Microporous-structural rare-earth coordination polymers constructed by 2-bromoterephthalate

The two novel microporous rare-earth coordination polymers: La2(C8H3BrO4)32H2O (1) and Pr2(C8H3BrO4)32H2O (2) are yielded by the hydrothermal synthesis. Complex 1 and 2 are isomorphous. The Ln3þ ion center is located in the nine-coordinated environment, and both carboxyl groups of each ligand coordinate with the metal ion in the same coordination fashion. The ligands, whose carboxyl group chelates Ln3þ ion center in m1 or m3 fashion, alternately link Ln3þ ions to get the 1D chain, then the carboxyl group chelating Ln3þ ion center in m3 fashion bridges another two Ln3þ ion centers from the other two chains to form metal-organic layer. The layers are connected by the ligands in m4 fashion to furnish 1D channel-structures through b-axis. The microporous structure is well characterized by the nitrogen gas sorption and desorption. TGA and X-ray powder diffraction pattern reveal that the thermal stability of complexes is high and the open frameworks are retained upon removal of coordinated water molecules. q 2003 Elsevier B.V. All rights reserved.