Discriminative 'Turn-on' Detection of Al3+ and Ga3+ 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-H₂O 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 Al³⁺ and Ga³⁺ ions as well as Aspartic Acid (Asp). Chemosensor L2, an isomer of L1, was able to selectively detect Ga³⁺ ion even in the presence of Al³⁺ ions and thus was able to discriminate between the two ions. The binding mode of chemosensors with analytes was substantiated through a combination of ¹H 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.

2-Hydroxynaphthalene based acylhydrazone as a turn-on fluorescent chemosensor for Al3+ detection and its real sample applications

Developing high performance fluorescent chemosensor for Al³⁺ detection is highly desirable, due to the excess of Al³⁺ will lead to many diseases. In this paper, a simple 2-hydroxynaphthalene-based fluorescent chemosensor has been synthesized and characterized by different spectroscopic methods. The compound exhibited an "turn-on-type" fluorescent chemosensing for the detection of Al³⁺, which was ascribed to the chelation-enhanced fluorescence (CHEF). The high selectivity and sensitivity of the compound for Al³⁺ were verified by fluorescence spectra in its DMF solution, and the enhancement of fluorescent intensity could be observed by naked-eye from non-fluorescence to green light. The detection limit of the compound for Al³⁺ was found to be 4.22 × 10^-8 M and the stability constant was 4.82 × 10⁴ M^-1. The 1:1 binding stoichiometry of the compound to Al³⁺ was confirmed from the Job's plot based on fluorescence titrations. Additionally, the sensing process of the compound to Al³⁺ was chemically reversible by adding Na₂EDTA. Importantly, the probe was successfully applied to quantitative analysis of Al³⁺ in real drug and potable water samples.

A new salamo-based colorimetric and fluorescent turn-on sensor with aggregation-induced emission for the rapid and highly sensitive detection of cyanide in real samples

A new, simple, and easy-to-manufacture highly selective and sensitive dual-mode sensor A1 with the aggregation-induced emission properties is used for CN⁻ colorimetric and fluorescence detection.