Three recently prepared tridentate ligands TPF, TPS and TPT, based on the triazolopyridine-pyridine nucleus possessing fluorescent properties, have been tested as chemosensors for metal ions. A particular response is obtained in the case of ZnTPT+2. The Zn2+ TPT 1 : 1 complex has proved to be an efficient chemosensor for anions especially nitrite and cyanide.