Carbon dots–quinoline derivative nanocomposite: facile synthesis and application as a “turn-off” fluorescent chemosensor for detection of Cu2+ ions in tap water

Abstract

In this paper, a novel quinoline derivative: 8-(pyridin-2-ylmethoxy)quinoline-2-carboxylic acid (Q) has been successfully synthesized, then it was coupled with carbon dots (CDs) to synthesize a CDs–Q nanocomposite by a simple and green method. The CDs–Q nanocomposite can act as a “turn-off” fluorescent chemosensor for detection of Cu²⁺ ions. It's a good candidate for Cu²⁺ sensing on account of its excellent properties such as its high sensitivity and selectivity, easy synthesis, excellent fluorescence stability towards temperature and pH, direct detection in aqueous solution and tap water and distinct fluorescence quenching towards Cu²⁺. We have also discussed the fluorescence quenching mechanism of CDs–Q and the possible coordination mode of CDs–Q with Cu²⁺. CDs–Q have a wide linear range (0.01–1.2 μM) and high sensitivity towards Cu²⁺ ions with a detection limit of 0.56 nM. In addition, this fluorescent chemosensor was also applied to determine Cu²⁺ in tap water with satisfying results.