Synthesis of a new Schiff base probe: Crystal structure, spectral properties, understanding and prospect

Among the various Schiff bases, those containing 2,4-diaminotoluene as a primary amine and 2-hydroxy-4-methoxybenzaldehyde as a carbonyl compound are new and deserve special attention because their logical spectral properties find application in analytical chemistry as a smart probe. The new Schiff base has been synthesized to its pure crystalline form. It is characterized by single-crystal XRD, FT-IR, NMR, TGA, and mass spectrometry. We have studied the spectral properties of the Schiff base and its aluminium adduct by UV-vis and fluorescence spectroscopy and rationalized them by computational analysis. The Job's plot and mass spectrometry indicate the 1:1 binding ratio between the ligand and the Al³⁺ ion. The suitable binding constant value (8.329×10³ M^–1) leads to the development of Al³⁺ sensation by the Schiff base. The sensor has an appreciably low limit of detection value of 7.638×10^–9(M), i.e., 0.00163 ppm for Al³⁺. The logical behaviour of the probe (NAND-type molecular logic gate with two inputs, Al³⁺ and EDTA) leads to the development of a renewable aluminium testing kit.

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