Fluoride Ion Entrapment in Octasilsesquioxane Cages as Models for Ion Entrapment in Zeolites. Further Examples, X-ray Crystal Structure Studies, and Investigations into How and Why They May Be Formed

Two fluoride-encapsulated octasilsesquioxane cage compounds have been prepared using
the TBAF route as important molecular models for studying ion entrapment in siliceous
zeolites. Analyses by X-ray crystal structure and solution 19F/29Si NMR spectroscopy reveal
very similar environments for the encapsulated fluoride ion perfectly centered within each
cage with evidence of weak silicon−fluoride ion interactions. By comparing our NMR and
X-ray data with those of nonencapsulated cage analogues from the literature, we observe
the effect the fluoride ion has on the geometry of the cage and use the findings of related
studies in the literature to suggest reasons fluoride ion may be becoming entrapped in the
silsesquioxane core.

本研究通过四丁基氟化铵（TBAF）路线制备了两种氟离子封装型八硅倍半氧烷笼状化合物，作为研究硅质沸石内离子截留行为的重要分子模型。经X射线晶体结构与溶液态19F/29Si核磁共振波谱分析发现，两个笼体中的包封氟离子均完美位于笼体中心，所处化学环境高度相似，且存在弱硅-氟离子相互作用。将本研究的核磁共振与X射线数据与文献报道的非包封笼状类似物数据进行对比后，我们明确了氟离子对笼体几何结构的影响；同时结合文献中相关研究的结论，探讨了氟离子能够被截留于倍半硅氧烷笼核中的潜在原因。