Synthesis, characterization and structure determination of two isotypes of a layered aluminophosphate with a new 2D network topology

Two isotypes of a new layered aluminophosphate, further denoted MDAP-3 and MDAE-1, have been synthesized under hydrothermal conditions using N-methyl-1,3-propanediamine and N-methyl-ethylenediamine, respectively. MDAP-3, with the empirical formula Al₂(HPO₄)(PO₄)₂](C₄N₂H₁₄)(H₂O), crystallizes in the orthorhombic space group Pna2(1) (No. 33) with , , , Z=4, R₁=0.0498 and wR₂=0.1217. The second solid, MDAE-1, with the empirical formula Al₂(HPO₄)(PO₄)₂](C₃N₂H₁₂)(H₂O), crystallizes in the same space group with , , , Z=4, R₁=0.0407 and wR₂=0.0954. The two compounds possess the same layer topology. Inorganic layers contain PO₃=O, PO₃OH, AlO₄ and AlO₆ polyhedra, linked together to generate a new 4×8 net. MDAP-3 and MDAE-1 represent the first examples of two-dimensional layered aluminophosphates with the Al₂P₃O₁₂ stoichiometry, and containing AlO₆ octahedra.