Synthesis, Spectral Studies and Quantum-Chemical Investigations on the Powerful Fluorophores: Imidazo[4,5-a]acridines.

The new 3H-imidazo[4,5-a]acridine-11-carbonitriles were prepared from the reaction of 1-alkyl-5-nitro-1H-benzoimidazoles with 2-(4-methoxyphenyl)acetonitrile and benzyl cyanide by nucleophilic substitution of hydrogen in high yields. Physical spectral and analytical data have confirmed the structures of the synthesized dyes. The optical and solvatochromic properties of these compounds were investigated and the results showed that they show very interesting photophysical properties. Density functional theory (DFT) calculations of fluorescent dyes were performed to provide the optimized geometries and relevant frontier orbitals. Furthermore, intra- and intermolecular interactions in fluorescent imidazo[4,5-a]acridines were evaluated by AIM (Atoms in Molecules) analysis.