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摘要
A new coumarin based Schiff-base chemosensor, (E)-7-(((8-hydroxyquinoline-2-yl)methylene)amino)-4-(trifluoromethyl)-2H-chromen-2-one (H12L) was designed and synthesized. This chemosensor was evaluated as a colorimetric sensor for Fe3+ and fluorescence "turn on-off" response to Zn2+ and Cu2+ using steady-state absorption and fluorescence spectroscopy. In the presence of Fe3+ and Zn2+, the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other surveyed metal ions, with a distinct color change which provides naked eye detection. However, in the presence of Cu2+, it also exhibits quenching of fluorescence emission intensity which may be due to the paramagnetic nature of Cu2+ ions. The stoichiometric ratio and binding constant were calculated using the Benesi-Hildebrand relation and Job's plot analyses, giving 1 : 1 stoichiometry. The interaction and binding nature of H12L with Zn2+ ions was further confirmed by H-1 NMR titration assay and ESI-mass spectral analysis. The reversibility of H12L was also studied using EDTA as a chelating ligand. Moreover, H12L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn2+ (IN1) and Cu2+ (IN2) and (ii) Zn2+ (IN1) and EDTA (IN2) and the emission as output. Again, an IMPLICATION logic gate is obtained with Cu2+ and EDTA as chemical inputs and emission as the output mode. Both H12L and metalcomplexes were optimized using density functional theory and vibrational frequency calculations confirm that both are at local minima on the potential energy surfaces. The corresponding energy difference between the HOMOs and LUMOs of H12L, Zn-complex and Cu-complex are found to be 2.11, 0.81 and 0.17 eV, respectively.
- 出版日期2016
