Giant Voids in the Hydrothermally Synthesized Microporous Square Pyramidal−Tetrahedral Framework Vanadium Phosphates [HN(CH2CH2)3NH]K1.35[V5O9(PO4)2]·xH2O and Cs3[V5O9(PO4)2]·xH2O

• DOI: 10.1021/cm950249t
• Publication Date: 2002-07-26T05:30:15Z
• Authors: M. Isaque Khan; Linda M. Meyer; Robert C. Haushalter; Allan L. Schweitzer; Jon Zubieta; James L. Dye
• Keywords: Tetrahedron; Hydrothermal Synthesis

The use of a novel mixed-valence pentavanadate phosphate cluster as building block has made possible the low-temperature hydrothermal self-assembly new three-dimensional square pyramidal−tetrahedral framework vanadium phosphates [HN(CH2CH2)3NH]K1.35[V5O9(PO4)2]·xH2O (1) and Cs3[V5O9(PO4)2]·xH2O (2), from structurally simple starting materials. These materials possess some lowest densities largest cavities thus far observed in open-framework solid-state degree curvature, size, shape, charge mixed valence {V5O9(PO4)2} V(4+/5+) pentameric block, which resembles portion an arc circle, favors formation very large cavities. Phosphate 1 crystallizes space group I4̄3m with = 26.247(3) Å cubic-shaped that display 4̄3m point symmetry, each enclose nearly 50 positive charges. charges are distributed among 12 HN(CH2CH2)3NH2+, 32 K+ cations, several waters crystallization. Each cavity, could contain sphere approximately 13.0 diameter displays enormous 32-ring at its maximum diameter, communicates via six 16-ring windows to other similar supercages intervening smaller 2 is built up same pentamers those but arranged different manner Fd3̄m 32.306(4) such one pentamer lies on faces cube. structure consists two types larger ones all curved outward fashion, free along diagonal cavity 20 exhibiting 24-ring inside diagonals 7.5 Å. interconnected another topologically identical arrangement carbon atoms diamond. ion exchange sorption properties these also be presented.