Synthesis and properties of new π-conjugated imidazole/carbazole structures

New 3-(1H-imidazol-2-yl)-9H-carbazoles and 6,6′-di(1H-imidazol-2-yl)-9H,9′H-3,3′-bicarbazoles have been prepared, starting from 9-ethyl-9H-carbazole-3-carbaldehyde or 9,9′-diethyl-9H,9′H-[3,3′-bicarbazole]-6,6′-dicarbaldehyde through their reactions with 4-methoxyaniline or 4-fluoroaniline, benzil or 2,2′-thenil [1,2-di(thien-2,2′-yl) glyoxal] and ammonium acetate on reflux in glacial acetic acid. The obtained compounds have been shown to demonstrate an effective fluorescence in the blue spectral region, exhibiting quantum yields in the range of 0.08-0.51, depending on their molecular structure and solvent polarity. The nature of the observed absorption spectra has been elucidated by the TDDFT calculations.