New highly fluorescent hybrids (benz)imidazol-2-aminonicotinonitrile and-2-aminoisophthalonitrile: synthesis, characterization, fluorescence study, and theoretical calculations

In this paper, we describe the synthesis of two families of compounds type 2-aminonicotinonitrile and 2-aminoisophthalonitrile bearing a (benz)imidazole moiety. These compounds were prepared via microwave-promoted three-component reaction of 1-(1-methyl-1H-(benz)imidazole-2-yl)ethylidenedicarbonitrile, enolisable ketone, and propanedinitrile under solvent-free conditions. These two classes of compounds were found to be fluorescently active in solution at room temperature showing an intense blue fluorescence with high fluorescent quantum yield, independently of the excitation wavelength. To explore the origin of absorption band in the title compounds, the TD-DFT/B3LYP/TZ2P approach was used to compute electronic excitation energies, and the corresponding oscillator strengths for two compounds. X-ray crystal structures are reported for two compounds. [GRAPHICS] .