Hg(II)-activated emission “turn-on” chemosensors excited by up-conversion nanocrystals: Synthesis, characterization and sensing performance

• Two rhodamine-derived sensing probes for Hg(II) ions were reported.
• An up-conversion host NaYF4 lattice was chosen as the excitation host.
• Energy transfer between the host and the probe were confirmed.
• Emission “turn-on” effect, good selectivity and linear response were observed.

In this paper, two emission “turn-on” chemosensors for Hg(II) sensing were designed and synthesized. Up-conversion NaYF4 nanocrystals were prepared and used as the excitation host for both chemosensors. Spectral analysis suggested that there should be an efficient energy transfer between the host and the chemosensors, which was then confirmed by excited state lifetime analysis. Then two sensing systems using this up-conversion host and the two chemosensors were constructed, their sensing performance for Hg(II) ions was then studied. It was found that the probe emission intensity increased with increasing Hg(II) concentrations, showing an emission “turn-on” effect. Good selectivity and linear response were observed from both sensing systems.

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