Structure of a three-dimensional, microporous molybdenum phosphate with large cavities

The synthesis, single-crystal x-ray structural characterization, and sorption properties of a microporous molybdenum phosphate, (Me(4)N)(1.3)(H(3)O)(0.7)[Mo(4)O(8)(PO(4))(2)] . 2H(2)O (Me, methyl), are presented. The three-dimensional framework is built up from Mo(4)O(8)(4+) cubes and PO(4)(3-) tetrahedra that are connected in such a way that large, cation-filled voids are generated; these voids constitute 25% of the volume of the solid. Absorption isotherms for water show the completely reversible uptake of 4 to 5 percent by weight water into the micropores of this compound, which corresponds to 10 to 12 percent by volume.