Synthesis and photophysical properties of fluorescent 8,9‐diarylbenzocarbazoles

BackgroundBenzocarbazole has attracted much attention from scientists in the past few decades for a variety of applications in materials science.ObjectiveHerein we report the synthesis and photophysical properties of N‐acyl and N‐free 8,9‐diarylbenzo[def]carbazoles.MethodsThese 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.ResultsThe 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.ConclusionsWe 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.