In this paper, two novel fluorescent chemosensors, naphthalene-armed benzoaza-15-crown-5 (3) and 5-chloroquinoline-armed benzoaza-15-crown-5 (4), were synthesized, and their structures were confirmed by ¹H NMR and elementary analysis. The selective sensibility of crown ether 3 and 4 for K^＋, Ca^2＋, Mg^2＋, Pb^2＋, Co^2＋, Ni^2＋, Mn^2＋, Cu^2＋, Zn^2＋, Cd^2＋and Hg^2＋ were examined respectively by ultraviolet spectroscopy and fluorescence spectrum method in ethanol. The obtained results indicate that crown ether 3 exhibits significant sensitivity only to Cu^2＋ ion, which may be due to a typical radiation energy transfer process. Crown ether 4 shows special sensitivity for Ni^2＋, Co^2＋, Cu^2＋ and Mn^2＋ ions, and the gradual increasing amount of the metal ions leads to the changes of the fluorescence of 4 in the quenching after the enhancement. That fluorescence enhancement may be due to the suppression of the weak photo-induced electron transfer (PET) operating from the nearby nitrogen atom of the crown ether ring to the quinoline fluorophore|and fluorescence quenching may be due to the mechanism of the crown ether ring cooperated with the quinoline group chelating to the metal ion. The contrast between the structure-property relationship of crown ether 3 and that of crown ether 4 indicates that the luminophor group of the sensor has great effect on the metal ion-selectivity.

Key words: fluorescent azacrown ether, synthesis, metal ion, selectivity, chemosensor