A fluorescent Eu(III) MOF for highly selective and sensitive sensing of picric acid

A metal-organic framework [Eu 3 L 3 (CH 3 COO) 2 (H 2 O) 2 (μ 3 -OH)]•3DMF, ( EuL , H 2 L=9 H -carbazole-2,7-dicarboxylic acid, DMF= N,N -dimethylformamide) has been synthesized under solvothermal conditions and structurally characterized. In EuL , Eu 6 O 8 clusters are four-bridged by carboxylates to form parallel-aligned Eu–O–C chains, which are further linked by the carbazole moieties of L 2− ligands to form the three-dimensional framework with rhombic channels. The EuL material with characteristic emission of Eu 3+ ion exhibits significant luminescence quenching response for picric acid (PA) and the linear Stern-Volmer plot was observed in the concentration range of 0.05–0.15 mM with K sv of 98074 M −1 . As far as we know, this K sv is among the highest values for COFs and MOFs in detection of PA. The excellent anti-interference ability and repeatability were also verified by experiments. Lastly, we investigated the luminescence quenching mechanism in the EuL sensing system.