic molecules.
The crystal of the title compound, C60H38N2O2, which crystallizes in the monoclinic space group P21/n, was obtained by thermal evaporation of a 1:1 dichloromethane and hexanes solution of the pure compound. The crystal structure is stabilized by π–π interactions between benzo[def]carbazole moieties and carbonyl–carbonyl interactions between the two acetyl groups.
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