Synthesis, Spectral Studies, and Quantum Chemical Investigations of a New Violet Dye and a Fluorescent Heterocyclic System

The new violet dye 3-(hydroxynnino)imidazo[1,2-a]pyridin-2(3H)-ylidene)-2-(naphthalen-l-yl) acetonitrile was synthesized by reaction of 3-nitro-imidazo[1,2-c]pyridine with 1-naphthylacetonitrile. Cyclization of the latter compound in pyridine led to the formation of new fluorescent heterocyclic system benzo[Apyrido[2',1' :2,3] imidazo[4,5-b]quinoline. The structural assignments of the new compounds were based on their spectral and microanalytical data. The optical and solvatochromic properties of the compounds were investigated, and the results showed that they display interesting photophysical properties such as high values of extinction coefficient and fluorescence quantum yield. Moreover, the density functional theory (DFT) calculations were employed to gain a deeper insight into the geometry and relevant frontier orbitals of the compounds. Calculated electronic absorption spectra were also obtained by the time-dependent DFT method. [GRAPHICS] .