Fluorescent sensing platform for low-cost detection of Cu$^{\mathbf{2+}}$ by coumarin derivative: DFT calculation and practical application in herbal and black tea samples

Authors: TAHİR SAVRAN, ABDURRAHMAN KARAGÖZ, ŞÜKRİYE NİHAN KARUK ELMAS, DUYGU AYDIN, FURKAN ÖZEN, KENAN KORAN, FATMA NUR ARSLAN, AHMET ORHAN GÖRGÜLÜ, İBRAHİM YILMAZ

Abstract: A fluorogenic probe based on a coumarin-derivative for Cu$^{2+}$ sensing in CH$_{3}$CN/H$_{2}$O media (v/v, 95/5, 5.0 \textmu M) was developed and applied in real samples. 3-(4-chlorophenyl)-6,7-dihydroxy-coumarin (MCPC) probe was obtained by synthetic methodologies and identified by spectral techniques. The probe MCPC showed remarkable changes with a ``turn-off'' fluorogenic sensing approach for the monitoring of Cu$^{2+}$ at 456 nm under an excitation wavelength of 366 nm. The response time of the probe MCPC was founded as only 1 min. The detection limit of the probe MCPC was recorded to be 1.47 nM. The binding constant and possible stoichiometric ratio (1:1) values were determined by Benesi-Hildebrand and Job's plot systems, respectively. The mechanism of the probe MCPC with Cu$^{2+}$ was further confirmed by ESI-MS and FT-IR analyses, as well as supported by theoretical calculations. Furthermore, the probe MCPC was successfully employed for the practical applications to sense Cu$^{2+}$ in different herbal and black tea samples. The proposed sensing method was also verified by ICP-OES method.

Keywords: Coumarin, fluorescent sensor, copper, DFT, tea samples

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