一个具有三明治结构的包合物:8-羟基喹啉-β-环糊精包合物的晶体结构

A Novel Inclusion Complex of 8-Hydroxyquinoline Sandwiched Between Two β-Cyclodextrins

合成了8-羟基喹啉与β-环糊精的包合物,通过X射线单品衍射研究了它的晶体结构.结果显示其不对称单元包含2个β-环糊精、1个8-羟基喹啉,2个乙醇和30个水分子.其中两个β-环糊精分子通过仲羟基间氢键以头对头的方式形成二聚体,客体8-羟基喹啉被包合在此二聚体的中间区域,分子平面与环糊精的大环平面平行,形成了一个具有三明治夹心结构的包合物.两个环糊精空腔各包合一个乙醇分子,30个水分子分散在β-环糊精二聚体之间.研究表明,β-环糊精二聚体的三明治区域是疏水的,对于某些大小合适且具有平面构型的客体分子,如8-羟基喹啉,此三明治区域比β-环糊精空腔具有更强的包合能力,这科新颖的包合方式是乙醇与8-羟基喹啉竞争包合的结果.

A supramolecular inclusion complex was prepared between β-cyclodextrin （β-CD） and 8-hydroxyquinoline, and its crystal structure was investigated by single-crystal X-ray crystallography. The asymmetric unit consists of two β-CDs, one 8-hydroxyquinoline, two ethanol and thirty water molecules. Two β-CDs form a head-to-head dimer by means of extensive hydrogen bonding across the secondary hydroxyl groups. One 8-hydroxyquinoline molecule is sandwiched in the interface of the dimer and is parallel to the plane of β-CD macrocycle. Each β-CD of the dimer includes one ethanol molecule in its cavity. Thirty water molecules are distributed in the interstices between β-CD dimers. The results indicate that the interface of the β-CD dimer has stronger inclusion ability than the cavity of β-CD for some suitable planar molecules. The novel inclusion structure results from the competitive inclusion of 8-hydroxyquinoline and ethanol molecules.