Tuning the nonlinear optical properties by engineering donor-acceptor configurations in nitrochalone derivatives

Development of tunable photonic devices having molecular dimensions is an active research area in nonlinear optics which continues to evolve and impact many technologies. Here, we demonstrate the tailoring of nonlinear optical properties of nitrochalcone derivatives by engineering the donor-acceptor configurations on either end of the molecules, to control the intramolecular charge transfer process. The central pi-bridge in chalcones provides delocalized electrons which lead to the nonlinear polarizability observed in these molecules. Optical nonlinearity is studied by means of second harmonic generation (SHG) and open aperture Z-scan measurements. Samples show optical limiting behaviour in the nanosecond excitation regime due to excited state absorption (ESA) and two-photon absorption (2PA) phenomena. Our study highlights the importance of structure-property correlations in molecular designs.