Abstract 1-Alkyl-2-[4-(diethylamino) styryl] pyridinium salts showed fluorescence maxima at around 650 nm in the solid state depending on the alkyl group and counter anion. 1-Butyl-2- [4-(diethylamino) styryl] pyridinium bis (perfluorobutylsulfonyl) imide exhibited the fluorescence maximum at 652 nm with the highest quantum yield 0.16 in the crystalline form. The single X-ray crystallography suggests that this compound exhibits isolated dimer-type ...
