A new fluorescent enhancement chemosensor for Al3+ and Fe3+ based on naphthyridine and benzothiazole groups

A novel and easily synthesized compound, N-(2-(2-benzothiazol-2-yl)vinyl-4-methyl-1,8-naphthyrine-7-yl)acetamide (1) based on naphthyridine and benzothiazole group, has been developed as a turn-on fluorescent chemosensor for Al3+ and Fe3+ simultaneously. The absorbance and fluorescent intensities of 1 increased linearly in aqueous solution upon the interaction of 1 with Al3+ or Fe3+. The other co-existing metal ions have no obvious effect on the detection. The Job's plot and the ESI mass spectra indicated the formation of 1:1 complex between 1 and Al3+ or Fe3+. The sensing mechanism was proposed according to the Job's plot, ESI mass spectra, H-1 NMR spectra, and density functional theory (DFT) calculation. The properties of the model compound N-(2-((2-methylbenzothiazol-6-ylimino)methyl)-4-methyl-1,8-naphthyridin-7-yflacetamide (2), which was designed and synthesized in order to prove the sensing mechanism, also verified the proposed sensing mechanism. (C) 2017 Elsevier B.V. All rights reserved.