Cu(II) detection by a fluorometric probe based on thiazoline-amidoquinoline derivative and its application to water and food samples.

• Published in: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• Main Authors: Paisuwan, Waroton, Srithadindang, Kavisara, Kodama, Takuya, Sukwattanasinitt, Mongkol, Tobisu, Mamoru, Ajavakom, Anawat
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science 2024
• Subjects: A paper-based strip; Amidoquinoline; Cu(2+) complex; Cu(2+) detection; Fluorescence quenching; Thiazoline; Arctic
• Online Access: https://doi.org/10.1016/j.saa.2024.124706; https://pubmed.ncbi.nlm.nih.gov/38972095

Two novel fluorescent probes for Cu2+ detection have been developed based on thiazoline-quinoline conjugates bearing a 4-ethynyl-N,N-dimethylaniline unit (QT1 and QT2). QT2 exhibits instantaneous fluorescence quenching of Cu2+ with an emissive change from bright orange to arctic blue under UV light irradiation (365 nm). The plots of I0/I against Cu2+ concentrations show a good linear relationship that ranges from 0 to 50 µM with a coefficient of determination (R2) = 0.9906 and a limit of detection (LOD) of 76 nM, which is considered low (4.84 ppb). A 1:1 complexation between QT2 and Cu2+ was confirmed by UV-Vis titration, ESI-MS, and SC-XRD. The QT2·Cu2+ complex was dissociated by the addition of EDTA. The fluorescence quenching mechanism involves the ligand-to-metal charge transfer (LMCT) of a paramagnetic Cu2+ complex. The QT2 probe on a paper-based strip was used to determine the amount of Cu2+ in water and food samples (shiitake mushrooms and oysters).