Synthesis and Crystal Structure of a Layered Silicate HUS-1 with a Halved Soda lite-Cage Topology
Synthesis and Crystal Structure of a Layered Silicate HUS-1 with a Halved Soda lite-Cage Topology
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DOI：
10.1021/ic1020065
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发表时间：
2011-03-21
影响因子：
4.6
通讯作者：
Izumi, Fujio
中科院分区：
文献类型：
--
作者：
Ikeda, Takuji;Oumi, Yasunori;Izumi, Fujio
以FAU型和BEA型分子筛为原料，采用水热法合成了新型层状硅酸盐HUS-1。通过X射线粉末衍射法和固态魔角旋转（MAS）NMR光谱的结构分析显示，HUS-1具有层状结构，其包含沿沿着堆叠方向的每个晶胞的硅酸盐层。它的骨架拓扑结构类似于SOD型沸石，由一个半方钠石笼组成，其中包括四元和六元Si环。通过Rietveld方法进行的结构精修表明，用作结构导向剂（SDA）的四甲基铵（TMA）离子被引入到夹层中。TMA分子的四个甲基在硅酸盐层中有序地位于半球形笼中，这表明分子运动受到限制。层间距估计为约0.15 nm，与其它层状硅酸盐（例如，β-HLS或RUB-15）。通过H-1 MAS NMR光谱和最大熵法获得的电子密度分布，清楚地揭示了相邻末端O原子之间氢键的存在。
A new layered silicate, HUS-1, was synthesized by hydrothermal synthesis using decomposed FAU- and *BEA-type zeolites as nanosized silica parts. Structural analyses by X-ray powder diffractometry and solid-state magic-angle-spinning (MAS) NMR spectroscopy revealed that HUS-1 has a layered structure containing a silicate layer per unit cell along a stacking direction. Its framework topology is similar to that of SOD-type zeolites and consists of a halved sodalite cage, which includes four- and six-membered Si rings. Structure refinement by the Rietveld method showed that tetramethylammonium (TMA) ions used as a structure-directing agent (SDA) were incorporated into the interlayer. The four methyl groups of the TMA molecule were located orderly in a hemispherical cage in the silicate layer, which suggests restraint of molecular motion. The interlayer distance is estimated at about 0.15 nm, which is unusually short in comparison with that in other layered silicates (e.g., beta-HLS or RUB-15) with similar framework topologies. The presence of hydrogen bonding between adjacent terminal O atoms was clearly revealed by the H-1 MAS NMR spectroscopy and by electron-density distribution obtained by the maximum entropy method.