Synthesis and sensing behavior of a new multichannel sensor based on thiazolyl ferrocene-rhodamine for Hg2+ detection

This work presented a multichannel sensor named RB-FC for Hg2+ detection, which was simply prepared by reaction of rhodamine B hydrazide with 2-amino-4-ferrocenylthiazole. Its structure was confirmed by FT-IR, NMR, MS and X-ray diffraction. The addition of Hg(2+ )destroyed the spirolactam ring, resulting in enhanced absorbance recorded by UV-visible and fluorescence spectroscopy, in addition to color change from colorless to pink observed by the naked eye. Moreover, the molecular configuration change of RB-FC caused by coordination effect of Hg2+ to the sensor influenced the the electron density in ferrocene group, therefore the electrochemical characteristic of Hg(II)-RB-FC was different from RB-FC. Importantly, the off-on mechanism, namely the opening of the rhodamine spirolactam induced by coordination of Hg2+ to O and S atoms of RB-FC with a 1:1 stoichiometric ratio, was proposed to account for fluorescence changes. The sensor of RB-FC in aqueous medium showed a low detection limit and a rapid response to Hg2+.The developed sensor can conveniently detect mercury ions with multichannel for colorimetry, fluorescence and electrochemistry.