Partial substitution of the amine template by alkali metals (Rb, Cs) in the open-framework gallium phosphates ULM-3 and TREN-GaPO

Abstract

The fluorinated gallium phosphates ULM-3 and TREN-GaPO were hydrothermally synthesized in the presence of organic templates (1,3-diaminopropane, dap, or tris(2-aminoethyl)amine, tren) and alkali metals (Rb, Cs). The solids were structurally characterized by single-crystal X-ray diffraction, and the structure examination indicates that the amine molecules are partially replaced by alkali cations. In ULM-3 (M δ [Ga 3(PO 4) 3(F,OH) 2], (1− δ/2)N 2C 3H 12, (1− δ/2)H 2O; M=Rb, Cs), the alkali metals are located within the 10-ring channels and partially occupy the positions of water and amine molecules ( δ≈0.07 for Rb and δ≈0.18 for Cs). In TREN-GaPO (M 0.5[Ga 3(PO 4) 3(F,OH) 2], 0.5N 4C 6H 21, H 2O; M=Rb, Cs), the alkali cations reside in the 8-ring channels, whereas the tren molecule is trapped within the 12-ring channels. The positions of rubidium and cesium atoms are compared with those of pyridine previously reported for TREN-GaPO.