Green synthesis of naphthyl derivative as an optical sensor for the detection of l‐carnitine in food samples

An economical and green approach to the synthesis of naphthyl derivative for detection of l‐carnitine (3‐hydroxy‐4‐N‐trimethyl‐aminobutyrate) is practically important. We developed a naphthyl derivative as a probe showing ‘turn‐on’ response towards l‐carnitine selectively at pH 7.2 through ICT mechanism with a good limit of detection (LOD) of 0.126 μM. Using Job's plot for determining the binding stoichiometry, it was found that probe could form a more stable complex (1:1) with carnitine. The binding constant (K) between probe and carnitine was calculated as 8 × 107 M−1 using the Benesi–Hildebrand plot. The binding interaction of the probe with l‐carnitine was confirmed by nuclear magnetic resonance titrations, Fourier‐transform infrared spectroscopy, photo physical studies and density functional theory calculations. Meanwhile, the probe can be used to quantitatively detect carnitine in food samples. The sensor naphthyl derivative probe was synthesized by a simple method with high yield. The sensor colorimetric and fluorometric detection of l‐ Carnitine very easily in aqueous medium. The probe was easily recognized l‐ Carnitine compare than other biomolecules. The l‐ Carnitine detection of limit 126 nM in aqueous medium. In addition, the probe tested l‐ Carnitine in real sample analysis.