A novel stilbene-based organic dye with trans-cis isomer, polymorphism and aggregation-induced emission behavior.

Cis-trans isomer and polymorphism of 9-(4-(4-nitrostyryl)phenyl)-9H-carbzole (Dye 1 ) were obtained unexpectedly. Each isomer has two polymorphs, which was characterized by X-ray single crystal diffraction. Polymorphs T1 and T2 are trans -configuration and both crystallize in monoclinic space group P 21/c. Polymorphs C1 and C2 are cis -configuration and crystallize in triclinic space group P -1 and monoclinic space group P 21/c, respectively. Trans -isomer shows better stability and higher density than that of cis -isomer, but cis -isomer displays better solubility than that of trans -isomer. The molecular structures and packing arrangements of the four kinds of crystals show different features. The twisted conformation of cis -isomer effectively avoids π-π interactions and close packing. Both the trans and cis isomers show remarkable aggregation-induced emission effect in the acetonitrile/water mixture. In addition, fluorescence cell imaging experiment proves the potential application of the two isomers of dye 1 . [ABSTRACT FROM AUTHOR]