PyridineN‐oxide–BF2CF3 and –BF2C2F5 complexes and their derivatives were synthesized. Most of the complexes show fluorescence both in solution and in the solid state. By expanding the π‐conjugated skeleton, the color of the fluorescence could be changed dramatically. A fluorophore with a high solvent dependency could also be produced. Since such compounds can be synthesized on a gram scale in high