3-(p-nitrophenyl)Coumarin derivatives: Synthesis, linear and nonlinear optical properties

A serie of 3-(p-nitrophenyl)coumarin derivatives have been synthesized, characterized using 1H, 13C NMR and FT-IR spectroscopy and systematically analyzed by means of confocal optical microscopy as well as second harmonic generation (SHG) microscopy. A red shift of photophysical properties and an enhancement of the dipole moment of the dyes after excitation indicate that the emission is mainly caused by an intramolecular charge transfer (ICT). A positive solvatochromism and an increase in the fluorescence intensity have been detected in various solvents. Theoretical calculations based on the DFT and TDDFT theories have been performed in the aim to better understand the correlation between structural, electronic and photophysical properties of the synthesized dyes. The non-linear optical response of all the dyes has been also examined. Efficient NLO responses have been proved and showed a strong dependence on the chemical structure.