Single crystals of stilbazolium derivatives for second-order nonlinear optics

A series of ionic stilbazolium salts with benzenesuffonates with different substituents in the para position have been synthesized. Single crystals of 4-NN-dimethylamino-4'-N'-methylstilbazoliump-methoxybenzenesulfonate (DSMOS) were successfully grown in methanol solution by slow cooling. X-ray studies revealed that DSMOS crystallized in the triclinic space group P1 with its molecular dipoles perfectly aligned in one direction-favorable for large nonlinear optical and electro-optical effects. Kurtz powder tests revealed a large powder second-harmonic generation efficiency that is similar to that of the well-studied 4-NN-dimethylamino-4'-N-methylstilbazolium tosylate (DAST).