Experimental and theoretical studies of photophysical properties of N-Substituted iminocoumarins

The photophysical properties of a set of new synthesized iminocoumarins and their N-substituted dyes have been investigated by means of experimental spectroscopy and DFT and TDDFT theoretical calculations. These materials act as push-pull systems consisting of free iminocoumarins and N-substituted by the dicyanovinyl function, that bearing different electron donor and acceptor groups. All the dyes were firstly characterized by NMR and IR experimental spectroscopy. Their photophysical properties are then examined by solid state UV-Vis absorption and fluorescence. Good agreement between experimental and theoretical UV-Vis absorption features was found. The main interests revealed are the substitution and coupling effects on the light absorption and emission characteristics. Attractive and motivating findings were spelled out such a bathochromic shift, gap energy lowering and Stokes shift enhancement. The N-substitution leaded to new red emitting dyes with good stabilities that could be very interesting in optoelectronic devices applications.