A smart chemosensor with different response mechanisms to multi-analytes: Chromogenic and fluorogenic recognition of Cu2+, Fe3+, and Zn2+. (May 2023) - Li, Da
Abstract: Single-component sensors that can detect multiple analytes have drawn great research attentions. Herein, a smart chemosensor TPBS that can recognize multiple targets was developed by connecting triphenylamine with benzothiazole via an imine link. The N atoms with lone pair electrons on the flexible imine link served as potential coordination sites to allow for variations in charge transfer and molecular configurations. In CH3 CN, TPBS simultaneously achieved the recognition of Cu 2+ through a chromogenic response (colorless to red) via ligand-metal charge transfer, and the recognition of Fe 3+ through a "turn-on" fluorogenic response (non-emission to blue) via the chelation-enhanced fluorescence effect. In aqueous solution, TPBS recognized Zn 2+ via a "turn-on" fluorogenic response (non-emission to green) based on the aggregation-induced emission behavior. The detection limits were as low as 0.45 μM, 3.24 μM, and 3.22 μM for Cu 2+, Fe 3+, and Zn 2+, respectively. A 1:1 binding stoichiometry and exact complex modes between TPBS and the target metal ions were deduced using Job's plot and FT-IR analyses. Both experiments and theoretical calculations supported the deduced coordination mechanisms. The ability of TPBS to recognize Cu 2+, Fe 3+, and Zn 2+ was then tested in real-life water samples and through on-site detection of Zn 2+ using test strips. Graphical abstract: Image 1 Highlights: A new triphenylamine-based multi-analytes chemosensor TPBS with low detection limit is reported. TPBS achieved detection of Cu 2+ by a chromogenic response from colourless to red via LMCT in CH3 CN. TPBS achieved detection of Fe 3+ by blue emission turn-on via CHEF in CH3 CN. TPBS achieved detection of Zn 2+ by green emission turn-on via AIE behaviour in aqueous solution.