Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

• Lanthanide coordination polymer of Tb-CIP/AMP was synthesized via a simple self-assembly process.
• AMP was employed as a bifunctional molecule for both fluorescence sensitization and target recognition.
• Hypersensitive detection of Hg2+ was achieved based on time-resolved spectroscopy.

Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg2+ detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb3+ from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg2+ into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg2+. As a kind of Hg2+ nanosensor, the probe exhibited excellent selectivity for Hg2+ and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg2+ in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging.

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