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

摘要

Inorganic-organic hybrid frameworks, namely [Ce(H_2O)_3(pdc)]_4[SiW_(12)O_(40)]·6H_2O 1, [M(H_2O)_4(pdc)]_4[SiW_(12)O_(40)]·2H_2O (M=Ce for 2a, La for 2b, Nd for 2c; H_2pdc=pyridine-2,6-dicarboxylic acid) were assembled through incorporation of Keggin-type heteropolyanion [SiW_(12)O_(40)]~(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 [SiW_(12)O_(40)]~(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 [SiW_(12)O_(40)]~(4-). Solid-state properties of compounds 1 and 2a-c such as thermal stability and photoluminescence have been further investigated.