Synthesis and Characterization of the New Hydroxygallophosphate Mu-18 with a Framework Topology Closely Related to That of the Hydroxyaluminophosphate AlPO4-EN3

A new three-dimensional microporous gallophosphate, named Mu-18, was obtained by hydrothermal synthesis in the presence of 1-methylpiperazine as an organic template. Its structure was determined by single-crystal X-ray diffraction. The symmetry is orthorhombic, space group Aba2 (No. 41), with a = 18.035(18) Å, b = 10.513(11) Å, and c = 14.293(11) Å. The framework, closely related to that of the aluminophosphate AlPO4-EN3, displays a one-dimensional channel system delimited by eight-membered ring openings. This new hydroxygallophosphate was characterized by XRD, SEM, elemental and thermal analyses, and 13C and 31P solid-state NMR spectroscopy.