In-situ synthesis of carbon dots-embedded europium metal-organic frameworks for ratiometric fluorescence detection of Hg in aqueous environment.

A novel dual-emission ratiometric fluorescent sensor (CDs@Eu-MOFs) has been synthesized successfully by encapsulating water-soluble fluorescent CDs into the chambers of Eu-MOFs via a simple one-pot hydrothermal method, which can be used for the detection of Hg in environmental water samples. The synthesized CDs@Eu-MOFs inherited simultaneously the excellent luminescence performance of Eu and CDs and exhibited good structural and fluorescence stability in aqueous solution. The presence of Hg changed the fluorescence intensity of CDs, while the fluorescence intensity of Eu-MOFs hardly changed, which could be used as the recognition part and the reference part respectively to construct the ratiometric fluorescence sensor. The obtained Hg fluorescent probe showed a wide linear range (0-300 μM) and a low detection limit (0.12 nM). The developed method can be used as a multi-functional fluorescent sensor with high sensitivity and good selectivity for the determination of Hg in actual water samples.