An AIE dynamic a highly selective and expeditious benzothiazole-pyrazine based colorimetric chemosensor for Ni2+and fluorogenic chemosensor for Cu2+ and Al3+ detection.

[Display omitted] • A Benzothiazole functionalized pyrazine sensor BPA shows ratiometric recognition for the Cu2+ and Al3+ ions. • The BPA sensor has a low detection limit and can identify Ni2+ ions with the naked eye. • The sensing mechanism was confirmed using an FT-IR, HRMS, and DFT experiment. • Employing paper strip detection techniques, on-site detection of Ni2+, Cu2+, and Al3+ was successfully tested. Considerable research focus has been devoted to the advancement of single-component sensors that can identify several analytes. In this regard, a complex chemosensor called BPA was created by building an imine link between benzothiazole and pyrazine. On the flexible imine link, the nitrogen atoms with lone pair electrons were arranged as possible coordination sites to enable changes in molecular configurations and charge transfer. In the aqueous acetonitrile environment, BPA displayed the discriminative identification of Ni2+ by a chromogenic response (color transition from colorless to yellow) and a fluorescence "decreasing" response for Cu2+ via ligand–metal charge transfer. Additionally, BPA exhibited recognition of Al3+ through a "turn-on" fluorogenic response facilitated by the chelation-enhanced fluorescence effect. The detection limits for Ni2+, Al3+, and Cu2+ were remarkably low, measuring 5.19 nM, 16 nM, and 214 nM, respectively. A 1:1 binding stoichiometry and precise complex modes between BPA and the target metal ions were successfully determined using extensive investigations, which encompassed the utilization of Job's plot, mass spectra, NMR, and DFT analysis. The deduced coordination mechanisms were corroborated by computational and experimental methodologies. BPA 's potential practical uses were demonstrated by subsequently evaluating its ability to identify Ni2+, Al3+, and Cu2+ in actual water samples and validating its performance on-site using test strips. [ABSTRACT FROM AUTHOR]