Molecular dynamics of novel alpha-cyclodextrin adducts studied by C-13-NMR relaxation
Molecular dynamics of novel alpha-cyclodextrin adducts studied by C-13-NMR relaxation
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DOI：
10.1021/jp9638447
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发表时间：
1997-06-26
影响因子：
3.3
通讯作者：
Baglioni, P
中科院分区：
文献类型：
--
作者：
Ceccato, M;LoNostro, P;Baglioni, P
在聚（乙二醇）（PEG）的存在下，α-环糊精形成一种称为“分子项链”的分子加合物，属于聚轮烷类。α-环糊精与环氧氯丙烷的缩合反应形成了所谓的“分子管”（MT），它是一种具有中空疏水空腔的棒状刚性分子，可以作为离子或有机小分子的主体。MT是由PEG（3350）制得的，比以前工作中使用的链长得多。本文报道了用NMR研究其动力学性质的结果。通过碳自旋晶格弛豫技术，α-环糊精，分子项链和分子管。结果表明，分子管实际上是由α-环糊精分子凝聚成的线状线构成的，MT具有比其他化合物更快的再取向运动。紫外光谱表明，分子管在水溶液中与碘（I-3（-））形成主-客体体系。
In the presence of poly(ethylene glycol) (PEG), alpha-cyclodextrin forms a molecular adduct called ''molecular necklace'' that belongs to the class of polyrotaxanes. The condensation of alpha-cyclodextrin with epichlorohydrin results in the formation of the so-called ''molecular tube'' (MT), a rodlike rigid molecule with an empty hydrophobic cavity that can behave as a host for ions or small organic molecules, MT has been obtained from PEG(3350), considerably longer than the chain used in previous works, This paper reports an NMR investigation of the dynamic properties, via carbon spin-lattice relaxation technique, of alpha-cyclodextrin, the molecular necklace, and the molecular tube. The results show that the molecular tube is really formed by a linear thread of condensed alpha-cyclodextrin molecules and that MT possesses a faster reorientational motion than all the other compounds. UV spectroscopy shows that the molecular tube forms a host-guest system with iodine (I-3(-)) in aqueous solution.