SYNTHESIS AND SPECTRAL PROPERTIES OF CARBAZOLE-COUMARIN HYBRID DYES

In this study, three carbazole-coumarin hybrid dyes were successfully synthesized, and their UV-vis absorption spectra, fluorescence spectra, and structural properties were investigated. The results indicated that diethyl 12-hexyl-2,9-dioxo-9,12-dihydro-2H-dipyrano[2,3-b:3',2'-h]-carbazole-3,8-dicarboxylate showed a slight red shift of the maximum absorption wavelength, and its fluorescence intensity was above 4000 arb units, about 22 times higher than that of ethyl 10-hexyl-8-hydroxy-2-oxo-2,10-dihydropyrano[2,3-b]carbazole-3-carboxylate and ethyl 10-hexyl-8-(hexyloxy)-2-oxo-2,10-dihydropyrano[2,3-b]carbazole-3-carboxylate in CHCl3. The fluorescence intensity of the three compounds first increases and then decreases with the rise of concentration, and the maximum emission wavelength shows a slight red shift. The stability pH range of diethyl 12-hexyl-2,9-dioxo-9,12-dihydro-2H-dipyrano[2,3-b:3',2'-h]carbazole-3,8-dicarboxylate in THF was 2–10.