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 (Cu2+). This sensor could detect Cu2+ in CH3OH/HEPPES buffer in a wide pH range (4.0-10.0), with obvious fluorescence quenching. The obtained QLBA-Cu2+ complex could be used as a new cascade sensor for detecting sulfide anions (S2-). The corresponding detection limits were found to be 2.2 x 10(-7) M for Cu2+ and 4.6 x 10(-7) M for S2-. The sensing mechanisms of QLBA toward Cu2+ 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 Cu2+ and further for the recognition of S2- in living cells, suggesting that QLBA was a useful tool for tracking Cu2+ and S2- ions in vivo.