Synthesis and Crystal Growth of Stilbazolium Derivatives for Second-Order Nonlinear Optics



A series of ionic stilbazolium salts with benzenesulfonates with different substituents in the para position have been synthesized. Single crystals of 4-N,N-dimethylamino-4′-N′-methylstilbazolium p-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-N,N-dimethylamino-4′-N′-methylstilbazolium tosylate (DAST).