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

Abstract 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 P 1 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).