Syntheses, structures and properties of 3D inorganic-organic hybrid frameworks constructed from lanthanide polymer and Keggin-type tungstosilicate

Inorganic-organic hybrid frameworks, namely [Ce(H2O)(3)(Pdc)](4)[SiW12O40]center dot 6H(2)O 1, [M(H2O)(4)(pdc)](4) [SiW12O40]center dot 2H(2)O (M=Ce for 2a, La for 2b, Nd for 2c; H(2)pdc=pyridine-2,6-dicarboxylic acid) were assembled through incorporation of Keggin-type heteropolyanion [SiW12O40](4-) within the voids of lanthanides-pdc network as pillars or guests under hydrothermal condition. Single-crystal X-ray analyses of these crystals reveal that compound 1 presents 3D pillar-layered framework with the [SiW12O40](4-) anions located on the square voids of the two-dimensional Ce-pdc bilayer. Compounds 2a-c are isostructural and constructed from 3D Ln-pdc-based metal-organic framework (MOF) incorporating noncoordinating guests Keggin structure [SiW12O40](4-). Solid-state properties of compounds 1 and 2a-c such as thermal stability and photoluminescence have been further investigated. (C) 2010 Elsevier Inc. All rights reserved.