The crown thioether 9-[4-(4, 7, 10, 13-tetrathia-1-azacyclopentadecyl] phenyl-N- methylacridinium perchlorate (TCMA) was synthesized and characterized with the aim to verify its ability to interact selectively with metal ions and substantiate the possibility to detect easily the presence of heavy metals in fluid samples. The spectroscopic properties of TCMA, alone and in the presence of metal ions, were therefore studied in polar solvents (MeCN ...