The synthesis and optical properties of novel fluorescent iminocoumarins and bis-iminocoumarins: Investigations in the series of urea derivatives

The condensation of 3-cyano-7-diethylamino-iminocoumarin with various isocyanates and diisocyanates as C-electrophiles gave a new series of N-substituted iminocoumarins and bis-iminocoumarins. The ten compounds obtained were characterized using IR, 1H NMR, 13C NMR, elemental analysis and mass spectrometry. Their optical properties, studied in dichloromethane by UV/vis absorption and fluorescence spectroscopy, were found to depend strongly upon the nature of the substituent borne by the imino group. For the sake of comparison, the optical properties of selected compounds were also analyzed in ethanol. Of the iminocoumarins studied, the alkylurea derivatives displayed the most interesting spectroscopic characteristics and may be of potential use as novel fluorescent probes in media of various polarity.