Effect of Molecular Structure on Nonlinear Optical Property in para-Disubstituted Benzylidene-Aniline Derivatives

Forty para-disubstituted benzylidene-aniline derivatives were synthesized, and their second harmonic generation （SHG） effect was measured by the Kurtz powder technique. The effect of the electronic property and the position of the substituents on powder SHG efficiency was studied. It was demonstrated that the compounds bearing with strong electron acceptor and relatively weak electron donor showed quite large SHG efficiency, and that the different position of the same substituents could lead very different SHG values. Theoretical explanation of these phenomena was given in qualitative terms.