A novel colorimetric-fluorescent probe for Al3+ and the resultant complex for F- and its applications in cell imaging

A novel quinoline-based Schiff-base probe QL had been synthesized, which could sequentially monitor Al3+ and F- in MeOH-H2O solution (v/v=8/1, 0.01 M, HEPES buffer, pH=7.3). The probe QL expressed a high selective and sensitive "OFF-ON-OFF" fluorescent response for Al3+ and F- (excitation at 460 nm and emission at 530 nm) accompanying visible color changed, which was ascribed to intramolecular charge transfer (ICT) process and chelation-enhanced fluorescence (CHEF) mechanism. The binding stoichiometry of QL with Al3+ was 2:1 counting on Job's plot and HRMS, while F- could pull Al3+ to depart from the complexation 2QL-Al3+ and released free QL. The limit of detections of probe QL for Al3+ and F-ions were calculated to be 0.10 mu M and 0.50 mu M. The H-1 NMR experiments and density functional theory (DFT) calculations were carried out to further prove the binding mode between QL and Al3+. Furthermore, fluorescence imaging studies demonstrated that the probe QL was low cytotoxicity and could be applied to detect Al3+ and F- in living PC12cells. (C) 2019 Elsevier B.V. All rights reserved.