New lanthanide based coordination polymers with high potential porosity

Reaction in an aqueous gel medium between a lanthanide ion and the sodium salt of the naphthalene-tetra-carboxylic acid can lead to coordination polymers. We report here the synthesis, the crystal structure and the calculated porosity of the first two new coordination polymers, namely Gd[(C10H4)(COO)(3)(COOH)](H2O)(4)center dot 9H(2)O and Er-4[(C10H4)(COO)(4)](3)(H2O)(10)center dot 12H(2)O. The first compound crystallizes in the triclinic system, space group P (1) over bar (no. 2) with a=6.4456(1)angstrom, b= 12.0131(3)angstrom, c= 16.4256(4)angstrom, alpha= 107.8706(9)degrees, beta=97.0735(9)degrees, gamma=93.4771(15)degrees and Z=2. The crystal structure can be described as wavy planes strongly connected to each other by hydrogen bonds. This pseudo 3D crystal structure presents very large rectangular channels filled by crystallization water molecules. The second compound crystallizes in the monoclinic system, space group P2(1)/c (no. 14) with a=9.8442(1)angstrom, b=29.2288(2)angstrom, c= 10.8795(1)angstrom, beta=92.1767(3)degrees and Z=4. Its crystal structure is 3D and presents some large channels with rectangular sections. These channels are full of crystallization water molecules. In both cases, the crystallization water molecules have been formally removed and the porosity has been calculated using Connolly's algorithm. Both present a rather high potential porosity. (C) 2007 Elsevier B.V. All rights reserved.