Two novel colorimetric and fluorescent probes based on [5]helicene-rhodamine (1 and 2) were designed and synthesized. 1 and 2 exhibited Hg2+ selective detection through fluorescence resonance energy transfer (FRET) from [5]helicene donor to rhodamine acceptor. 1 and 2 also provided excellent sensitivity and selectivity OFF-ON fluorescence enhancement toward Hg2+ over other common interference metal ions in aqueous-organic medium with the detection limit of 2.3 and 0.2 ppb, respectively. The Hg2+ detection limit of 2 was lower than the recommended value for the U.S. EPA (2 ppb). The optical property of probes were evidently large pseudo-Stokes shifts for approximately 180 nm. The stoichiometry of 1:1 between probes and Hg2+ was obtained by Job’s plot analysis. The colorimetric change from greenish-yellow to orange for probe 1 and from greenish-yellow to pink for probe 2 can be observed easily by naked eye. In addition, the probes could be applied for detection of Hg2+ in real samples such as skin lightening cream and drinking water.

FRET colorimetric fluorescence sensing system based on [5]helicene and rhodamine 6G for selective determining Hg2+ ions

256th National Meeting (2018)

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