[Fluorescence Properties and the Detection of Nitrobenzene of Lanthanides Complex with 3,4-Thiophenedicarboxylic Acid and 1,10 Phenanthroline].

3,4-thiophenedicarboxylic acid (3,4-H2tdc) as the first ligand, 1,10-phenanthroline (phen) as the auxiliary ligand, three complexes Ln2(Htdc)2(tdc)2(phen)2(H2O)4(Ln=Eu 1, Gd 2, Tb 3) were synthesized with hydrothermal method. Single-crystal X-ray diffraction analysis reveals that complexes 1-3 were isostructural crystallize and both of complexes are binuclear molecules. In the complexes 1-3, the coordination number is nine. Each metal is bound to two 3, 4-tdc ligand, one 3,4-Htdc ligand, one phen and two water molecule. Complexes 1 and 3 display the red and green light under UV lamp, corresponding the characteristic peaks from 619 nm (5D0→7F2) and 545 nm (5D4→7F5). Complex 2 expresses a broad band at 425 nm is attributed to π*→π transition. Furthermore, under the excitation wavelength of 329 nm, the effects of different solvents on complex 1 was discussed and complex 1 could be a potential luminescent probe for detecting nitrobenzene through fluorescence quenching mechanism.

[Lanthanum Coordination Polymer Based on Benzimidazole-Dicarboxylic Acid and Phenanthroline: Crystal Structure, Fluorescence and Fluorescent Sensing for Organic Small Molecules].

Two new complexes, {[Eu3(bidC)4(phen)2(NO3)] · 2H2O}n, (1) and [Tb2(bidC)3(H2O)2] (2) (bidc=benzimidazole-dicarboxylate, phen=1, 10-phenanthrolIne) were synthesized. Complex 1 shows 1D chain structure. The asymmetric unit of 1 contains three crystallographically different Eu(3+), Eu(1)O6N2, Eu(2)O8 and Eu(3)O6N2. Complex 2 reveals 2D structure. It contains two crystallographically similar Tb(3+), Tb(1)O8 and Tb(2)O8. Complex 1 displays the emission peaks at 581, 593, 615, 654 and 702 nm, corresponding to the (5)D0-->(7)FJ (J=0-4) transitions of Eu(3+). The most intense emission at 615 nm is attributed to the (5)D-->(7)F2 transition, implies a red emission light of 1. The intensity rations I((5)D0/(7)F2)/I((5)D0/(7)F1) is about 2.5, indicating the chemical environment around Eu(3+) does not have an inversion center. Complex 2 exhibits four emission peaks at 492, 545, 584 and 622 nm, corresponding to the (5)D4-->(7)FJ (J=6-3) transitions of Tb(3+). The emission band at 545 nm corresponds to the (5)D4-->(7)F5 transition of the Tb(3+), which gives an intense green luminescence output for the solid sample. Notably, the solvent-dependent luminescence behavior of complexes 1 and 2 was discussed. They show highly selective for nitrobenzene via a fluorescence quenching mechanism. The highly selective and sensitive sensing nitrobenzene leads to its application in environmental system.