Experimental and theoretical investigation of first hyperpolarizability in aminophenols

This work reports theoretical and experimental studies on the first hyperpolarizability (β) of aminophenols, evaluating the influence of the NH2 group position relative to the OH group on the hyperpolarizability. A new extension of hyper-Rayleigh scattering technique using picosecond pulse trains was employed to obtain the experimental absolute values of (β). The theoretical static β(0) values were calculated using AM1 method implemented in the AMPAC program. The theoretical and experimental data show a clear dependence between β and the relative position of the electron donor (D) and acceptor (A) groups, presenting the 2-aminophenol the higher values. Moreover, calculations show excellent qualitative agreement between theoretical and experimental data, which are improved when the simulations considering the solvated molecule in a combination of discrete solvent molecules interacting with the solute and the application of continuous dielectric model. Besides, the study indicates that the experimental hyperpolarizabilities seem to be a property of the solute-solvation shell system. These facts have affirmed that the theoretical approach employed can be successfully used to foresee the variation in β due to modifications in the D/A position. Moreover, a theoretical study of the ground state absorption is performed and compared with experimental data.