Fluorescent Styryl Dyes from 4-Chloro-2-(Diphenylamino)-1, 3-Thiazole-5-Carbaldehyde—Synthesis, Optical Properties and TDDFT Computations

4-Chloro-2-(diphenylamino)-1,3-thiazole-5-carbaldehyde was reacted with an active methylene compounds, cyanomethyl benzimidazole, cyanomethyl benzothiazole, barbituric acid and Meldrum’s acid under Knoevenagel conditions to give novel push-pull styryl chromophores 8a-8d. The synthesized styryl chromophores were characterized by FT-IR, Mass and 1H NMR spectral analysis. The photophysical characteristics of these styryl chromophores were evaluated. The effect of solvent polarity and viscosity on the absorption and emission properties of these chromophores was studied. The structural, molecular, electronic and photophysical parameters of the push-pull dyes were studied by using density functional theory (DFT) and time dependent density functional theory (TDDFT) computations. The ratio of the ground to the excited state dipole moment of the synthesized novel styryl dyes were calculated by Bakhshiev and Bilot-Kawski correlations.