Discriminative ‘Turn-on’ Detection of Al(3+) and Ga(3+) Ions as Well as Aspartic Acid by Two Fluorescent Chemosensors

In this work, two Schiff-base-based chemosensors L1 and L2 containing electron-rich quinoline and anthracene rings were designed. L1 is AIEE active in a MeOH-H(2)O solvent system while formed aggregates as confirmed by the DLS measurements and fluorescence lifetime studies. The chemosensor L1 was used for the sensitive, selective, and reversible ‘turn-on’ detection of Al(3+) and Ga(3+) ions as well as Aspartic Acid (Asp). Chemosensor L2, an isomer of L1, was able to selectively detect Ga(3+) ion even in the presence of Al(3+) ions and thus was able to discriminate between the two ions. The binding mode of chemosensors with analytes was substantiated through a combination of (1)H NMR spectra, mass spectra, and DFT studies. The ‘turn-on’ nature of fluorescence sensing by the two chemosensors enabled the development of colorimetric detection, filter-paper-based test strips, and polystyrene film-based detection techniques.