Wicher Barbara, Gdaniec Maria
Faculty of Chemistry, Adam Mickiewicz University, 60-780 Poznań, Poland.
Acta Crystallogr Sect E Struct Rep Online. 2008 May 21;64(Pt 6):o1138. doi: 10.1107/S1600536808015067.
In the title inclusion compound, 2C(24)H(40)O(5)·C(8)H(6)N(2), the unit cell contains two mol-ecules of cholic acid (3α,7α,12α-trihydr-oxy-5β-cholan-24-oic acid) and one mol-ecule of quinoxaline which implies disorder of the quinoxaline in the space group P2(1). The amphiphilic mol-ecules of cholic acid assemble, in an anti-parallel arrangement, via O-H⋯O hydrogen bonds, into typical corrugated host bilayers which are lipophilic on the outside and lipophobic on the inside. The host framework belongs to the so called α-trans subtype. The quinoxaline mol-ecules are accommodated in lipophilic channels formed between neighboring bilayers with only van der Waals inter-actions between host and guest. There is a crystallographic twofold screw axis directed along an empty channel in the host framework; however, neighboring guests in any one channel are related by a unit-cell translation along the b axis. Thus, the overall structure is a 1:1 superposition of two such channels related by the crystallographic twofold screw axis.
在标题包合物2C(24)H(40)O(5)·C(8)H(6)N(2)中，晶胞包含两个胆酸（3α,7α,12α-三羟基-5β-胆烷-24-酸）分子和一个喹喔啉分子，这意味着喹喔啉在空间群P2(1)中存在无序。胆酸的两亲性分子通过O-H⋯O氢键以反平行排列组装成典型的波纹状主体双层，其外部为亲脂性，内部为疏脂性。主体框架属于所谓的α-反式亚型。喹喔啉分子容纳在相邻双层之间形成的亲脂性通道中，主体与客体之间仅存在范德华相互作用。在主体框架中，有一个沿空通道方向的晶体学二重螺旋轴；然而，任何一个通道中的相邻客体通过沿b轴的晶胞平移相关联。因此，整体结构是由晶体学二重螺旋轴相关的两个这样的通道的1:1叠加。
