Hydrothermal syntheses, structures and properties of five rare earth coordination polymers with (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid

Hydrothermal reactions of rare earth ions(III) with a flexible building unit (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H(2)tzda) lead to five novel coordination polymers with 1D chain and 3D network structures, namely, {[Y-2(tzda)(3)(H2O)(10)]center dot 5H(2)O}(n) (1) and [Ln(2)(tzda)(3)(H2O)(5)](n) [Ln=Er (2), Pr (3), Nd (4), Eu (5)]. Compound 1 has one-dimensional ribbon-like chain structure constructed by [Y-2(tzda)(3)] units through the syn-anti bidentate bridging mode of carboxylate groups. Compounds 2-5 possess compact three-dimensional network structures which are made up of [Ln(2)(tzda)(3)] (Ln=Er, Pr, Nd and Eu) units bridged by carboxylate groups. In these compounds, the flexible tzda(2-) ligand is versatile and displays six different coordination fashions to meet the requirement of the coordination preference of the metal center. Furthermore, the magnetic behaviors for 2-5 in the temperature range of 5.0-300 K and photoluminescent property of 5 are significantly investigated in this paper. (C) 2007 Elsevier B.V. All rights reserved.