Synthesis and spectral properties of coumarins derivatives fluorescence emitters: Experiment and DFT/TDDFT calculations

Highly fluorescence, 3-(p-nitrophenyl)-7-diethylamino and 3-cyano-7-diethylaminocoumarin, iminocoumarins derivatives differing by the position of substituents and acceptors groups were investigated and characterized using H-1, C-13 NMR and FT-IR spectroscopy analysis. These dyes were photophysically characterized and the effects of the substituents investigated. As a result, efficient charge transfer was maintained through the molecule. UV visible absorption and fluorescence spectra of these dyes became shifted to longer wavelengths upon substitution at 7-position and depend on the attractor group. However, tradeoffs in spectral shifts were observed when two donor attractor electron groups such as N-diethyl substitue at position 7 and nitrophenyl in position 3, respectively. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure and optical properties of the investigated molecule.