Novel scorpion-like carbazole derivatives: Synthesis, characterization, mechanochromism and aggregation-induced emission

摘要

A series of nitrophenyl substituted carbazole derivatives [9-(4-nitrophenyl)-9H-carbazole (1), 3,9-bis(4-nitrophenyl)-9H-carbazole (2), 9-methyl-3,6-bis(4-nitrophenyl)-9H-carbazole (3), 9-ethyl-3,6-bis(4-nitrophenyl)9H-carbazole (4), 9-butyl-3,6-bis(4-nitrophenyl)-9H-carbazole (5), 9-hexyl-3,6-bis(4-nitrophenyl)-9H-carbazole (6)] bearing D-pi-A systems were prepared and their photophysical properties were investigated comparatively and systematically. Compounds 1, 2, 5 and 6 exhibited obvious aggregation-induced emission properties in DMF/water mixtures and aggregate formation endued them bright luminescence. The elongation of the N-substituted alkyl chains leads to an obvious hypochromatic shift of solid-state fluorescence for compounds 3-6. Specifically, compound 6 showed mechanochromic property involving a reversible interconversion between crystalline form and amorphous phase by mechanical grinding and dichloromethane vapor fuming.