Interlayer expansion of layer silicates with reactive metal centers, a new synthesis approach for nanoporous materials with silicate frameworks having distinct metals sites: Synthesis and crystal structure.

纳米多孔结晶固体是用于分离过程、吸附、形式选择性催化以及作为储库材料的重要材料。此外，纳米多孔材料也用于太阳能储热装置。沸石分子筛是一类重要的纳米多孔材料，而金属有机骨架或有机多孔聚合物网络等配位聚合物是目前研究的热点。然而，硅酸盐沸石的新合成路线吸引了新的兴趣。一方面，无模板合成允许更有效地生产沸石，另一方面，使用“前体化学”合成新的沸石骨架类型，导致非常有趣的耐热和催化活性材料。作为前体，使用层状硅酸盐，其已经在拓扑缩合反应中转化为纳米多孔框架结构。这一概念的普遍有效性已被证明为一些前体材料。通过使用硅酸盐单体作为连接剂桥接层状前体，实现了该方法的扩展。硅酸盐连接剂将相邻层的表面硅烷醇以配准排列彼此连接。这导致晶体，纳米多孔的三维硅酸盐框架与扩展的孔隙率和官能团在连接位点。同样，该概念的一般适用性已被证明用于不同的连接基团以及不同的前体硅酸盐。作为该反应的技术术语，“层间膨胀”已经被引入。当前的提议旨在通过使用其他元素作为连接剂材料如氧配位金属中心来扩展层间膨胀。在第一个实验中，Fe作为硅酸盐前体被引入层间膨胀的RUB-36中。这种新的纳米多孔材料在高达500 °C的温度下是热稳定的，Fe中心显示出催化活性，并且在反应过程中不会从硅酸盐中浸出。晶体结构分析的初步结果证明，Fe占据约10%的位置。50%的连接位点，并因此在明确定义的框架位点上引入金属中心。其他金属层间膨胀反应显示出有希望的结果，并且已经获得了连接位点上的Sn、Zn、Ti、V和Eu。为了重现和优化合成，提高产品的结晶度，并证明连接位点上的金属中心取代了Si，需要进行晶体结构分析，这应是该项目的重点。粉末材料应通过粉末X射线衍射数据的Rietveld分析进行研究，以显示整体结晶度，并通过单晶技术（如电子晶体学）进行研究，以获得新材料几何细节的最详细视图。

Nanoporous, crystalline solids are important materials for applications in separation processes, adsorption, form selective catalysis and also as depot materials. In addition, nanoporous materials are also used in solar heat storage devices. The classical zeolites are an important sub-group of nanoporous materials, however, coordination polymers such as metal organic frameworks or organic porous polymer networks are in the focus of interest currently. However, new synthesis routes for silicate zeolites have attracted new interest. On the one hand, template free synthesis has allowed to produce zeolites more efficiently, on the other hand, new zeolite framework types were synthesized using 'precursor chemistry', leading to very interesting, thermally resistant and catalytically active materials. As precursors, layered silicates were used which have been transformed in a topotactic condensation reaction into nanoporous framework structures. The general validity of the concept has been shown for a number of precursor materials.An extension of the approach was achieved by using silicate monomers as linkers bridging the layered precursors. The silicate linker connected surface silanols of neighbouring layers with each other in a registered arrangement. This lead to crystalline, nanoporous 3-dimensional silicates frameworks with extended porosity and functional groups at the linker site. Again, the general applicability of the concept has been shown for different linker groups and also for different precursor silicates. As technical term for the reaction "interlayer expansion" has been introduced.The current proposal is aimed at an extension of the interlayer expansion by using other elements as linker materials such as oxygen coordinated metal centers. In a first experiment, Fe has been introduced in interlayer expanded RUB-36 as silicate precursor. The new nanoporous material is thermally stable up to 500 °C, the Fe-center shows catalytic activity and does not leach out of the silicate during reaction. Preliminary results from crystal structure analysis proofed that Fe occupies ca. 50% of the linker sites and, thus, the introduction of metal centers on well defined framework sites. Other metal interlayer expansion reaction show promising results and Sn, Zn, Ti, V, and Eu on linker sites have already been obtained. In order to reproduce and optimize the synthesis, to improve crystallinity of the products, and to proof the substitution of Si by metal centers on the linker site, crystal structure analyses are required which shall be in the focus of the project. The powder materials shall be studied by Rietveld analysis of powder X-ray diffraction data to show the bulk crystallinity, and by single crystal techniques such as electron crystallography in order to obtain a most detailed view on the geometrical details of the new materials.