Two novel Al³⁺ fluorescent-on probes based on thiazole substituted salicylaldehyde and its applications

ABSTRACT

In this study, two structurally similar ‘turn on’ fluorescent probes B1 and B2 with high binding energy with Al³⁺ were synthesised. With new thiazole substituted salicylaldehyde fluorophore, these two hosts also have good selectivity and sensitivity in the detection of Al³⁺ based on the chelating fluorescence-enhancing effect under test conditions. They show an extremely low detection limit, 0.478 nM and 4.04 nM, respectively, with binding constants of 2.34 × 10⁶ M⁻¹ and 1.36 × 10⁶ M⁻¹. A 1:1 binding ratio of dual probes to Al³⁺ was demonstrated by working curves and mass spectrometry. The mechanisms were confirmed by ¹H NMR and DFT calculations, defined that both two compounds combined with Al³⁺ by two oxygen atoms (one in C=O and another in -OH) and one nitrogen atom in -NH group to form triple coordination structure. Further application in test strips, actual soil and traditional Chinese medicine (TCM) suggest probes B1 and B2 have well application prospects in detecting Al³⁺.

GRAPHICAL ABSTRACT

KEYWORDS:

• Al³⁺ detection
• fluorescent probe
• Schiff base
• CHEF mechanism

Acknowledgments

This work is supported by the National Natural Science Foundation of China (51863004) and the Natural Science Foundation of the Guizhou Science and Technology Department (JZ [2018]1077).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/10610278.2023.2270600.