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

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 = 550 nm and = 450 nm. Over other metal ions, the probe exhibited significant selectivity and sensitivity towards Hg and Cu. 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 and Cu, respectively. In addition, the color of the synthesized probe remarkedly faded with the addition of Hg or Cu. Fluorescence measurements, infrared spectroscopy (IR), and density functional theory studies were employed to elucidate the binding process in the PTZDS + Cu and PTZDS + Hg sensor systems. Furthermore, photophysical investigations of the synthesized probe with Hg and Cu were performed. Finally, the probe was successfully employed as a solid-state thin layer chromatography (TLC) optical sensor for detecting Hg and Cu ions.