Synthesis, optical, and electrochemical properties of 2,3-diphenyl-10H-indeno[1,2-g]quinoxaline, 15H-dibenzo[a,c]indeno[1,2-i]phenazine, and 15H-indeno[1,2-i]phenanthro[4,5-abc]phenazine derivatives

Abstract

A series of 2,3-diphenyl-10H-indeno[1,2-g]quinoxaline, 15H-dibenzo[a,c]indeno[1,2-i]phenazine, and 15H-indeno[1,2-i]phenanthro[4,5-abc]phenazine derivatives containing different terminal aromatic units such as phenyl, phenylethynyl, naphthyl, anthryl, pyrenyl, or 4-(diphenylamino)phenyl have been synthesized by employing palladium-catalyzed C–C cross-coupling reactions in good yields. All of the target compounds were characterized using 1H NMR, 13C NMR, high resolution MS, optical absorption, and emission spectra. Even though the electronic absorption spectra of the compounds were influenced by the nature of the peripheral arenes, the emission spectra indicated close similarity for the excited states in the 15H-indeno[1,2-i]phenanthro[4,5-abc]phenazine series compounds. Most compounds possess a medium fluorescence-emitting ability with φFL values in the region of 0.40–0.71 and displayed blue, green, yellow, or red emission depending on the nature of the whole molecule. Structure–optical behavior characteristics and further details of the electronic properties from cyclic voltammetry measurements and theoretical calculations were discussed.