Zeolite-like Nanoporous Gadolinium Complexes Incorporating Alkaline Cations

In this article, we describe the synthesis and single-crystal X-ray structural studies of two new lanthanide complexes of formula [MILnIII(bta)(H2O)3]·nH2O, (M = Na (1), K (2); Ln = Gd; H4bta = 1,2,4,5-benzenetetracarboxylic acid) to check the ability of rare earth ions to lead to high-dimensional materials. The crystal structures of 1 and 2 can be described as a succession of layers made up of chains with regular alternation of pairs of Gd3+ and Na+ or K+ ions that are connected by bta4- groups. Both structures contain a nine-coordinated gadolinium(III) cation ion and fully deprotonated bta4- anion. However, the alkaline cations exhibit different coordination numbers, seven (Na+) and nine (K+). The structures accommodate crystallization and coordination water molecules, and it was observed that the water molecules have a significant influence on the coordination geometry and on the overall extended structure. These compounds may be considered as novel nanocomposites of unusual structures within the benzenetetracarboxylate frameworks.