Lundén B M, Löfgren H, Pascher I
Chem Phys Lipids. 1977 Dec;20(4):263-71. doi: 10.1016/0009-3084(77)90067-6.
From data of a single crystal analysis of 12-D-hydroxyoctadecanoic acid methyl ester principles for the incorporation of hydroxyl groups into a hydrocarbon chain matrix can be deduced. In the crystalline compound infinite hydrogen bond systems are accommodated in an orthorhombic perpendicular chain arrangement. The orthorhombic perpendicular hydrocarbon subcell is expanded towards a hexagonal packing pattern, allowing more space and optimal geometry for the hydrogen bond system. The arrangement of the bond system in the orthorhombic perpendicular subcell requires that hydrogen bonded carbon chains carry alternatingly hydroxyl groups with opposite configuration. For the enantiomeric compound this requirement is met by a head to tail packing of molecules in a single layer arrangement. The corresponding racemates on the other hand pack head to head in double layers as confirmed by X-ray powder and IR studies. In monolayers both enantiomers and racemates behave identically. The hydrogen bonding of the hydroxyl groups apparently leads to the formation of lipid clusters, in which the geometric conditions for both a close packing of hydrocarbon chains and the formation of an extensive hydrogen bond system do not exist.
通过对12-D-羟基十八烷酸甲酯的单晶分析数据，可以推断出将羟基引入烃链基质的原理。在结晶化合物中，无限氢键系统以正交垂直链排列存在。正交垂直烃子晶胞向六方堆积模式扩展，为氢键系统提供了更多空间和最佳几何形状。正交垂直子晶胞中键系统的排列要求氢键连接的碳链交替带有构型相反的羟基。对于对映体化合物，这一要求通过单层排列中分子的头对尾堆积来满足。另一方面，通过X射线粉末和红外研究证实，相应的外消旋体以双层形式头对头堆积。在单层中，对映体和外消旋体的行为相同。羟基的氢键作用显然导致脂质簇的形成，在脂质簇中不存在烃链紧密堆积和形成广泛氢键系统的几何条件。
