61 Hydrothermal Synthesis, Structures and Optical Properties of Lanthanum and Ytterbium Stilbendicarboxylic Acids

Wednesday, November 4, 2009
Ballroom A+B (Camino Real Hotel)
Paola Gil-Mateo , Department of Chemistry, University of Houston, Houston, TX
Allan Jacobson , Department of Chemistry, University of Houston, Houston, TX
Four stilbenedicarboxylic acids La4(SDC)6(H2O)8 (1), (LaX)4(SDC)6(H2O)8 (X=Ce (2), Eu (3), 5%), Y3(SDC)3.5(OH)2(H2O)2 (4), (SDC = 4,4'-stilbenedicarboxylic acid) were synthesized by hydrothermal reactions and their structures determined from single crystal X-ray diffraction, or by powder diffraction and Rietveld refinement. Compounds 1, 2 and 3 crystallize in space group P21/n, with lattice parameters a = 19.816(9) , b = 5.456(3) , c = 19.901(2) , β = 108.59 (1). Compound 4 crystallizes in space group P2/m with lattice parameters a= 17.859(5) , b=10.959(1) , c=13.926(8) , = 117.40(5) o. Compounds 2 and 3 are isostructural with 1. The structure of 1 contain a lanthanum atom coordinated to 2 molecules of water and 4 SDC units. LaO8 polyhedra are cross-linked by 2 SDC ligands forming infinite layers perpendicular to the layer stacking direction. Lanthanum oxide hydrate infinite layers are linked by 2 SDC ligands. The fluorescence properties of solid samples were analyzed. Compounds 1 and 4 show structured excitation and emission bands similar to the SDC ligand in the solid state. Compounds 2 and 3 exhibit a red shift at the excitation wavelength with respect the SDC ligand.
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