Second- and third-order nonlinear optical properties of mono-substituted terpenoid-like chalcones

Organic molecules exhibiting second and third-order nonlinear optical properties (NLOP) allow several applications in optics and photonics. Among the class of organic compounds, terpenoid-like chalcones derivatives constitute a suitable choice as nonlinear optical materials, given the possibility of obtaining a wide range of compounds that can be used in biophotonic applications. In this way, here we present a study of the first-order molecular hyperpolarizability and the two-photon absorption (2PA) cross-section of several terpenoid-like chalcones derivatives, aiming for applications in the therapeutic window. The 2PA spectra were evaluated employing the femtosecond tunable Z-Scan technique from 480 nm to 850 nm, and the first hyperpolarizability was determined at 1064 nm using the Hyper-Rayleigh scattering (HRS) technique. Moreover, the first-order molecular hyperpolarizability and the 2PA spectra were modeled by the sum-over-states (SOS) approach and undamped phenomenological model, respectively, providing new insights into the properties and compounds structure relationship. Results showed that substituent features, such as electron-donating or withdrawing ability, were associated with the 2PA cross-section magnitude. Regarding HRS results, it was possible to compare the difference of state dipole moment from both approaches, combining two experimental mutes to determine photophysical parameters of non-fluorescent compounds, revealing the structure-relationship aiming the increase of the NLOP at the near-infrared region.