Syntheses and characterizations of heteroatom-containing open-framework aluminophosphates

Two heteroatom-containing open-framework aluminophosphates, (C ₃H₄N₂)₂FeAl₃P ₄O₁₆ and (C₃H₄N₂) ₂CrAl₃P₄O₁₆ (denoted as MAPO-CJ50, M = Fe, Cr), have been synthesized by using imidazole as the template under solvothermal conditions. The structure of FeAPO-CJ50 is determined by single-crystal X-ray diffraction, and its analogous structure CrAPO-CJ50 is identified by powder X-ray diffraction. The 3-dimensional framework of MAPO-CJ50, constructed by MO₄N₂ octahedra, AlO₄ tetrahedra, and PO₄ tetrahedra, contains interconnecting 10- and 8-ring channels. Imidazole molecules are coordinated with framework M ³⁺ ions and interact with each other through π-π stacking interactions in the channels. These two compounds show photoluminescent properties due to ligand-to-metal charge transfer. Magnetic measurements reveal that there are antiferromagnetic interactions between M³⁺ ions in the frameworks of FeAPO-CJ50 and CrAPO-CJ50.