Selective metal ion recognition using a fluorescent 1,8-diquinolylnaphthalene-derived sensor in aqueous solution

The use of anti-1,8-bis(2,2′-diisopropyl-4,4′-diquinolyl)naphthalene, , for metal ion-selective fluorescence recognition has been investigated. Employing CuCl2, ZnCl2, FeCl2, and FeCl3 in fluorescence titration experiments of revealed formation of a bluegreen light emitting bimetallic complex. A dramatic red-shift of the fluorescence maximum of and metal ion-selective quenching was observed in the presence of Cu(II), Fe(II), and Fe(III)chlorides in acetonitrile. By contrast, addition of ZnCl2 was found to result in fluorescence enhancement, whereas Cu(I) did not induce any significant fluorescence change of . The sensor was found to undergo highly ion-selective fluorescence quenching in aqueous solution. Screening of main group and transition metal ions showed excellent selectivity for FeCl3 even in the presence of competing metal ions.