Synthesis and structural characterization of Zn-containing DAF-1

A study exploring the use of ionic liquid reactions based on imidazolium halides in molecular sieve synthesis has produced a novel zincoaluminophosphate material with an open DFO-type framework structure. This framework structure had only been observed previously in the magnesioaluminophosphate system (Mg-DAF-1) where decamethonium was used as the structure directing agent. The new Zn-DAF-1 material has been characterized using chemical and thermogravimetric analysis and C-13, F-19, Al-27 and P-31 MAS NMR techniques. Structure analysis (P6/mcc, a = 22.2244(1) angstrom, c = 42.3293(3) angstrom) using synchrotron powder diffraction data not only confirmed the framework structure, but also revealed the locations of the Al, P and Zn atoms in the framework, the N, N'-di-isopropyl-imidazolium (DIPI) ions in the pores, some fluoride ions associated with double 4-rings, and some water molecules and anions filling the remaining space. This level of structural detail had not been possible in the Mg-DAF-1 material. Four different locations for the DIPI cation were found in the two 12-ring channels and Zn was found to substitute for only one of the six crystallographically distinct Al sites to yield the approximate crystal chemical formula vertical bar(DIPI)(17)(OH, F)(11)(H2O)(23)vertical bar[Zn6Al126P132O528]-DFO.