Novel fluorescent probes for sequential detection of Cu2+ and citrate anion and application in living cell imaging.

Abstract Three novel fluorescent probes (L1, L2 and L3) derived from 2-hydroxyphenyl-4-chloromethyloxazole 8-ydroxyquinaldine were designed and synthesized. The probes showed highly selectively and sensitivity towards Cu2+ ion through "turn off" response in DMF/H 2 O solution (v/v = 1/1, 0.01 M, Tris-HCl buffer, pH 7.30). The detection limits of probes were up to 8.24 × 10−8 M for Cu2+ ion, which were much lower than drinking water permission concentrations by the United States Environmental Protection Agency. Sequentially, the L1-Cu2+, L2-Cu2+ and L3-Cu2+ complexes detected citrate anion (CA) through "turn on" response. The probes, were also found to be reversible and recyclable toward Cu2+ ion and CA controlled "On–Off–On" fluorescent switch and acted as molecular logic gates. Furthermore, the in vivo sensitivity experiments of Cu2+ ion and CA were demonstrated through fluorescence imaging in living cells. Graphical abstract In this study, we reported three novel probes L1, L2 and L3 for highly selectively and sensitivity detected Cu2+ ion through "turn off" response in DMF/H 2 O solution (v/v = 1/1, 0.01 M, Tris-HCl buffer, pH 7.30). Sequentially, the L1-Cu2+, L2-Cu2+ and L3-Cu2+ complexes detected citrate anion through "turn on" response, which could be applying as molecular logic gate. Furthermore, the in vivo sensitivity experiments of Cu2+ ion and citrate anion were demonstrated through fluorescence imaging in living cells. Image 1 Highlights • Three novel fluorescent probes L1, L2 and L3 exhibited excellent selectivity and sensitivity for the sequential detection of Cu2+ ion and citrate anions (CA). • The binding modes of probes L1, L2 and L3 with Cu2+ ion had been well demonstrated by UV–vis, fluorescence, IR and DFT calculation. • The detection limit of probe L3 for Cu2+ ion was 8.24 × 10−8 M which lower than the U.S. EPA limits and WHO of Cu2+ ion detection in drinking water. • The probes could act as INHIBIT logic gates and applied for Cu2+ ion and CA fluorescence imaging in living cells. [ABSTRACT FROM AUTHOR]