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

Abstract
An economical and green approach to the synthesis of naphthyl derivative for detec�tion 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 detec�tion (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.