A dual fluorescence probe for Zn2+ and Al3+ through differentially response and bioimaging in living cells

A novel Schiff base fluorescent probe 7-Hydroxy-8-(((2-(hydroxymethyl)quinolin-8-yl)imino)methyl)-coumarin (XL) consist of formylcoumarin and aminoquinoline moieties was synthesized for dual detection of Zn2+ and Al3+ ions. Probe XL exhibited high selective and sensitive response towards Zn2+ and Al3+ ions through different color changes and significant fluorescence turn-on response (270 fold higher for Zn2+ and 230 fold higher for Al3+) in MeOH-H2O (4/1, v/v) over other cations, with detection limits (LOD) as low as 3.75 x 10(-8) and 1.14 x 10(-8) M, respectively. Moreover, probe XL exhibited preferential selectivity for Al3+ through displacing Zn2+ from the XL-Zn2+ complex by ligand-to-ligand transfer process. The binding mechanism of intramolecular charge transfer (ICT) were proposed from fluorescence and UV-vis titrations, Job's plot, H-1 NMR titration, HRMS and DFT calculations. The probe was proven to be suitable for actual samples detection of Zn2+ and Al3+ ions. The complex XL-Zn2+ and XL-Al3+ exhibited dramatic fluorescent "turn-off" properties for PPi and PPi/F- respectively through snatching metal ions and released free XL. Moreover, probe XL showed low biotoxicity and sequentially "off-on-off" fluorescent bio-imaging of Zn2+/Al3+ and PPi/F- in PC12 cells. (C) 2019 Elsevier B.V. All rights reserved.