An electron-rich phthalocyanine-thiophene-phthalocyanine triad 3 (Pc-triad 3), newly synthesized, can function as a highly selective chemosensor against picric acid (PA). Pc-triad 3 showed efficient and selective fluorescence quenching towards PA, during which a photoinduced electron transfer (PET) complex arose from the electron-rich pendant Pc rings of 3 to the PA reagents.