New stilbene-biscarbothioamide based colorimetric chemosensor and turn on fluorescent probe for recognition of Hg2+ cation

A new symmetrical biscarbothioamide based stilbene 2,2 '-(4,4 '-(ethene-1,2-diyl)bis(benzoyl))bis(N-phenyl-hydrazine-1-carbothioamide) (TUS) as turn on fluorescent probe and colorimetric chemosensor for detection of mercury cation was synthesized and characterized by NMR spectra, Mass spectra, IR spectra, and elemental analyses. The selectivity towards various metal cations was investigated at pH 5, TUS exhibited good colori-metric selectivity to Hg2+ ion that could be directly observed by naked-eye color change from colorless to faint yellow with short response time. Moreover, the stoichiometric ratio and the interaction of TUS fluorescent probe with Hg2+ was determined to be 1:2 complex formation, which confirmed by Job's plot, mass spectra and 1H NMR titration. The detection limit of TUS towards Hg2+ was calculated to be 0.15 mu M. The effect of the pH change in absorption and emission spectra with the absence and presence of Hg2+ cations were studied. The TUS was used for bio-imaging of HepG-2 cells and intracellular detection of Hg(2+ )by confocal microscope.

Automated summary

A new symmetrical compound TUS was synthesized and characterized as a fluorescent probe and colorimetric chemosensor for detection of mercury cation. The probe showed good selectivity and sensitivity towards Hg2+ ion, and could be directly observed by naked eye. It was also used for intracellular detection of Hg2+.