Lanthanide-organic cation frameworks with zeolite gismondine topology and large cavities from intersected channels templated by polyoxometalate counterions.

A family of organic-inorganic hybrid frameworks, {Ln(H(2)O)(4)(pdc)} [XMo(12)O(40)].2H(2)O (Ln = La, Ce, and Nd; X = Si and Ge; H(2)pdc = pyridine-2,6-dicarboxylate), have been prepared under hydrothermal conditions and characterized by single crystal X-ray diffraction analyses, elemental analyses, IR, and thermal gravimetric analyses. Single crystal X-ray diffraction reveals that all six compounds are isostructural, and each consists of a zeolite-like four-connected three-dimensional cationic framework {Ln(H(2)O)(4)(pdc)}(4+) and ball-shaped Keggin type XMo(12)O(40) as templates. Interesting channels exist in the cationic framework with the gismondine topology, and these channels intersect each other to form large cavities, which array in a zigzag fashion and are occupied by nanosized XMo(12)O(40) counterions. Moreover, these compounds display strong photoluminescent properties in the solid state at room temperature.