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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >A highly hydrated α-cyclodextrin/1-undecanol inclusion complex: Crystal structure and hydrogen-bond network from high-resolution neutron diffraction at 20K
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A highly hydrated α-cyclodextrin/1-undecanol inclusion complex: Crystal structure and hydrogen-bond network from high-resolution neutron diffraction at 20K

机译：高水合度的α-环糊精/ 1-十一烷醇包合物：20K高分辨率中子衍射的晶体结构和氢键网络

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摘要

The monoclinic C2 crystal structure of an α-cyclodextrin/1-undecanol host-guest inclusion complex was solved using single-crystal neutron diffraction. Large high-quality crystals were specially produced by optimizing temperature-controlled growth conditions. The hydrate crystallizes in a channel-type structure formed by head-to-head dimer units of α-cyclodextrin molecules stacked like coins in a roll. The alkyl chain of the guest lipid is entirely embedded inside the tubular cavity delimited by the α-cyclodextrin dimer and adopts an all-trans planar zigzag conformation, while the alcohol polar head group is outside close to the α-cyclodextrin primary hydroxyl groups. The cyclodextrin dimer forms columns, which adopt a quasi-square arrangement much less compact than the quasi-hexagonal close packing already observed in the less hydrated α-cyclodextrin channel-type structures usually found with similar linear guests. The lack of compactness of this crystal form is related to the high number of interstitial water molecules. The replacement of 1-undecanol by 1-decanol does not modify the overall crystal structure of the hydrate as shown by additional X-ray diffraction investigations comparing the two host-guest assemblies. This is the first study that analyses the entire hydrogen-bonding network involved in the formation of a cyclodextrin dimer surrounded by its shell of water molecules.
机译：使用单晶中子衍射法解决了α-环糊精/ 1-十一醇主体-客体包合物的单斜C2晶体结构。通过优化温度控制的生长条件，专门生产了大型高质量晶体。水合物以通道型结构结晶，该通道型结构是由α-环糊精分子的头对头二聚体单元像硬币一样堆积在一卷中形成的。客体脂质的烷基链完全嵌入由α-环糊精二聚体界定的管状腔内，并具有全反式平面之字形构象，而醇极性头基在α-环糊精伯羟基附近。环糊精二聚体形成柱，与通常在类似线性客体中发现的水合较少的α-环糊精通道型结构中已经观察到的准六边形紧密堆积相比，其采用准正方形排列的紧凑性低。这种晶型缺乏致密性与大量的间隙水分子有关。用1-癸醇代替1-十一烷醇并不会改变水合物的整体晶体结构，如通过比较两个主客体组件的其他X射线衍射研究所示。这是第一项分析整个氢键网络的研究，该网络涉及环糊精二聚体的形成，并被其水分子壳包围。

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