Restricted motion of guests confined in carceplexes and capsules.
Restricted motion of guests confined in carceplexes and capsules.
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DOI：
10.1021/jo991433r
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发表时间：
2000-01
期刊：
影响因子：
--
通讯作者：
R. Chapman;J. Sherman
中科院分区：
文献类型：
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作者：
R. Chapman;J. Sherman
根据核磁共振数据定性地确定了客体在Carceplex和胶囊中的取向，并通过结合(1)H核磁共振信号确定了客体的分子迁移率。两者都高度依赖于客体的大小和形状，扭转机的相互转换也是如此。1，4-硫杂环己烷的嵌入导致硫杂环己烷的构象迁移率受到很大(1.8千卡/摩尔)的限制(椅子到椅子的相互转化)。1，4-二恶烷在包埋在Carceplex 1b中和可逆包裹在胶囊3b中时的构象限制条件相似(1.6kcal/mol)。胶囊化引起的这种大小的构象限制是前所未有的，尤其是对于非共价连接的胶囊。
Guest orientation within carceplexes and capsules was determined qualitatively from NMR data, and the molecular mobility of guests was determined via coalescence of (1)H NMR signals. Both are highly dependent on guest size and shape, as is interconversion of twistomers. Incarceration of 1,4-thioxane results in a large (1.8 kcal/mol) constraint on thioxane's conformational mobility (chair-to-chair interconversion). Similar conformational constraints (1.6 kcal/mol) were determined for 1,4-dioxane both when incarcerated in carceplex 1b and when encapsulated reversibly in capsule 3b. Encapsulation-induced conformational constraints of this magnitude are unprecedented, and are particularly striking for the noncovalently linked capsules.