Synthesis and spectral characterization of the phenothiazine-thiosemicarbazide probe for the optical solid-state detection of Hg 2+ and Cu 2 .

In this study, a phenothiazine-thiosemicarbazide (PTZDS) probe was synthesized and characterized. The synthesized PTZDS probe exhibited a yellow color, with a native fluorescence emission at λ _emission = 550 nm and λ _excitation = 450 nm. Over other metal ions, the probe exhibited significant selectivity and sensitivity towards Hg ²⁺ and Cu ²⁺ . The probe showed fluorescence quenching along with a minor shift in the absorbance spectra from 400 to 450 nm and 430 nm in the presence of Hg ²⁺ and Cu ²⁺ , respectively. In addition, the color of the synthesized probe remarkedly faded with the addition of Hg ²⁺ or Cu ²⁺ . Fluorescence measurements, infrared spectroscopy (IR), and density functional theory studies were employed to elucidate the binding process in the PTZDS + Cu ²⁺ and PTZDS + Hg ²⁺ sensor systems. Furthermore, photophysical investigations of the synthesized probe with Hg ²⁺ and Cu ²⁺ were performed. Finally, the probe was successfully employed as a solid-state thin layer chromatography (TLC) optical sensor for detecting Hg ²⁺ and Cu ²⁺ ions.
Competing Interests: The authors declare no competing interests.
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