Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), c/Sor Juana Inés de la Cruz 3, 28049, Madrid, Spain.
Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas (ICP-CSIC), c/Marie Curie 2, 28049 Madrid, Spain.
Dalton Trans. 2019 Dec 28;48(48):17752-17762. doi: 10.1039/c9dt04089g. Epub 2019 Nov 25.
A short imidazolium based dication, with only three methylene units in the spacer linker, selectively directs the crystallization of zeolite HPM-12 (*UOE) as long as there is enough germanium present in the synthesis gel. The integrity of the dication is proved by dissolution of the zeolite and H and C NMR spectroscopy, where significant effects of organic dication concentration and the presence and concentration of HF need to be taken into account. For the as-made HPM-12 zeolite, a large shift of 9 ppm of one resonance in the C MAS NMR spectrum is due to the particular conformation of the dication imposed by confinement in the zeolite framework, as found by DFT calculations. The structure-directing ability of this kind of dication with varying length of the linker suggests that matching of the distance between positive charges (imidazolium moieties) and negative charges (double four rings in which fluoride resides) plays a crucial role during crystallization.
一种短的咪唑鎓双阳离子，其间隔连接体中只有三个亚甲基单元，只要在合成凝胶中有足够的锗存在，就可以选择性地指导沸石 HPM-12（*UOE）的结晶。通过溶解沸石和氢核和碳核磁共振波谱法证明了双阳离子的完整性，其中需要考虑有机双阳离子浓度以及 HF 的存在和浓度的显著影响。对于合成的 HPM-12 沸石，由于在沸石骨架中的限制，双阳离子的特殊构象导致了 C MAS NMR 光谱中一个共振的 9 ppm 的大位移，这是通过 DFT 计算发现的。这种具有不同长度间隔连接体的双阳离子的结构导向能力表明，在结晶过程中，正电荷（咪唑鎓部分）和负电荷（其中氟化物存在的双四元环）之间的距离匹配起着至关重要的作用。
