Molecular Sieves Group, Instituto de Catálisis y Petroleoquímica, ICP-CSIC, C/ Marie Curie 2, 28049, . Madrid, Spain.
Berzelii Center EXSELENT on Porous Materials, Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
Chemistry. 2022 Jul 26;28(42):e202200702. doi: 10.1002/chem.202200702. Epub 2022 Jun 8.
(1S,2S)-N-methyl-pseudoephedrine (MPS) was used as organic structure-directing agent (OSDA) for the synthesis of Mg-doped nanoporous aluminophosphates. This molecule displays a particular conformational behavior, where the presence of H-bond donor and acceptor groups provide a rigid conformational space with one asymmetric conformation preferentially occurring. MPS drives the crystallization of Mg-containing AFI materials. Characterization of these materials shows that the OSDA incorporate as protonated species, arranged as head-to-tail monomers. Combination of three-dimensional electron diffraction with high-resolution synchrotron powder X-ray diffraction allowed to locate both the Mg and the organic species. Interestingly, results showed that the spatial incorporation of Mg is driven by the hydroxyl groups of the organic cation through the development of H-bonds with negatively-charged MgO tetrahedra. This work demonstrates that H-bond forming groups can be used to drive the spatial incorporation of low-valent dopants within zeolitic frameworks, a highly desired aim in order to control their catalytic activity and selectivity.
（1S，2S）-N-甲基-伪麻黄碱（MPS）被用作有机结构导向剂（OSDA）来合成镁掺杂的纳米多孔磷酸铝。该分子表现出特殊的构象行为，其中氢键供体和受体基团的存在提供了刚性的构象空间，优先发生一种不对称构象。MPS 驱动含镁 AFI 材料的结晶。对这些材料的表征表明，OSDA 以质子化形式存在，排列为头对头单体。通过与高分辨率同步加速器粉末 X 射线衍射相结合的三维电子衍射，能够定位 Mg 和有机物种。有趣的是，结果表明，Mg 的空间掺入是由有机阳离子的羟基通过与带负电荷的 MgO 四面体形成氢键来驱动的。这项工作表明，形成氢键的基团可用于在沸石骨架中驱动低价掺杂剂的空间掺入，这是一个非常理想的目标，以控制它们的催化活性和选择性。
