Synthesis and crystal structure of ULM-16, a new open-framework fluorinated gallium phosphate with 16-ring channels: Ga4(PO4)4F2·1.5NC6H14· 0.5H2O·0.5H3O

Abstract

The synthesis and single-crystal X-ray structure of ULM-16, a new fluorinated gallophosphate Ga₄(PO₄)₄F₂·1.5NC₆H₁₄·0.5H₂O·0.5H₃O is described. This material is prepared hydrothermally at 180 °C using cyclohexylamine as structuring agent. It crystallizes in the orthorhombic space group Pbcn(no. 60) with a= 27.329(4), b= 17.377(2), c= 10.2124(5)Å, V= 4849.6(9)ų and Z= 8, with R= 0.0477 for 3006 observed reflections [I > 2σ(I)]. The structure is built up from vertex-linked GaO₄ and PO₄ tetrahedra, GaO₄F trigonal bipyramids and GaO₄F₂ octahedra forming hexameric and tetrameric units. The three-dimensional framework consists of one-dimensional circular tunnels delimited by sixteen polyhedra and is stable up to 800 °C.