Kiesilä Anniina, Beyeh Ngong Kodiah, Moilanen Jani O, Puttreddy Rakesh, Götz Sven, Rissanen Kari, Barran Perdita, Lützen Arne, Kalenius Elina
Department of Chemistry, Nanoscience Center, P. O. Box 35, FI-40014 University of Jyväskylä, Finland.
Org Biomol Chem. 2019 Jul 24;17(29):6980-6984. doi: 10.1039/c9ob01383k.
Pyridinearene macrocycles have previously shown unique host-guest properties in their capsular dimers including endo complexation of neutral molecules and exo complexation of anions. Here, we demonstrate for the first time the formation of hydrogen bonded hexamer of tetraisobutyl-octahydroxypyridinearene in all three states of matter - gas phase, solution and solid-state. Cationic tris(bipyridine)ruthenium(ii) template was found to stabilize the hexamer in gas phase, whereas solvent molecules do this in condensed phases. In solution, the capsular hexamer was found to be the thermodynamically favoured self-assembly product and transition from dimer to hexamer occurred in course of time. The crystal structure of hexamer revealed 24 N-HO direct intermolecular hydrogen bonds between the six pyridinearene macrocycles without any bridging solvent molecules. Hydrogen bond patterns correlate well with DFT computed structures. Thus, all structural chemistry methods (IM-MS, DOSY NMR, DFT, X-ray crystallography) support the same structure of the hexameric capsule that has a diameter of ca. 3 nm and volume of 1160 Å3.
吡啶芳烃大环化合物此前已在其胶囊状二聚体中展现出独特的主客体性质，包括对中性分子的内络合作用以及对阴离子的外络合作用。在此，我们首次证明了四异丁基 - 八羟基吡啶芳烃在物质的三种状态——气相、溶液和固态中均能形成氢键连接的六聚体。发现阳离子三（联吡啶）钌（II）模板在气相中稳定六聚体，而在凝聚相中则是溶剂分子起到稳定作用。在溶液中，胶囊状六聚体被发现是热力学上有利的自组装产物，并且随着时间的推移会发生从二聚体到六聚体的转变。六聚体的晶体结构显示，六个吡啶芳烃大环之间存在24个N-HO直接分子间氢键，且没有任何桥连溶剂分子。氢键模式与密度泛函理论（DFT）计算的结构高度相关。因此，所有结构化学方法（离子淌度质谱、扩散排序核磁共振谱、DFT、X射线晶体学）都支持具有约3纳米直径和1160 ų体积的六聚体胶囊的相同结构。
