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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