A novel selective colorimetric chemosensor ANBP ((E)-(2-(((8-hydroxy-2,3,6,7-tetrahydro-1H,5Hpyrido[3,2,1-ij]quinolin-9-yl)methylene)amino)-5-nitrophenyl)(phenyl)methanone), based on the combination of benzophenone group and julolidine chromophore, was synthesized. Sensor ANBP showed rapid colorimetric responses toward Cu²⁺ (pale orange to pink) and F^- (orange to blue). The detection limit by ANBP to Cu²⁺(6.82 µM) was far below WHO guideline value (31.3 µM). Moreover, ANBP could quantify Cu²⁺ in aqueoussamples. 1:1 binding mode between ANBP and Cu²⁺ or F^- was proposed by ESI-mass analyses and Job plots. The remarkable color changes with Cu²⁺ and F ^- resulted from the intramolecular charge transfer (ICT) effect, which was demonstrated by theoretical calculations.

A highly selective colorimetric chemodosimeter ASAD, (E)-2-((4-(diethylamino)-2-hydroxybenzylidene) amino)-5-methoxybenzenesulfonic acid, was readily synthesized and characterized. The probe ASAD could selectively recognize hypochlorite (ClO^-) through an oxidative cleavage of C=N bond with acolor change from yellow to colorless and detected it down to a low concentration of 0.95 μM. Importantly, ASAD could be employed as a practical and efficient optical sensor for ClO− in test strips and water samples. Moreover, the detection process of ASAD to hypochlorite was demonstrated by UV-vis spectroscopy, NMR titration and theoretical calculations.

A novel conjugated Schiff base-based chemosensor DAP, N^¢-((1E,2E)-3-(4-(dimethylamino) phenyl)allylidene)-3-nitrobenzohydrazide, has been synthesized. DAP showed significant selectivity toward mercury ion by color change of pale yellow to orange. Detection limit was 0.11 lM, which is lowerthan the value (2.48 lM) recommended by Health Canada. DAP could recognize and quantify mercury ion in real water samples. The binding mode of DAP and Hg²⁺ was demonstrated, based on Job plot, IR spectra and ESI-MS.