Theoretical investigation of the nonlinear optical properties of substituted anilines and N,N-dimethylanilines

The nonlinear optical (NLO) properties of a series of anilines and N,N-dimethylanilines are studied with second-order Møller–Plesset perturbation theory (MP2). The effect of solvents on the calculated NLO properties is investigated by considering a wide range of solvent systems within the polarizable continuum model. In order to identify systems with high first-order hyperpolarizability, the effects of four basic variations to the molecules on the calculated NLO properties are studied. The modifications comprise changes to the donor strength (NH2 to N(CH3)2), changes to the acceptor strength (NO2, CN and CHO), variation of additional substituents (H, CH3, Br, OCH3), and changes in the conjugation length. It is found that the first-order hyperpolarizability increases when the compounds have N,N-dimethyl as donor, vinyl nitro group as acceptor at the 4-position, and a methoxy group as substituent at the 2-position.