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、结晶固体是分离、吸附、形式选择催化等领域的重要材料，也可作为仓库材料。此外，纳米多孔材料也用于太阳能蓄热装置。传统的沸石是纳米多孔材料的一个重要分支，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引起了人们的兴趣。一方面，无模板合成可以更有效地生产沸石，另一方面，利用“前体化学”合成了新的沸石框架类型，从而产生了非常有趣的、耐热的和催化活性的材料。作为前驱体，层状硅酸盐在拓扑缩合反应中转化为纳米多孔框架结构。这一概念的一般有效性已被证明适用于若干前体材料。通过使用硅酸盐单体作为连接层状前驱体的连接剂，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一种注册的排列方式相互连接。这导致晶体，纳米多孔的三维硅酸盐框架具有扩展的孔隙率和功能基团在连接位点。同样，对于不同的连接基团和不同的前驱体硅酸盐，表明了该概念的一般适用性。作为反应的技术术语，引入了“层间膨胀”。目前的建议旨在通过使用其他元素作为连接材料（如氧配位金属中心）来扩展层间的扩展。在第一次实验中，Fe作为硅酸盐前驱体被引入到层间膨胀的RUB-36中。该纳米多孔材料在500℃高温下热稳定，铁中心具有催化活性，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，铁占据了约50%的连接位点，因此，在明确的框架位点上引入了金属中心。其他金属层间膨胀反应也有很好的结果，已经在连接位点上得到了Sn、Zn、Ti、V和Eu。为了重现和优化合成，提高产品的结晶度，并证明硅在连接位点被金属中心取代，需要进行晶体结构分析，这将是项目的重点。粉末材料应通过粉末x射线衍射数据的Rietveld分析来显示体结晶度，并通过电子晶体学等单晶技术来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.