Further evidence of the efficiency of the fluoride route illustrated by the hydrothermal synthesis and crystal structure of the hydroxyfluorogallophosphate Mu-20

In the present paper, the synthesis and structure determination of a new three-dimensional microporous hydroxyfluorogallophosphate, denoted Mu-20, is reported. This material was obtained by hydrothermal synthesis in the presence of ethylenediamine as organic template, using the fluoride route. Its structure was determined by single crystal X-ray diffraction. The symmetry is tetragonal, space group P4(2)/ncm, with the following unit-cell parameters: a=b=10.043(7) Angstrom and c=13.828(10) Angstrom. The three-dimensional framework of Mu-20 is completely built from chains obtained by connection of four-membered rings (4 MR) which consist of 2 Ga and 2 P atoms. In these 4 MR, the two gallium atoms are bridged by a fluorine atom. The resulting framework displays two channel systems delimited by non-planar 7 and 8 MR openings, in the a and c direction, respectively. The protonated amine is disordered inside the pores. This material was characterized by elemental and thermal analyses, XRD, SEM and C-13, F-19 and P-31 solid state NMR spectroscopy.