Synthesis and properties of 1, 1-bis (benzo imidazole-2-yl)- 2-(N-ethyl carbazole-3-yl) ethylene

A novel aromatic fused heterocyclic 1, 1-bis(2-benzoimididazole-yl)-2-(N-ethyl carbazole-3-yl)ethylene was synthesized by Vilsmerier-Haack reaction and Knoevenagel reaction using piperdine as catalyst with a yield of 72.53%. Elemental analysis, FT-IR, UV-Vis, 1H NMR, solution fluorescence, solid fluorescence spectroscopy, cyclic voltammetry electrochemical analysis and TG-DTA thermal analysis were used to study its structure, optical properties, electrochemical properties and thermal stability. The results show that this compound has two UV absorption peaks at 290 nm and 375 nm in the dilute solution of DMF, DMSO and DCM, and a blue-green fluorescence emission peak at 470 nm excited by 375 nm. A significant AIE effect was found through solution fluorescence tests with different V(DMSO):V(DCM) mixed solvent of this compound. Solid fluorescence spectroscopy indicate that the product has two excitation peaks at 327 and 436 nm and an emission peak at 484nm with red shift compared to the solution fluorescence. Cyclic voltammetry (CV) was employed to characterize the Eg, EHOMO, and EA of this compound, which are 2.58, 5.43, 2.85 eV, respectively. This result shows that it has good hole transporting ability and good electron transporting capability. TG/DTA analysis shows that the target product possesses good thermal stability.