Abstract: Second-order polarizabilities of 1,3-diphenl-2-pyrazoline and 1-(4’-nitrophenyl)-3-phenyl -2-pyrazoline have been measured by a solvarochromic method. The results show that electro-withdrawing substituent (such as nitro group) at the phenyl group linked with the C-3 atom gives rise to large second order polarizabiliy. It is accordant with the results of quantum mechanics calculation. The results also show that the studied substituted pyrazolines can be applied as a kind of high efficiency second order harmonic generation (SHG) materials.

Key words: nonlinear optical materials, second harmonic generation, pyrazoline compounds, solvatochromism