The solute polarization and structural effects on the nonlinear optical response of based chromone molecules

Abstract

The solute polarization due to solvent is a an electrostatic quantum effect that impacts diverse molecular properties, including the nonlinear optical response of a material. An iterative procedure that allows updating the solute charge distribution in the presence of the solvent is combined with a sequential Monte Carlo / Quantum Mechanics methodology and Density Functional Theory methods to evaluate the nonlinear optical (NLO) response using the hyper Rayleigh scattering (HRS) of a series of chromones recently identified in extit{Chamaecrista diphylla}, an herbaceous plant abundant throughout the Americas and used in folk medicine. From this study, it is determined that from gas to solvent environment, the systems acquire low refractive index ($n$) and an improvement of the first hyperpolarizability ($eta_extrm{HRS}$), signaling potential NLO uses. It is shown that the octupolar contributions ($eta^{J=3}$) superate the dipolar ones ($eta^{J=1}$) and dominate the second-order optical response in both gas and liquid phases, which indicate nontrivial optical materials. Moreover, the solvent environment and structural changes in the periphery can tune significantly the dipolar/octupolar balance, showing a key to control the decoupling between these contributions.