The synthesis, structural elucidation and fluorescent sensitization detection to Hg2+ based on two lanthanide-organic complexes

Two three dimensional (3D) lanthanide polymers namely, { [Tb-2(bpda)(3)(H2O)(3)]center dot H2O}(n) (1) and {[Dy-2(bpda)(3)(H2O)(3)]center dot H2O}(n)(2) have been synthesized with 2,2'-bipyridine-4,4'-dicarboxylic acid (H(2)bpda). Both 1 and 2 were characterized systematically by elemental analysis, infrared spectroscopy and thermogravimetric analysis. Single-crystal X-ray diffraction analysis shows that these two complexes are isostructural with 3D supermolecular structure. Complexes 1 and 2 exhibit characteristic luminescence on account of "antenna effect" of effective energy transfer from the ligands to the central Ln(III) ions. 1 reveals good water-stability and high detection sensitivity for Hg2+ in aqueous solution with the detection limit of 7.2 nM. In the meanwhile, the mechanism of fluorescence sensitization has also been analyzed.