An efficient Eu-based anion-selective chemosensor: Synthesis, sensing properties, and its use for the fabrication of fluorescent hydrogel probe

A novel Eu-complex Eu(TTA)(2)vinyl-phen has been designed and synthesized via simple reaction as an efficient fluorescent sensor for F-, CH3COO-, and H2PO4-. The anion-sensitivity of Eu-complex was evaluated using a series of anion in DMSO solution. On binding with F-, CH3COO-, or H2PO4-, fluorescence quenching of Eu-complex was easily observed, while no obvious fluorescence change could be observed in the presence of other anions. More importantly, the Eu-complex exhibited excellent selectivity and sensitivity for F- and H2PO4- in water/DMSO (5/5) solution. The titration results of UV-vis, fluorescence, and H-1 NMR spectra indicated that the fluorescence quenching can be attributed to the strong hydrogen bonding interaction between anions and imidazole group of Eu-complex. To meet application requirements for biological and environmental detection in water, we successfully prepared a Eu-based fluorescent hydrogel probe using Eu(TTA)(2)vinyl-phen and N-isopropyl acrylamide (NIPAAm) as monomers through free radical copolymerization in DMF. Emission spectra titration experiments indicated that this hydrogel probe can effectively recognize H2PO4- (detection limit 10(-5) M), but cannot recognize F- and CH3COO- in pure water. To the best of our knowledge, this is first report that Eu-based fluorescent hydrogel probe for H2PO4- detection in pure water. In addition, the emission of Eu-complex is also found to be sensitive to molecular oxygen through energy back-transfer mechanism. (c) 2012 Elsevier B.V. All rights reserved.