Reversible fluorescent detection for sulfide with quinoline-ligated copper complexes and its application in living cells

•Reversible fluorescent detection for sulfide can be realized successfully.•The probe exhibits highly sensitivity and selectivity toward the sulfide.•Fluorescence imaging of cells for sulfide in vivo was carried out successfully.

To realized highly selective detection for sulfide anion, a simple and hydrophilic fluorescent chemosensor, sodium 2-(2-(1H-benzo[d]imidazol-2-yl)quinolin-8-yloxy)acetate (HL) based on quinoline derivative was designed and synthesized. Once combined with Cu2+ in aqueous solution, the forming quinoline-ligated copper complex displayed a rapid response with high selective and sensitive detection for sulfide anion. The fluorescent signal transduction occurs via formation-separation of complex (CuL) and CuS, which achieve reversible “ON–OFF–ON” fluorescence change, and the complex (CuL) through the combination of HL and Cu2+ was further confirmed by crystal structure. The detection limits of complex (CuL) to sulfide anion was estimated to be 1.7 × 10−7 M. Furthermore, its potential utility for biological application was explored by fluorescence microscopic imaging in live cells.

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