Synthesis of quinoline functionalized fluorescent chemosensor for Cu (II), DFT studies and its application in imaging in living HEK 293 cells

[Display omitted] •A new efficient fluorescent sensor for Cu2+ ion detection is reported.•Easy method of the synthesis of the probe.•The probe exhibits a high selectivity for Cu2+ over other metal ions.•Very low Detection limit towards Cu2+ ions.•The probe can be used for tracking Cu2+ in living cells by fluorescence imaging. New fluorescent probes having quinoline moiety have been successfully synthesized for the selective Cu2+ ions detection. These sensors show a favorable selectivity towards Cu2+ ion over a broad range of other common metal ions in DMSO/H2O (2:8, v/v) HEPES buffer solution (pH = 7.4), leading to remarkable fluorescence on-off response with very low Limit of Detection (LOD) value. The robust nature of the probes was shown by the detection of Cu2+ even after repeated rounds of the experiment. Moreover, the probe can be used to detect Cu2+ in real water samples with a high precision and good accuracy. The recognition mechanism of one representative probe towards Cu2+ has been properly inspected in details by High Resolution Mass Spectrometry (HRMS) and density functional theory (DFT) calculations. Besides, fluorescence imaging studies in HEK 293 cells of that probe is also indicating that the probe is low cytotoxic and offers good photophysical properties, suggesting that this fluorescent chemosensor can be easily used to track Cu2+ ion in cells.