A simple quinoline-derived fluorescent sensor for the selective and sequential detection of copper(ii) and sulfide ions and its application in living-cell imaging

摘要

A simple amide compound (QLBA), prepared from quinoline-2-carboxylic acid and 2-(1H-benzo[ d ]imidazol-2-yl)aniline, was synthesized and evaluated as an efficient fluorescence chemosensor for the selective recognition of copper ions (Cu ~(2+) ). This sensor could detect Cu ~(2+) in CH _(3) OH/HEPPES buffer in a wide pH range (4.0–10.0), with obvious fluorescence quenching. The obtained QLBA–Cu ~(2+) complex could be used as a new cascade sensor for detecting sulfide anions (S ~(2?) ). The corresponding detection limits were found to be 2.2 × 10 ~(?7) M for Cu ~(2+) and 4.6 × 10 ~(?7) M for S ~(2?) . The sensing mechanisms of QLBA toward Cu ~(2+) were systematically investigated in detail by NMR, HR-MS analysis, and density functional theory (DFT) calculations. In addition, this sensor was verified to be of low cytotoxicity and to have good imaging characteristics for the detection of Cu ~(2+) and further for the recognition of S ~(2?) in living cells, suggesting that QLBA was a useful tool for tracking Cu ~(2+) and S ~(2?) ions in vivo .