A MOLECULAR-ORBITAL STUDY OF CYCLODEXTRIN (CYCLOMALTO-OLIGOSACCHARIDE) INCLUSION COMPLEXES .3. DIPOLE-MOMENTS OF CYCLODEXTRINS IN VARIOUS TYPES OF INCLUSION COMPLEX
A MOLECULAR-ORBITAL STUDY OF CYCLODEXTRIN (CYCLOMALTO-OLIGOSACCHARIDE) INCLUSION COMPLEXES .3. DIPOLE-MOMENTS OF CYCLODEXTRINS IN VARIOUS TYPES OF INCLUSION COMPLEX
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DOI：
10.1016/0008-6215(90)84291-2
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发表时间：
1990-05-01
影响因子：
3.1
通讯作者：
CHUJO, R
中科院分区：
文献类型：
--
作者：
SAKURAI, M;KITAGAWA, M;CHUJO, R
通过CNDO/2 MO方法，使用各种包合络合物的X射线结构，计算了环麦芽糖-六糖、-七糖和-八糖（α CD、β CD和γ CD）以及两种类型的甲基化CD的大的偶极矩值（10-20 D）。偶极矩的相对强度为α CD <β CD <γ CD和TM-α CD <α CD。这些属性解释的部分偶极矩归因于每个葡萄糖残基的整合方面，是一个典型的例子，所谓的“大环效应”。每个CD的偶极矩从仲羟基侧指向伯羟基侧。在α CD与某些芳香客体分子的包合配合物中，客体-偶极矩与主体的偶极矩反平行。CD的偶极矩强烈地影响极性客体分子的取向，并且客体分子的结合使CD变形并引起其偶极矩的大的变化。CD的总电场在腔体内显著表达。
Large values (10-20 D) of the dipole moments were calculated for cyclomalto-hexaose, -heptaose, and -octaose (.alpha.CD, .beta.CD, and .gamma.CD) and also two types of methylated CD by means of the CNDO/2 MO method, using the X-ray structures of various inclusion complexes. The relative strengths of the dipole moments were .alpha.CD < .beta.CD < .gamma.CD and TM-.alpha.CD < .alpha.CD. These properties are explained in terms of integration of the partial dipole moment attributed to each glucosyl residue and are a typical example of the so-called "macrocyclic effects". The dipole moment of each CD was directed from the secondary to the primary hydroxyl side. In the inclusion complexes of .alpha.CD with some aromatic guest molecules, the guest-dipole moment is antiparallel to that of the host. The dipole moment of the CD strongly influences the orientation of polar guest molecules, and binding of guest molecules distorts the CD and causes large variations in its dipole moment. The overall electrical field of CDs is expressed significantly within the cavity.