Utilization of Cyclopentylamine as Structure-Directing Agent for the Formation of Fluorinated Gallium Phosphates Exhibiting Extra-Large-Pore Open Frameworks with 16-ring (ULM-16) and 18-ring Channels (MIL-46)

Two fluorinated gallium phosphates, Ga4(PO4)4F1.33(OH)0.67·1.5NC5H12·0.5H3O·0.5H2O (ULM-16) and Ga9(PO4)8F7.3(OH)0.2·4NC5H12·0.5H3O·3.5H2O (MIL-46), have been hydrothermally synthesized by varying the fluorine amount in the presence of cyclopentylamine as structure-directing agent (at 180 °C for 3 days). Their structures were determined by means of single-crystal X-ray diffraction. The first compound (obtained with low fluorine concentration) is isostructural to the gallium phosphate ULM-16 previously prepared with cyclohexylamine. Its three-dimensional framework is built up from the connection by corner sharing of the hexameric units Ga3(PO4)3F2 together with the tetramer Ga2(PO4)2 and consists of channels bound by 16 polyhedra inserting the protonated cyclopentylamine. The second phase (prepared with high fluorine concentration) exhibits a new three-dimensional topology based on the condensation by corner sharing of the identical hexameric building block Ga3(PO4)3F2 with a pentameric species Ga3(PO4)2F4...