Hydrothermal synthesis of isostructural open-framework manganese and iron borophosphates: Effect of the organic templates in determining the pore shapes

Three new isostructural organo-templated transition metal borophosphates, (C₃H₁₂N₂)[MnB₂P₃O ₁₂(OH)] (denoted MnBPO-CJ30), (C₃H₁₂N ₂)[FeB₂P₃O₁₂(OH)] (denoted FeBPO-CJ30A) and (C₄H₁₂N₂)[FeB ₂P₃O₁₂(OH)] (denoted FeBPO-CJ30B) were hydrothermally synthesized by using 1,2-diaminopropane and piperazine as the template, respectively. Single-crystal X-ray diffraction analyses reveal that the framework of MBPO-CJ30 (M = Mn, Fe) is constructed from the connection of infinite loop-branched borophosphate [B₂P₃O ₁₂(OH)^4-] chains and MO₆ octahedra, giving rise to three-dimensional (3-D) intersecting 8-, 8- and 9-ring channels along the [011], [011] and [100] directions, respectively. The negative charge of the framework is compensated by the diprotonated 1,2-diaminopropane or piperazine cations located in the 9-ring channels. These compounds are further characterized by powder X-ray diffraction, ICP, CHN, TGA, IR, and magnetic measurement. Structural analyses reveal that the organic amines that have the similar structure-directing ability but differing in size and shape have an influence on the crystal symmetry as well as the pore shapes of the 9-ring channels of these isostructures. Magnetic studies reveal that MnBPO-CJ30 exhibit antiferromagnetic behavior with weak ferromagnetic component to the magnetic interactions.